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FAQ | Links | DIY | Reference - Table of Contents - 1.8t

463834 Views 30 Replies 15 Participants Last post by  Vegeta Gti
The main 1.8t FAQ is great and all...but it isn't kept updated with all the new, great stuff people do. The user who created it won't respond to PM's and the mods won't edit it either. On the same note, we keep pointing all the new users at the FAQ as their first mode of defense.

I'm creating this so we can create a supplementary FAQ. I'd also like to throw in here useful links to other 1.8t related site, services, DIYs, and reference guides.

I'm not going to post a lot of actual information in this thread unless it's extremely simple. Think of this more as a table of contents to the world of 1.8t material than a reference thread.

I'll work on this over the course of the next week or so. If you'd like to add a list of links feel free to post them up. After I pull your data into the thread I'll reply back to you at which point...please delete your post. That'll help keep this clean.

Do not post questions in here!!!!!!!!!

Keep the thread clean. Informative material only.



Index thread of notable 20v engine builds

To keep the earth green, use www.earth911.com to find out where to recycle parts or dump toxic fluids.
1 - 20 of 31 Posts

-- Other good 1.8t FAQs --

Big Turbo and High Performance Thread @ Audizine
The old 1.8t FAQ
1.8t FAQ @ VWVortex
General VW Wiki
SAVwKO's stock 1.8t tuning guide
1.8t Dyno Database
* Submit your dyno's here
Elsaweb VAG Online Repair Manuals
An FAQ on the basics of going Big Turbo on the 20v platform

-- Engine Building Tips & Tricks --

Block Prep

-- Useful specialty tools --

  • Offset wrenches for removing exhaust manifold Discussion Thread

  • TDC via sparkplug hole tool


    Aeroflow AF98-2036

  • These tools are perfect for disassembling a cylinder head. Both can be found on eBay:

    Left side is valve spring compressor right side is valve stem remover/installer.
  • Schley Tool VW & Audi Timing Belt Tensioner Release Tool 67650
  • Oetiker Clamp Removal Tool

    Sargent Tools - 9256 PRT Pincer Clamp Removal Tool
  • Metalnerd 4CYL - Crank Yank 4cyl Crank Counterhold
    Part MNYANK
  • IE Block Torque Plate

    Item #: TPLATE01
  • 10MM 12 Point, 160mm length
    ARP Head Bolts
    Early 1.8t Head Bolts
    Late Model Transmission Flange (doesn't need the long length...but doesn't hurt)
  • 20mm hex tool

    To remove injector cups
    Verdict Motorsports VMS140
  • Polydrive, 160mm length

    Metalnerd Part # MN3452
    Good for OEM Head Bolts
  • Metalnerd 6 Lobe MAF Bit

    Part MN606000
  • X-Gate Super High Temp Wastegate oil/ lube
  • Excellent Engine Sealants
    Useful for things like the cam tensioner gasket

    * Elring Engine Sealing Compound: Part Number: 977 54003 040

    * Permatex Ultra Grey

    * Wurth Green Flange Sealant (slow drying)
  • Flywheel hold tool
    Flywheel hold tool

  • Metalnerd Serrated Alternator Pulley Bit SET

    Part MN3400
    Part 67600

    Metalnerd MNYANK-4CYL
  • Hylomar Universal Blue Racing Formula Gasket Dressing and Flange Sealant
    For valve cover gaskets, etc. It never dries, so it can usually be reused between installations
  • Resbond (r) Super High & Low Temp Threadlocker. Comes in 'red' or 'blue' depending on how strong a thread lock you want. Good for -300 - 2500F temps ... which means you can now put threadlocker on turbo nuts, bolts, and studs!

    Available at 034 motorsport, and McMasterCarr
  • Mail seal replacement tool. A must-have for new style main seals with the plastic lip instead of the old style spring retainer
    Seal remover, tool# Matra 3203
    Seal installer, tool# Matra T10053 (available at http://www.toolsource.com/)
    Crank oil seal installation instructions

-- Big Turbo Engine Bay Picture Threads --

-- Recommended Companies, Parts Vendors, and what they are really good at --

  • C & C Auto Parts, Long Beach, CA ** NOT PERFORMANCE FRIENDLY **
    * Fuel Injector cleaning, flow testing, remanufacturing
    * Wastegate remanufacturing
  • Ed Pink Racing Engines, CA
  • RC Performance, Huntington Beach, CA
  • Metalnerd
    * VW Tools
  • Cherry Turbo
    * Rebuild Turbos
  • So Cal Performance. 9723 Washburn rd. Downey, CA
    * Performance Parts (generic racing)
    * Methanol & Race Fuel
  • G Pop Shop
    * Rebuild Turbos
    * Re manufactured Turbos
    * New Turbos
  • Discount Cylinder Heads
    Rebuild cylinder heads for a good price
  • INA
    * Billet Parts
    * Throttle Body Spacers
    * Engine Building Services
  • http://www.bba-reman.com/ - Throttle body rebuilding service
  • 034 Motorsports
    * Billet Parts
    * OEM and OEM+ parts
    * 034 EFI Standalone Engine Management
    * In-House Tuning
  • 42 Draft Designs
    * Billet Parts
    * Gauge Solutions
  • ECS Tuning
    * OEM and OEM+ Parts
  • MJM Autohaus
    * OEM and OEM+ Parts
  • Parts4Vws.com
    * OEM and OEM+ Parts
  • PagParts
    * OEM and OEM+ Parts
    * Turbo Kits
    * Amazing VW Expertise on anything custom
  • Turbo International based in CA
    * Very good prices on KKK CHRA
  • CTS Turbo
    * OEM and OEM+ Parts
    * Turbo Kits
    * Amazing VW Expertise on anything custom
  • SiliconIntakes.com
    * Silicon bits
    * couplers
    * hose clamps
    Use coupon code link987 for 10% off
  • Boostcontroller.com
    * Silicon bits
    * couplers
    * hose clamps
  • Swaintech
    Powdercoating, Piston Coating, Performance coatings
  • Pag Parts
    Custom Fabrication, cam doctor, general performance shop, turbo kits, fmic kits
  • Witch Hunter
    Fuel Injector Cleaning and flow matching
  • Racetronix
    Cheap source for injectors
  • JRM Fabrication
    Billet 1.8t pieces
  • Rack Doctor
    Steering rack re manufacturing
  • Hillco, Garden Grove, CA
  • Fastenal
    Fasteners, fittings, etc etc etc
  • McMaster Carr
  • Grainger

-- Fixing & Diagnosing Problems --

Common Symptoms

  • My Cel is flashing as I accelerate. Vag com is showing misfires (either in a code or in real time data)
    # Your coil packs and/or sparkplugs may be going out. Check the coil pack diagnostic.
    # Your coil pack harness may have cracks
  • Boost builds slower than it used to
  • DIY Boost Leak Tester
  • My car is very jerky all of a sudden
    # If you have a MAF, it could be an intake leak
  • My car blows black/grey smoke
    # You may have a pre-cat exhaust leak that is causing you to run rich
    # You may be blowing oil past the oil seals in your turbo
  • Coolant Migration
    This is an odd issue where your coolant level sensor will leak and allow coolant to 'push' into the wire loom. This coolant then migrates along the loom and goes into areas such as your ECM connector. This is a VERY RARE issue but it's good to know it can happen. FYI.
    Coolant Migration Thread
  • My car blows blueish smoke
    # You may have a headgasket failure
  • My car is overheating
    # This is a complicated one. Check the overheating diagnostic section.
  • How to graph using Google Spreadsheets / Google Docs Link
  • My car is running rich
    # Check for exhaust leak
  • My car's idle is bouncing
    # Check for intake leaks. If there are none, check for exhaust leaks.
    # Unplug your MAF. If that fixes it, clean your MAF. Try again.

1.8t Maintenance, Diagnostics, and Procedures

See less See more
-- Big Turbo Builds --
-- Bits, Pieces, and About the Engine --

Engine Overview

Weight of 1.8t engine and parts

Why is the 20v better than the 16v, etc?

Running a 1.8t backwards
* Useful for putting a 1.8t in a rear engine car such as a Vanogan, Porsche 914, etc...

Power Limits of stock 1.8t

Cutaway view of entire engine

Another cutaway view of entire engine

This is an 058 block engine such as that found in early longitudinal 1.8t's:

Engine Specs of many VW engines

The 1.8T used a cast-iron engine block and an aluminum cylinder head with dual overhead camshafts and five valves per cylinder. The engine's actual displacement of 1,781 cc comes by way of an 81-mm bore with an 86-mm stroke. Part of this engine's inherent strength comes from its use of a die-forged steel crankshaft, split forged connecting rods and Mahle forged pistons (in some applications).

Alternator repair thread
Bosch PN# F 00M 145 225
Audi PN# 038-903-803-EX , which was replaced by 06F-903-803

Alternator bearing replacement

Alternator Swap DIY
The stock alternator is 90A. If you want to run the VR6 120A alternator you'll have to swap over the pulley from your old alternator but beyond that, it's pretty straight forward. Note: It takes a special tool to remove the pulley from the alternator. Many repair shops have this tool and will swap the pulleys for you for a small fee.

Alternator underdrive pulley
See "Pulleys"

Air Filters
See "Intakes"


Continual "clicking" sounds on sharp turns usually indicates a worn outer joint. Usually the sound is loudest on the joint opposite of the turning direction.

A "clunking" sound on deceleration or acceleration may be caused by a worn inner joint. This sympton may also indicate a problem with the transaxle.
Vibration or shudder during acceleration may indicate a problem with the inner joint or a bent shaft

The stock axles use a rpezza cv joint on the outer side an a tripod cv joint on the inside. The tripod joint is not very strong and will give you problems when used at high power levels. It also does not have a large range of motion, which in turn causes problems when you increase the angle of articulation when you lower the car.

When replacing the boot on an axle, clean the cv joint and rinse any degreaser off until there is no degreaser residue left. You don't want the degreaser breaking down the CV grease. Grease the CV joint only. Do not pack the boot with grease. It has been shown that a boot packed with grease will not help your CV joint last any longer or run any better. It will simply be more grease that can get hot, get thrown around, and beat up your CV boots more, which in turn will reduce their life and cause your next leak to happen sooner. This is experience shared by [email protected] Raxles.

Upgrading to DSS or Raxles will fix both these problems. Both use rpezza inner and outer joints. If you are going low, this requires a SHORTER axle!!! If you use a standard length axle with rpezza joints on a lowered car you will cause binding. This will cause premature failure of the axle. If you are going low, please call DSS or Raxles and specify shorter axles designed for going low. If you are using shorter axles, this means if the car goes up in the air for maintenance on a rack, the axles will be overextended. You need to do something about this to prevent full extension. I'm not sure what the solution is here, but it's just one more thing you need to think about if you're going low.

Raxles makes both a motorsports grade high end axle and a budget grade OEM style axle.

There are two basic reasons to go


Lighter, Smaller Battery in Mk4


Oil Squirters[/url]
Oil squirters vary depending on engine code. This is mostly to accommodate different pistons.
AGU, BAM, Updated Oil Squirters

Fix Broken Repair Tab On Block - rear-most bolt on engine bracket

How to break in your bottom end

Block heater (for cold weather) - Part # 175 998 533A

Deck Cooling - Cutting coolant channels in the block and head or just the block so heat move better between the block and head plus clamping force on the head gasket will be improved.

058 = AEB - 1.8T 20V Motor
077 = BCY - 4.2 V8 Toaureg Motor
06A = AGU - BIG PORT Head / Drive by cable
06A = AWP/AWW/AUQ/ - Small Port Head / Drive by Wire
06F =(2.0T F/TSI)

Discussion on 06F block - Specifically provisions for rear oil feed line port

AGU / AUQ isnt 058. Both are "06A" family. A timing belt kit for an AGU will work with an AUQ as well as AWP etc.
The blocks are the same hence the water pumps are the same.

Will a standard 11mm head bolt head fit in the hole in the AUQ (smallport) head? - Yes

Is there any length differences between the 11mm bolts and the 10mm bolts?
Yes. The 06a bolts are longer because the threads start so deep in the block.

These are Raceware studs for both 058 and 06a motors. and it is also stock headbolts for each motor as well. the AEB threads start at the deck surface.

Boost Controllers

Intro to Boost Control

This is the device that allows you to control how much boost (charge air) your turbo produces. There are a few different styles of boost control.
1) PWM boost control - A solenoid that opens and closes very quickly to regulate how much pressure the wastegate sees
2) Manual Boost Control - Ball and Spring - This doesn't allow ANY pressure to get to the wastegate before a pre-set pressure is achieved...then it opens completely which holds you at your set boost pressure
3) Manual Boost Control - Bleed Type - This restricts flow to your wastegate. This is the worst kind of boost control because it always creates boost leaks and will hurt your spool up while limiting your max boost.

Factory Boost Controller
Valve Name: N75 Boost Control Valve

Electronic Boost Controller
Aka: EBC
How to hook an Apexi AVC-R into a mk4

Manual Boost Controllers
Aka: MBC
Running a MBC on a tune written for the N75

Here's how to run a MBC in parallel with the N75. The MBC will control your maximum attainable boost if you are running a ball and spring style MBC (aka 100% open or 100% closed)

Bolts & Fasteners

This is not 1.8t specific, just some good information for everyone on types of bolts, Fasteners, and what you should know about them in terms of working on the 1.8t.

Stretch Bolts (aka Torque to Yield , aka TTY)

TTY bolts are used where a more accurate, consistent clamping force is required. Torquing bolts with a torque wrench is rather inaccurate due to many things, e.g., the wrench, the user method, the angle, the fasteners, thread cleanliness, lubrication, etc. A TTY bolt will reach its plastic deformation stage at a relatively consistent torque, regardless of the above factors, so that the final clamping force on the two surfaces will be more accurate. TTY fasteners are typically used in more critical applications, e.g., internal engine components, etc. I only replace critical fasters with ones of a higher grade (ARP, etc.), but I have no issues with replacing stuff like motor mounts with 10.9 non-TTY fasteners that are torqued properly.

Hardened vs. Non-Hardened Bolts

Cut threads vs. Rolled Threads

Tensile Strength of Bolt

Anti-Seize, Oiling/ Greasing Bolts, and Proper Torquing

Boost Gauge
See "Gauges"

Cam chain tensioner
aka VVT Solenoid
aka VVT
aka CCT

The Cam chain tensioner comes in both a VVT and non-VVT configuration.

How to replace 1.8t Cam Chain Tensioner

The VVT version will retard timing 22 degrees on startup, then advance it back and leave it there while running. This is an oil-pressure powered solenoid. The electrical part initiates the advancing and retarding movement...but the movement itself is oil pressure driven.

Cam chain tensioner gasket kit

Cam Gear and Bolt
AKA "Camshaft Gear"
Available Aftermarket Cam Gears

06A Block

  • Autotech Peg Vernier (1.5 deg increments)
    * Hard Anodized 6061-T6 Aluminum gear
    * Alloy steel pin, hub, and cover plate
    * Unlimited Adjustment
  • Cat Vernier
    * 7075 Aluminum
    * Outer wheel is hard anodized
    * Adjustable to +/- 10 degrees
  • Eurospec Vernier
    * I'm not sure on materials
    * I'm not sure on max adjustment range
  • Integrated Engineering Vernier
    * Hard Anodized 6061 Aluminum
    * Stainless ARP hardware
    * Adjustment to +/- 10 degrees

058 Block

  • Autotech Vernier
    * Hard anodized 6061 Aluminum Outer, 7075-T6 Aluminum inner
    * Stainless ARP hardware
    * 14 ounces
  • Eurospec Vernier
    * I'm not sure on materials
    * I'm not sure on max adjustment range
  • Integrated Engineering
    * Hard Anodized 6061 Aluminum
    * Stainless ARP hardware
    * Adjustment to +/- 10 degrees

Cam Bolt
Always replace this.

06A Block
* One time use, OEM Part # 06A 109 281 A
* Reusable ARP @ IE, Part # ARP-06A-01

058 Block
Part # N 906 257 01
* Reusable ARP @ IE, Part # ARP-058-01

Instructions for use with the ARP bolt:
Install the gear and bolt. The bolt uses a 13/16” 12 point drive. Torque as follows- 74 ft-lb + ¼ turn with 30wt motor oil, or 78 ft-lb + ¼ turn with loctite. You will need a LONG bar to get the ¼ turn... so be prepared.

Cam Friction Disc
This goes between the bolt and cam gear as an aftermarket upgrade. This reduces the chance of the cam gear keyway shearing.

IE Part # EK-FDV2

Blow Off Valve
Aka: BOV

See "Diverter Valves, Blow Off Valves, Etc"

Cam Position Sensor
aka: CPS - This is a terrible acronym because it can be confused with the Crank Position Sensor. Please don't use this acronym!!

Please see "Sensors"

aka: cams
aka: camshaft

Camshaft FAQ Thread

Catch Cans
Discussion on Pros and Cons of various catch cans

Discussion on correct way to set up a catch can

  • Overview of what they do
  • Recirculating vs. Vent to Atmosphere (VTA) vs. Exhaust Venturi Dump
  • Pictures of the gunk they collect
  • Common flow volumes from the valve cover at idle. Common flow volumes from the block at idle.
  • Common Configurations w/ parts required

Catch Can Kits w/ Notes

  • INA
  • IE
  • Saiycho Michi (sp?)
  • 034
  • 42 draft designs
See less See more
-- Bits, Pieces, and About the Engine --

Charge Pipe

Fix for common charge pipe blowing off problem

Check Valves

Discussion about oem and aftermarket check valves

The 1.8t has lots of check valves that can fail over time. They typically fail 'open' which means they stop becoming a check valve and start becoming just an open piece of tube. This essentially creates vacuum leaks that only happens under vacuums and cannot be easily found by smoke testing or pressure testing your intake. They can also crack which causes a more traditional vacuum leak which can be found by smoke/ pressure testing.

Just to reinforce this point, pressure testing is still an EXCELLENT diagnostic tool on the 1.8t.

Many of the check valves on the 1.8t must be purchased as part of entire (expensive) hose assemblies. If you have a bad check valve but you don't want to replace the entire hose assembly, you can use these generic check valves from US Plastics for a significant savings.

Note: OEM Check valves are often half white, half black. They do not always have directional arrows on them. OEM Black & White check valves flow from white to black.

64108 - 3/16" Kynar® Standard Check Valves - $1.45
64174 - 1/4" Kynar® Standard Check Valves - $1.35
64715 - 3/8" Kynar® Standard Check Valves - $1.53

aka Bearing Clearances
common to plastigauging
aka bushing clearances
aka rod clearances
aka cam clearances
aka mains clearances

Oil pressure discussion with emphasis on bearing clearances

Clutch Switch

Clutch Switch
* Sensor located in the pedal box that tells the computer when the clutch is depressed at least a certain amount.
A faulty clutch switch will cause rev hang between gears and will cause the cruise control to not function correctly (or at all)

aka - Check Engine Codes

Codes can be retrieved via a common ODB2 code reader. However, many of the diagnostics require a more powerful interface such as Ross-Tech Vag Com to diagnose or troubleshoot.

16795/P0411/001041 - Secondary Air Injection System: Incorrect Flow Detected
Possible Symptoms
* Malfunction Indicator Light (MIL) ON
Possible Causes
* Fuel Pump Relay (J17) faulty
* Hoses/Pipes to/between Components faulty/clogged
* Secondary Air Injection Pump (V101) faulty
* Secondary Air Injection Pump Relay (J299) faulty
* Secondary Air Injection Solenoid Valve (N112) faulty
Possible Solutions
* Check Fuel Pump Relay (J17)
* Check Hoses/Pipes to/between Components
* Check Secondary Air Injection Hoses/Pipes for Carbonization
* Check Secondary Air Injection Pump (V101)
* Check Secondary Air Injection Pump Relay (J299)
* Check Secondary Air Injection Solenoid Valve (N112)

Coil Packs
Diagnosing the N122 Coil Pack 'amplifier'
AEB Coil pack Driver Pinout
Coil Pack + Heat Shield FAQ
Converting to mk5/6 coil packs
INA mk5/6 coil pack adapter
IE Coil Pack Adapters
LS Coil Conversion Parts list

Coil packs requiring 'Coil driver'
(came with the AEB)
* AEB style coil pack adapter harness made by INA allows you to use newer coils and remove your coil driver

Mk4 / B5 / B6 Coil Packs

FSI/ TSI Coil Packs
RED MKV FSI Coil Packs - 06E 905 115
BLACK MKV FSI Coil Packs - 07K 905 715 F
* This is the recommended coil
BLACK MKV TSI Coil Packs - 06F 905 115 F
BLACK MKVI TSI Coil Packs - 06H 905 115

Compression Ratio
Our motor stock came with around a 9.5:1 compression ratio. This compression ratio has been shown to support plenty of boost 30-35 lbs while still controlling detonation. At those boost pressures the larger problem is the EGTs will roast your exhaust valves. That's why people who do this use high tech exhaust valves that are oversized. This compression ratio is a great mix of boost'ability plus off-boost response. A good thing to do to make this peppier is increase displacement.

Some people will bump compression to 10:1 with a hardware kit in order to make the car more potent off-boost. However, this takes careful work and software tuning to prevent detonation.

Some people drop compression to 8.5:1 or 9:1 in order to run LOTS of boost with less chance of compression. This is not recommended for most people because it makes your car sluggish when you are off boost. If you do this it is recommended to increase displacement to 2L, 2.1L, or 2.2L.

Connecting Rods

The Official "I Broke a Rod" Thread
How to - Connecting Rod Install
Rifle Drilled rods explained
Wrist pin sizes

  • IE 19mm Rods
    * Available with Rifle Drilling
  • IE 20mm Rods
    * Available with Rifle Drilling
  • Carillo
  • Pauter
  • Brute
  • OEM

The OEM coolant is 'G12'. This is a pink colored fluid that should not be mixed with green or blue coolants. If you mix the two you will end up with brown coolant and may also get precipitants (sludge) in your coolant. You do not want that.

AEB Coolant Routing

G12/G12+/G12++ is been replaced with G13 recently. G13 is backwards compatible with G12.

VOLKSWAGEN -- 1 Gallon (3.78 Liters) -- G013A8J1G
PENTOSIN -- 5 liter (1.32 US gallons) -- 8113206 (AKA PENTOFROST E)
VAICO -- 1.5 Liter -- VA-013

Diagnosing Coolant Leaks
One method is to use the proper tools to pressurize the coolant system and check for leaks
Stant Coolant Tester Brochure
* Stant Tester - Stant 12270
* Stant VW/ Porsche Adapter - Stant 12036

If you suspect a headgasket leak you can use a block tester. This will check for combustion chamber gasses in the coolant and tell you if the leak is happening at the head gasket.
Video of block tester being used. These block testers can be purchased at most auto stores.

Groggory's trick to burping the system...

Put on some tall rubber gloves and some safety glasses. We're going to be working with hot coolant here.

With the engine running, the car's nose pointed towards the sky a bit, and the coolant ball cap off, disconnect the upper radiator hose from the front of the 4y junction. Hold it open til coolant is flowing from the engine steadily. Make sure your coolant ball stays topped off during this process. Push the hose back together and replace the spring clamp.

This will ensure you have all the bubbles out.

Replacing Coolant flange on transverse engines

Video on replacing coolant flange on transverse engines

1) remove air box

2) remove coolant sensor

3) put a bunch of rags on top of your transmission. These will catch all the coolant that is gonna spill out

4) Remove hoses from flange. Use a 1/4" drive, 10mm deep well socket + universal joint + 10" 1/4" drive extension + 1/4" ratchet to remove the two screws holding the flange on.

5) wipe flange area clean with a paper towel. Use a razor blade or scraping tool to scrape any residue off the head.

6) Smear some gasket sealant on your new coolant flange o-ring. Not too much! Just a little smear to reduce the chance of leaks.

7) Reinstall flange. Go back and forth between the two nuts so you apply even sealing force on that o-ring. These are small nuts, so don't use more than around 8-10 ft*lbs torque!!!. Remove paper towels.

8) Reinstall hoses and sensor. Wipe area clean with a rag.

9) Top off coolant ball with a 50/50 mix coolant/water. Leave coolant ball lid removed. Let the car sit for ~15-20 minutes so the sealant can set a bit.

10) Start car. Keep topping off the coolant ball as the level fills up. Keep an eye on the flange to make sure it's not leaking. If it's leaking, give a little more torque on those nuts. Once the coolant stops dropping, reinstall the coolant cap.

11) Once you're happy with the install, reinstall the airbox.

12) Keep an eye on the coolant level for the next 50 or so miles of driving.

Coolant Flange

Use OEM part or use cast aluminum part by USP Motorsports - $39.99


Swirl pot for coolant ball delete
* Thread with swirl pot in use

Coolant Radiator FAQ

Aftermarket Radiators
The stock radiator works fine for most situations. However, a higher performance radiator is useful if you will be pushing your car for extended periods of time such as with track driving, auto-x, hill climbing, or similar situations that will cause your car produce high heat for extended periods. Most aftermarket radiators require some non-OEM hoses, fittings, fans, and other bits in order to fit.

* Mk4
** Mishimoto
*** Need link to thread detailing Mishimoto installation, tips, and issues
* NB
** Need some NB aftermarket radiators
* B5
** Need some B5 aftermarket radiators
* B6
** Need some B6 aftermarket radiators

If your car is overheating after you've changed your coolant and/or worked on any part of your coolant system, you may need to 'burp' your coolant system. There are numerous ways to do this and depend on your exact engine configuration. One universal tweak is to drill a small 1/8" hole or two 1/16" holes in the outer edge of your thermostat (See here for example). This allows air bubbles to work their way out of the coolant system before the thermostat has had a chance to open.

Thermo Switch (aka Fan Temp Switch)
This is a 3 way thermostatic switch that tells your Fan Control Module (aka FCM) what speed to run the fans at. When your car is not moving there is no air flowing through the radiator, thus, the water will continue to absorb heat with no ready way to get rid of it. This is where your fans come in...your fans will kick on at either low or high speed and allow your radiator to transfer the heat from the coolant to the air. Your fan temp switch dictates at what point the coolant needs the help of the fans.
When you are moving quickly the outside air will easily flow far more air than the fans ever could. In these situations your coolant temps in the radiator will plummet. However, due to your thermostat, your engine coolant temp will remain roughly the same.

The ECU adjusts advance timing depending on the Water Temperature. It retards advance timing when the water temp is too high. If water temperature is too low the ECU will 'freak out' and give you results you won't like. This wasn't the case with earlier models such as the mk3.

Our ECU have timing maps based on coolant temps. It's not going to be a fixed coolant temperature threshold that triggers correction, but rather full maps that dictates the allowable timing advance based on coolant temp vs load/calc TQ/rpm. Simply put, anything you do that lowers your coolant temp (more than marginally), and you will be hitting load cells that allows more advance to the timing curve

Marcus_Aurelius said:
In my case, since I also have the triangle plug and can't get a lower temp thermo switch, I simply hardwired pin 2 and 3 with a cabin mounted switch. Whenever it's needed, flip the switch and and the fans stay at high speed. Switch "off", and operation is normal based on the thermo switch threshold.
More details can be found on my cooling thread below (read post # 136 for ECU related timing effect in my car and # 144 for the thermo switch mod).
Cooling Thread
The generally accepted value for a 'performance' Fan Temp Switch is 87C. This '87C' switch can be found with a square connector and is from early model mk4's. The late model mk4's moved to a triangle connector. NGP racing sells an adapter to convert your late model triangle connector to an early model square fan temp switch if you want to go that way.

Square fan temp switch -> Triangle Connector Adapter

Square rounded switches:
1H0959481B: low speed 95-84 and high speed 102-92 (stock temps from a lot of cars including Golf Mk4)
1H0959481C: low speed 90-79 and high speed 97-86 (from some Seat Ibiza/Cordoba but it seems that this one is no more available for sale and that the replacement part is 1H0959481B)
701959481: low speed 87-76 and high speed 93-82 (from Transporter T4)
701959481C low speed 81-70 and high speed 87-76 (from Transporter T4)
1H0959481D: low speed 75-70 and high speed 82-77 (from some Golf Mk3)

Triangle switch:
1J0959481A: low speed 95-84 and high speed 102-91 (stock temps from some New Beetle and so mine)

Coolant System
Great reference of both stock and performance overviews of the coolant system
Billet Coolant Fittings & Coolant Flange

Coolant Temp Sensor Housing O-Ring: Part # N90316802

Coolant Temp Sensor Housing Retaining Clip: Part # _________
Only buy OEM coolant temp sensor retaining clip. Aftermarket clips are made of an inferior material that has been known to randomly break.

What coolant to use
Always fill with a mix of water and g12. Preferably, use distilled water.

Side notes and extra information if you care...

Do not use Prestone, etc. They contain phosphates and VAG does not advise us to use phosphates in our car. Phosphates + tap water can produce deposits and corrosion using water common to Europe. Supposedly, this won't happen with North American water sources.

Mixing long life and regular coolants in ANY car will cause brown gunk and/or a jellyto build up. Case in point, mixing G12 and regular prestone, etc will cause brown gunk to build up. G12 is a long life coolant while the normal 'green' coolant is a standard life coolant. Do not ever mix these!

Prestone Extended Life 5/150 Antifreeze is phosphate, Silicate, and Borate free. This is theoretically compatible with VAG cars.

Mixing long life and long life coolants should pose no problem. Prestone, Dexcool, and many other brands make long life coolants....

My advise, just stick with G12.

Crank Position Sensor/COLOR]
aka: CPS - This is a terrible acronym because it can be confused with the Cam Position Sensor. Please don't use this acronym!!

Please see "Sensors"


Also see "pistons" for related information

Crank Gear
This is the gear that presses onto the end of the crank shaft. It is made of cast steel and has a cast key that fits in the crank. This is all held together with a single high strength bolt.
The gear has four tapped holes on it to interface with the crank dampener pulley. The 2.0T motors have five tapped holes.

High RPM motors have issues with the keyway shearing on the crank gear. The common fix is to drill one or two holes through the crank gear and into the crank, then pressing high strength steel dowel pins in. This ensures the crank gear cannot spin on the crank.

The choice of four or five bolt crank dampener interfaces is because the dampener bolts have been known to come loose sometimes. Both options have been used successfully on many high power setups.

An alternative fix for this problem is the Integrated Engineering Billet Steel crank gear. It has a press fit interface machined into it and negates the need for dowel pins. This is an excellent option. As of February 2014 this is only offered in a 4-bolt interface.


Differences between 2.0TFSI, 2.0FSI, and 1.8t Cranks
Differences between 1.8t Cranks

Remember, if you change the crankshaft stroke, you need to change the piston to compensate. Do not go for shorter rods, go for a correct piston.

Common cranks for the 1.8t:
Discussion on stroker options
* 86.4mm - Stock 1.8t Crank - 1780cc @ 81mm piston
* 92.8mm - FSI Crank - 1984cc @ 82.5mm Piston, 2008cc @ 83mm piston
* 95.5mm - TDI (ALH) Crank, generally expensive - 2067cc @ 83mm piston
* 100mm - Very uncommon, typically Eurospec Crank, MSRP $1395 USD - 2164cc @ 83mm piston

2.0t FSI and 1.9 TDI ALH Cranks are both forged.

Pilot Bearing[/url]
This is a bearings on the transmission end of the crank that is used in certain applications. A manual transmission car can accept a crank regardless of its Pilot bearing status. An automatic transmission needs a pilot bearing.

Main Bearing

OEM Main cap bolts: N 901 300 01

Billet Main Caps

They provide extreme rigidity to the main bearing and crankshaft, which is a necessity for high horsepower engines. In addition, the large profile and high strength material is much stronger and stiffer than the factory main caps.

Requires machine work including line bore & hone for fitment.

  • IE Billet 4140 Tall Boy Main Caps
    For use with a girdle
  • IE Billet 4140 Standard Billet Main Caps
  • INA

Mains bolts

Crank Girdle
Necessary on only the most extreme setups. Should be used in combination with billet main caps.

Trigger Wheel

There are three counter sunk head screws that affix the trigger wheel to the crank. When you screw them to the crank it takes a bit of material out of the trigger wheel and screw. If you loosen them and then re-torque the screws the countersink now hits the crank before hit seats the trigger wheel. This will cause the trigger wheel to not be seated properly and will wobble...which will cause problems; especially at high RPM's.

As such, consider trigger wheels and trigger wheel screws one time use.

A common practice on performance builds is to tack weld the three screws to the trigger wheel. This removes any chance of them coming loose. Some people go one step further and weld the trigger wheel to the crank, but that just brings up other issues like affecting crank balance and is not recommended for most builds. Note: Tack welding the screws still means the trigger wheel and screws are one time use. This is because of the issue with the countersunk screws bottoming out on the crank.

Cylinder Heads

Discussion on Porting, Polishing, and Port Matching

Cylinder head and camshaft removal

Discussion on rebuilding a cylinder head

Head Bolts & Head Studs
Note: 06A blocks use 10mm bolts/ studs.
058 blocks use 11mm bolts/ studs.

If you are swapping around heads, blocks, etc...use the bolt/ stud that matches the block. The diameter of the stud is the critical element.

I'm not sure which nuts for the studs do this, but I hear there are clearance issues with certain stud nuts and certain heads. If anyone knows the details of this please chime in.

Head Bolts and Head Studs

  • OEM Bolts
    *Polydrive tool necessary
  • ARP Head Bolts
  • ARP Head Studs
    *Triple square tool necessary
  • Raceware Head Bolts
  • Raceware Head Studs

Head Gaskets

Increased thickness
This is a method to drop compression without buying a lower compression rod/ piston set

Brand vs. Brand
* Victor Reinz
* Elring
* OEM (some say this is special)

Head Work

Cleaning the head
You cannot remove those balls by drilling, they are very, very hard. Pulling them out is a project in of itself. Then, when you go to reassemble, you can't just tap all the holes where the balls went because some intersect too closely- so some have to be welded, some tapped, etc.

Even with the balls out, the hot tank will not get the carbon build up out of there. It has to be removed by mechanical means- and DO NOT let them "glass bead" it- you will never ever ever get it all out of there.
Decking the Head
Head tolerances for resurfacing, honing, etc

Line Bore

See 'PCV System' for deletes related to the SAI / N249 / PCV / EVAP

Convert AEB style coils to AWP style coils (ICM Delete)
Hydraulic Power Steering -> Electric Power Steering Conversion
Clean Up Engine Bay. Relocate Battery, Fuse block, Coolant Ball, EVAP, WS Washer, Power Steering
Injector Wire Tuck DIY
Vac Reservoir Relocation & SAI Inlet Hose Edit

Air Conditioner and/or Power Steering Pump Delete
New accessory belt required:
* A/C and/or P/S Delete Belt Size (transverse applications) - 35"
13/16" x 37 1/8"(20mm x 943mm) belt Gates part number is : K060365
* A/C Delete Belt Size - 44-45.5" (OEM Belt 06A 145 933 D (1120mm/44") or NAPA/UAP belt 25-060441 for 44.75" or 25-060439 for 45.5")
(above data works with BOTH OE pullies and ECS's lightened/underdriven pullies)
GAP: 6DPK1195

Increasing Displacement
* Max possible bore diameter
* Stroker Options
* Gains
* Good Turbos to match to increased displacement + their spool and power characteristics

Diverter Valves, Blow Off Valves, Etc

How to size a wastegate or blow off valve

Good comparison thread

Good discussion on the pros and cons of various DV's

Diverter Valves

* Tial Alpha Q
* OEM 06A145710N
* Forge 007
* Forge 008
* APR R1
* Mad-Max Modified Evo DV

Blow Off Valves

  • Tial 50mm
  • Tial Q
http://bd8ba3c866c8cbc330ab-7b26c6f3e01bf511d4da3315c66902d6.r6.cf1.rackcdn.com/VW_Audi_Coolant_Cooling_G12_Plus_G13_Antifreeze_Purple_Pink_Pentosin_Vaico_OAT_HOAT_Hybrid_Silicates_Phosphates_Glycerin.pdf[/url] Great Article by ECS Tuning all about VW/ Audi Coolant Systems[/url]
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Dog Bone Mount
Mount used in transverse mounted engines
aka Pendulum Mount
See "Motor Mounts"

Dry Sump
INA Dry Sump Kit $2999 USD

See 'Fueling'


ECU Codes
Nefarious Motorsports said:
US Market Volkswagen

2000 Golf/Jetta: AWD
06A 906 032 CL
06A 906 032 CM (notes - auto)

2001 Golf/Jetta: AWW
06A 906 032 DL
06A 906 032 DM (notes - auto)
06A 906 032 GH (notes - auto)

2002+ Golf/Jetta: AWP
06A 906 032 HS
06A 906 032 LP
06A 906 032 NK
06A 906 032 SK
06A 906 032 RN (notes - 6spd manual)
06A 906 032 SM (notes - 6spd manual)
06A 906 032 LQ (notes - 5spd auto)
06A 906 032 NL (notes - 5spd auto)
06A 906 032 SL (notes - 5spd auto)
1997-1999 Passat: AEB
8D0 997 557 HX
8D0 997 559 BX

1999-2001 Passat: ATW
4B0 997 020 AX
4B0 997 020 X
4B0 997 020 BX (notes - auto)
4B0 997 020 CX (notes - auto)

2001 Passat: AUG/AWM
4B0 997 019 MX
4B0 906 018 DA
4B0 906 018 DN
4B0 906 018 DQ
4B0 906 018 FX
4B0 906 018 CM
1999-2000 Beetle: APH
06A 906 032 A (notes - auto)
06A 906 032 B (notes - auto)
06A 906 032 S (notes - auto)
06A 906 032 Q (notes - auto)
06A 906 032 E
06A 906 032 R
06A 906 032 C
06A 906 032 P

2001.5 vw passat
4B0 906 018 CL

2001+ Beetle: AWV
06A 906 032 FD
06A 906 032 DP
06A 906 032 GB
06A 906 032 KQ
06A 906 032 PT
06A 906 032 EM (notes - auto)
06A 906 032 DN (notes - auto)
06A 906 032 GA (notes - auto)
06A 906 032 KR (notes - auto)
06A 906 032 PR (notes - 5spd auto)
06A 906 032 PS (notes - 6spd tiptronic)

2002 Beetle Turbo S: AWP
1C0 906 032
06A 906 032 LS (notes - 6spd manual)
06A 906 032 QA (notes - 6spd manual)
US Market Audi

1997-1999 A4: AEB
8D0 907 559
8D0 907 557 P
8D0 997 557 HX
8D0 997 559 CX (notes - auto)

2000 A4: ATW
4B0 997 020 X
4B0 997 020 AX
4B0 997 020 BX (notes - auto)
4B0 997 020 CX (notes - auto)

2001 A4: AWM
4B0 997 019 NX
4B0 997 020 EX

2002 A4: AMB
8E0 909 518 F
8E0 909 518 G (notes - auto)
8L0 906 018 J (notes - Quattro)
8N0 997 018 BX (notes - Quattro)
8N0 997 018 DX (notes - FWD)
8N0 997 018 EX (notes - Quattro)
8N0 997 019 AX (notes - FWD)

8L0 997 018 DX
8N0 997 018 CX
8N0 997 018 FX
8N0 997 018 KX

8L0 997 018 CX
8L0 997 018 EX
8N0 906 018 AQ
8N0 906 018 BR (notes - FWD, manual)
8N0 906 018 CN (notes - auto)
8N0 906 018 CR (notes - Quattro, manual)
8N0 997 019 RX
8N0 997 019 SX
8N0 997 020 FX (notes - FWD, manual)
8N0 997 020 RX (notes - manual)
8N0 997 020 TX (notes - Quattro)
8N0 997 020 SX
8N0 997 020 QX (notes - auto)

8N0 906 018 CG
8N0 906 018 H
8N0 997 018 PX
8N0 997 018 TX

8N0 997 018 HX (notes - APP)

8N0 906 018 AP
8N0 997 019 X
8N0 997 020 EX
ME7/7.5 Software

Learn about ME7
Learn about ME7 (part2)

Wideband ECU power requirements (different from Narrowband)
Narrowband -> Wideband conversion harness
* If you have a narrowband o2 sensor, you'll want to convert to wideband so you can use the much better and more advanced wideband files made by all the major software companies. They are more powerful, smoother, and give you more options.

jwalker's wideband conversion thread
2001 Transport's wideband conversion thread

Injector FAQ
* Cross references injectors with available software

...explanation of 2-step

WOT Shifting
...explanation of WOT shifting

Tweaking ME7/7.5
Lemmiwinks Guide


* Vipec
Vipec knowledge dump for 1.8t
* Autronic
* 034 EFI
* ....


Good sources for aftermarket wiring
* Waytek
* Wiringproducts.com
* Grainger
* Amazon/ Ebay
* Sonic Electronix
* Fastenal
* McMaster-Carr

How to build a beefy replacement for the mk4 fuse box that is on top of the battery

mk4 alternator wire/ fuse problem
* read this if you 'appear' to have alternator problems

How to get an RPM signal for use in gauges, standalone systems, controllers, etc

Building a replacement for the stock fuse distribution block on top of the battery

How to build a replacement B+ wire from parts at your local auto parts store

Adding After Market Electronics Safely

Relays - Hella relays are recommended. Use only sealed relays if installing under hood.

Fuses - Always !!! add an appropriate fuse to aftermarket accessories. Set the fuse rating to about 50% more current than the device is expected to pull. Again, if installing under the hood use a sealed weatherproof fuse. Fuses are generally not very fast acting (from an electrical point of view) but good enough to prevent you from melting wire and whatnot in case of device malfunction or short circuit.

Circuit Breakers - This is an optional accessory that can be added in front of the fuse, generally connected very close to the battery. I recommend rating this to 200% of your expected current output. The reason I like to use circuit breakers is it protects you from short circuits. In case of short circuit it will trip the circuit breaker immediately before your fuses blow. When you fix the wiring fault, the circuit breaker will auto-reset.
On that note, you want a Type 1 circuit breaker. Type 1 circuit breakers will auto reset (aka cycle) when the wiring fault is removed.
Type 2 circuit breakers require you to remove power from the circuit breaker to reset it, then you can reconnect power. I think this is very inconvenient for most situations.

I generally use a combination of fuses and circuit breakers to make a robust solution.

Wire needs to be sized to the job. This is the responsibility of the wire gauge. Also, wire can handle very high currents for very short periods of time. You size the wire so that it can handle the constant load + 100% for safety margin. Also, it takes a thicker wire to handle the same load over a longer run.
eg. According to the chart below, we can use 12AWG wire to handle a 15A load for 8.5 feet. If we had a 12 foot run we would want to step up to 10AWG wire instead.

Sizing wire to the current and distance load

Insulation material must be taken into consideration. If you are mounting this under hood, you want to have a chemical and abrasion resistant insulation material that will stand up to continuous over 200F temperatures.

Core material should generally always be copper. There are very few reasons to use aluminum wire. It has higher resistance, breaks easier, but IS LIGHTER and CHEAPER. In other words, just stick with copper. It's better, lol.

When you crimp something, use the proper tool. Crimps must have the proper shape in order to have good reliability and strength. In an automotive environment, solder is not a replacement for crimps. Solder can break with vibrations. Crimps are strong mechanical connections. However, soldering crimps is a wonderful idea if you are willing to take this extra step.

Electrical Tape - Use Scotch 33 or 88 tape for all automotive electrical tape needs. They stand up to temperature without getting gooey, they stretch better, they don't harden up over time, and they have thicker backings so they are stronger than average tape. Scotch 88 has a thicker backing than Scotch 33.

Friction Tape - This is an excellent tape to wrap a wire bundle that you want to add abrasive protection to. I recommend 3M Temflex Cotton Friction Tape.

Splicing Tape - This tape is not very sticky to most things, but is stretchy as can be and bonds securely to itself. This is a great tape to seal something up with. I recommend Scotch 23.

If you want to wrap a wire bundle I recommend wrapping it with splicing tape to seal it up from the elements then wrap that in friction tape to protect it.

If you want to connect multiple bundles the old fashioned way you can learn to lace the wire. This is done using lacing tape. If you don't want to do it old school, use your electrical tape and tape them together every 8 or so inches.

Heat Shrink
This is a very professional way to seal and protect wires. This is sold in adhesive and non-adhesive styles. In 2:1 shrink and 4:1 shrink. In various colors, diameters, and thicknesses.
I recommend Raychem. That heat shrink is by far the highest quality I've worked with. 3M is a close second. Many of the other brands seem to have far less abrasion resistance than I like.

All of the electronic valves in the car that are directly controlled by the ECU are switched 'low side'. This means the ECU connects ground to that device in order to complete the circuit.

This is a three part system designed to speed up catalytic converter warm up time.

DELETE: If you delete any part of this system you will get a "SAI improper flow" code due to the computer not seeing expected output from the oxygen sensors when the SAI pump should be running. In order to remove this code you must get it 'coded out' in software. If you do not code out you will get a check engine light but will not have any performance detriments.
The most common reasons to delete is due to a failing expensive component or for hose simplification in the engine bay.
1) Combi valve on the side of the head. This is a vacuum operated valve that allows the SAI air pump to 'push' air into the exhaust ports. Vacuum is controlled by the N112. There is a small (~3/4") hole drilled across the head that connects all four exhaust ports.
If you delete the combi valve you must plug this port with a block off plate that properly seals itself against the head.
2) SAI air pump. This is an electric air pump that sucks air in from the the intake tract. Air comes after the air filter but before the MAF, so it is unmetered air. The electrical connection for this pump is driven by a relay, not directly by the computer. The relay is driven by ECU pin 66.
If you delete the SAI air pump it does not need to be resistored.
3) N112 Valve. This is a electric pneumatic valve that controls vacuum to the Combi Valve. It pulls vacuum directly from the intake manifold. The electrical connection is driven directly by the ECU on pin 9.
If you delete the N112 Valve you must replace it with a 1W 330 ohm resistor. If you do not resistor it you will get a code plus you will not get fuel trims (block 32)

N249 Valve

Discussion about removing the N249

This electric pneumatic valve controls the Diverter Valve by controlling vacuum and pressure. It also connects to the vacuum reservoir on top of the valve cover so that the diver valve can be opened when there is no vacuum present in the intake manifold.
If you delete this you must replace it with a 330ohm 1W resistor. Furthermore, you must run a vacuum line from the intake manifold to your diverter valve. If you don't resistor this you will throw a code, but your fuel trims will still adapt.

Pulled from here

Keeping the N249 smooths out coming off throttle transitions to a minor degree.

Keeping the N249 allows a bit faster respool (to a minor degree) during gear changes

Removing the N249 removes the vacuum canister and a fair amount of vacuum hoses (in addition to removing the N249).

If you remove the N249 you must resistor in order to keep fuel trims

The N249 can open only under a negative pedal position slope. No other condition will cause the N249 to open.

A negative pedal position slope does not necessarily mean the N249 will open under all circumstances.

The N249 will not protect against overboost.


All N249 Logic can be seen here in the official Bosch Logic Diagrams.

The operation of the N249 can be seen here. When the LED turns on that is the N249 activating. The boost gauge is manifold pressure.

You can see the entire system working here. This shows RPM, Throttle Body Position, Charge Pipe Pressure, Intake Manifold Pressure, MAF flow (g/s), MAF voltage (1v is zero flow)

"The N249 provides for the ECU to open the DV even if the intake manifold pressure is positve above ambient air pressure. The reason for doing this is to reduce pumping losses while at light load cruise, and other conditions, to increase fuel economy. The other reason for having the ability, is to dump excessive boost if the wastegate fails closed."



Manifold Actual Pressure Sensor
aka MAP

Shows actual pressure of charge pipe

Stock MAP is 2.5 bar absolute. Stock max range of absolute pressure is 2550 mbar / 22.5 PSI.

Stock MAP - Small orifice - PN: 038906051B
* AWW or AWP engine codes from model year 2002+

Stock MAP - Large orifice - PN: 038906051

4 bar absolute MAP: PN: 0281006059
* This is a euro spec part for cars such as the 2010 VW AMAROK 2.0 TDI. Only use this MAP sensor if your tune calls for it.
* Uses the small orifice design, same as the AWW/AWP fitment

Coil Pack Harness
How to test coil pack harness (for 4-wire coil packs)

Water Temp Sensor
aka CTS
aka Coolant Temperature Sensor

Reprogram Cluster to show REAL temperature
Another link showing how to make your gauge read the true value

The stock cluster on our cars has a big dead spot around 190F. I think anything from around 76C-106C (168F - 222F) or so will register as 88C (190F). This is to give the general public the warm fuzzies that their car is at the perfect temperature all the time. But for people who really want to know what's going on, it's akin to a sharp stick in the eye. This mod will allow you to use your in-cluster water temp sensor to show you the REAL temperature.

These original came in a black color. The later, improved model is green on top, aka Green Top.

If you were to pull the connector and have the flat side on your left - like a "D" - then the pins are numbered:

upper left - pin #1
lower left - pin #2
upper right - pin #3
lower right - pin #4

You can measure the resistance between pin 3 and 4 to get an approximate temperature.

0°C/32°F - 5000 to 6500 ohms
10°C/50°F - 3500 to 4500 ohms
20°C/68°F - 2250 to 3000 ohms
30°C/86°F - 1500 to 2000 ohms
40°C/104°F - 1000 to 1500 ohms
50°C/122°F - 700 to 1000 ohms
60°C/140°F - 525 to 650 ohms
70°C/158°F - 375 to 500 ohms
80°C/176°F - 275 to 375 ohms
90°C/194°F - 200 to 275 ohms
100°C/212°F - 150 to 225 ohms

N80 Valve
This electric pneumatic valve and charcoal filter diverts fuel vapor from the gas tank into the intake manifold. This is for emissions purposes. This is known as part of the EVAP system.
If you delete this you must replace it with a 330 ohm 1W resistor or you won't get fuel adaptations.

N75 Valve
This electric pneumatic valve controls boost pressure to the turbo wastegate.
If you delete this you must replace it with a 330 ohm 1W resistor. Furthermore, you need to use some other means to control the turbo boost pressure. If you don't resistor this you will get a code, but your fuel adaptations will work.

Crank Position Sensor
This sensor tells the engine how fast the motor is turning. In other words, you can directly correlate the pulses from this sensor into RPM's. The crank position sensor wheel has ___???____ windows per revolution.

Diagnosing the Crank Sensor:
When the crank sensor fails and causes an out-of-sync situation with the ECU the ECU cuts response to the throttle in order to prevent major engine damage. This throttle cut generally happens within a certain RPM range.

Another symptom you may also notice is that your tach (RPM) gauge hangs at a higher rev even though the car's speed is slowing. This symptom is due to the throttle being restricted by the ECU, as previously described.

Yet another symptom is the car wont start on cranking. This is because the ECU cannot determine how fast the crank is rotating due to the failed or failing crank sensor. This problem is further exacerbated by the electrical interference the starter is throwing out as you are cranking the engine which further confuses the ECU. This starting symptom is commonly incorrectly diagnosed as a failing starter throwing out extra electrical interference. However, this is rarely the case and is simply a failing or failed crank position sensor.

If the sensor is fine the problem can be mechanical. The crank position wheel is attached to the crankshaft via press fit and then secured with a screw. The screw can come loose, the screw can fall out, or the screw can shear off. Also, during old maintenance on the car the wheel can be bent by a careless mechanic which can throw off the crank balance a bit, increase the likelihood of the screw problem previously mentioned, or simply confuse the crank position sensor. This mechanical problem is typically not seen on cars turning stock RPM's (under 7500) and stock displacements. It is far more common on stroker setups or setups that turn high RPM's (over 7500). Both of these setups cause increased vibrations on the crank and in turn, put more stress on this crank position wheel. The fix for this problem if you are building a high RPM or stroker setup is to tack weld the screw in place or fully weld the entire position wheel in place.

You can get a replacement crank sensor for $20 online. It's a cheap fix for a big problem.

Fuel Pump
Controlled by the 409 relay under the dash. Battery side is pin 30. Fuel pump side is pin 87.
Pin 87 and 30 are the two 'big' pins in the relay

Relays and Major Fuses
See here for images
--Under Dash--
Above the '75x' terminal, relay 53 - Dual Tone Horn Relay
Above the '30' terminals, relay 100 - Current Supply Relay
Above the '30a' terminal, empty on a 1.8t
Above the '87f' terminal, relay 409 - Fuel Pump and o2 sensors
Next to 409 relay, empty on certain models - Wash/Wipe Relay
Above and to the left of the 53 relay, relay 173 - Not sure of function???

--Relay box on firewall, on driver's side--
Relay 428 - ECU switched power
Relay 100 - Not sure of function???

--Fuse box on top of battery--
From left to right when you open the fuse cover

1) Generator aka Alternator
2) Interior Relay Panel
3) Cooling Fans and Control Module
4) Fuel Pump or Glow Plugs
5) Secondary Air or Coolant Pre-Heating
6) Cooling Fans
7) ABS
8) ABS Pump

1. Washer nozzle heaters, glove compartment light, memory seat control module (10A).
2. Turn signal lights (10A).
3. Fog light relay, instrument panel light dimmer switch (5A).
4. License plate light (5A).
5. Comfort system, cruise control, Climatronic, A/C, heated seat control modules, automatic day/night interior mirror, control module for multi-function steering wheel, control unit in steering wheel (7.5A).
6. Central locking system (5A).
7. Back-up lights, speedometer vehicle speed sensor (VSS) (10A).
8. Open
9. Anti-lock brake system (ABS) (5A).
10. Engine control module (ECM): gasoline engine (10A); diesel engine, Model Year 2000 > (5A).
11. Instrument cluster, shift lock solenoid (5A).
12. Data Link Connector (DLC) power supply (7.5A).
13. Brake tail lights (10A).
14. Interior lights, central locking system (10A).
15. Instrument cluster, transmission control module (TCM) (5A).
16. A/C clutch, after-run coolant pump (10A).
17. Open.
18. Headlight high beam, right (10A).
19. Headlight high beam, left (10A).
20. Headlight low beam, right (15A).
21. Headlight low beam, left (15A).
22. Parking lights right, side marker right (5A).
23. Parking lights left, side marker left (5A).
24. Windshield and rear window washer pump, windshield wiper motor (20A).
25. Fresh air blower, Climatronic, A/C (25A).
26. Rear window defogger (25A).
27. Motor for rear windshield wiper (15A).
28. Fuel pump (FP) (15A).
29. Engine control module (ECM) gasoline engine (15A); diesel engine (10A).
30. Power sunroof control module (20A).
31. Transmission control module (TCM) (20A).
32. Injectors: gasoline engine (10A); diesel engine (15A).
33. Headlight washer system (20A).
34. Engine control elements (10A).
35. 12 V power outlet (in luggage compartment) (30A).
36. Fog lights (15A).
37. Terminal (86S) on radio, Instrument cluster (10A).
38. Central locking system (with power windows), luggage compartment light, remote/fuel tank door, motor to unlock rear lid (15A).
39. Emergency flashers (15A).
40. Dual tone horn (20A).
41. Cigarette lighter (15A).
42. Radio (25A).
43. Engine control elements (10A) including front and rear o2 sensor heaters
44. Heated seats (15A).
Fuse arangements in fuse bracket/battery:
S162. Glow plugs (coolant) (50A).
S163. Fuel pump (FP) relay/glow plug relay (50A).
S164. Coolant fan control (FC) control module/coolant fan (40A).
S176. Relays panel interior (110A).
S177. Generator (GEN) (90 Amp.) (110A).
Generator (GEN) (120 Amp.) (150A).
S178. ABS (hydraulic pump) (30A).
S179. ABS (30A).
S180. Coolant fan (30A).

Oxygen Senors
aka: o2 sensors
See "Oxygen Sensors"

FAQ - How to check 12V sources and Grounds

Example of checking engine bay grounds on a TT - Mk4 is very similar.

How to test for parasitic drain
Fabricate a test lamp consisting of a 12v lightbulb, socket, wiring, and alligator clips. With the battery fully charged, disconnect the positive cable and connect the test lamp between the positive battery terminal and the positive battery cable. If you have a parasitic drain, the lightbulb should be brightly lit.

Starting at the main fuse panel on the top of the battery, disconnect the fused red wiring one-by-one. When the lightbulb goes out (off), you've found the circuit causing the problem. If this circuit feeds the interior fuse panel located to the left side of the dashboard, reconnect the wire and start removing fuses one-by-one until the light goes out.

Hint, the wiring leads should be long enough for the lightbulb to reach the interior of the car so that you can observe it when you start removing fuses.

Engine Codes

Large list of engine codes and details
1.8t (and other) engines info

Block Codes

  • 06A
    * Came on 1.8t's with transverse arrangements (eg. golf, TT, jetta, Beetle Turbo, seat leon cupra R, A/S3, etc)
  • 058
    * Came on 1.8t's with longitudional arrangements (eg. Passat, A4, etc)

Head Codes

  • AQA
  • ARZ
  • AUM = AUQ
    * Very similar to AWP engine
  • AUM
    * TT225
    * 20mm Wrist Pins
  • AWP
    * Wideband
    * Small port
    * w/ SAI provisions
    * Came with VVT
    * Wideband
    * Late model = valve cover vent is 25mm OD
    * Early model (>= 2002) = valve cover vent is 20mm OD
  • AWW
    * Small port
    * w/ SAI
    * Past -> Early '01 was narrowband, Late '01 -> Present was wideband
  • ADR
    * Big Port
  • ADL
    Is the European version of the AEB engine code. The main difference is that it came in a mixture of big port and small port configurations. Was released exclusively in a longitudinal engine.
  • AJL
    * Big Port
  • AEB
    * Big Port
    * No port for combi valve
  • AGU
    * Big Port

Cross Section of an AEB
Special thanks to Speeding-G60

More AEB cross sections
See less See more
Ethanol Conversion (E85)
See "Fueling"


A discussion on the OEM exhaust

A discussion on performance, but quiet exhaust

Exhaust Size - Theory
Jay Kavanaugh said:

This thread was brought to my attention by a friend of mine in hopes of shedding some light on the issue of exhaust size selection for turbocharged vehicles. Most of the facts have been covered already. FWIW I'm an turbocharger development engineer for Garrett Engine Boosting Systems.

N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.

For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.

Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.

Again, less pressure downstream of the turbine is goodness. This approach minimizes the time-to-boost (maximizes boost response) and will improve engine VE throughout the rev range.

As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. 300 hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.”

As for the geometry of the exhaust at the turbine discharge, the most optimal configuration would be a gradual increase in diameter from the turbine's exducer to the desired exhaust diameter-- via a straight conical diffuser of 7-12° included angle (to minimize flow separation and skin friction losses) mounted right at the turbine discharge. Many turbochargers found in diesels have this diffuser section cast right into the turbine housing. A hyperbolic increase in diameter (like a trumpet snorkus) is theoretically ideal but I've never seen one in use (and doubt it would be measurably superior to a straight diffuser). The wastegate flow would be via a completely divorced (separated from the main turbine discharge flow) dumptube. Due the realities of packaging, cost, and emissions compliance this config is rarely possible on street cars. You will, however, see this type of layout on dedicated race vehicles.

A large "bellmouth" config which combines the turbine discharge and wastegate flow (without a divider between the two) is certainly better than the compromised stock routing, but not as effective as the above.

If an integrated exhaust (non-divorced wastegate flow) is required, keep the wastegate flow separate from the main turbine discharge flow for ~12-18" before reintroducing it. This will minimize the impact on turbine efficiency-- the introduction of the wastegate flow disrupts the flow field of the main turbine discharge flow.

Necking the exhaust down to a suboptimal diameter is never a good idea, but if it is necessary, doing it further downstream is better than doing it close to the turbine discharge since it will minimize the exhaust's contribution to backpressure. Better yet: don't neck down the exhaust at all.

Also, the temperature of the exhaust coming out of a cat is higher than the inlet temperature, due to the exothermic oxidation of unburned hydrocarbons in the cat. So the total heat loss (and density increase) of the gases as it travels down the exhaust is not as prominent as it seems.
Another thing to keep in mind is that cylinder scavenging takes place where the flows from separate cylinders merge (i.e. in the collector). There is no such thing as cylinder scavenging downstream of the turbine, and hence, no reason to desire high exhaust velocity here. You will only introduce unwanted backpressure.

Other things you can do (in addition to choosing an appropriate diameter) to minimize exhaust backpressure in a turboback exhaust are: avoid crush-bent tubes (use mandrel bends); avoid tight-radius turns (keep it as straight as possible); avoid step changes in diameter; avoid "cheated" radii (cuts that are non-perpendicular); use a high flow cat; use a straight-thru perforated core muffler... etc.”

Comparing the two bellmouth designs, I've never seen either one so I can only speculate. But based on your description, and assuming neither of them have a divider wall/tongue between the turbine discharge and wg dump, I'd venture that you'd be hard pressed to measure a difference between the two. The more gradual taper intuitively appears more desirable, but it's likely that it's beyond the point of diminishing returns. Either one sounds like it will improve the wastegate's discharge coefficient over the stock config, which will constitute the single biggest difference. This will allow more control over boost creep. Neither is as optimal as the divorced wastegate flow arrangement, however.

There's more to it, though-- if a larger bellmouth is excessively large right at the turbine discharge (a large step diameter increase), there will be an unrecoverable dump loss that will contribute to backpressure. This is why a gradual increase in diameter, like the conical diffuser mentioned earlier, is desirable at the turbine discharge.

As for primary lengths on turbo headers, it is advantageous to use equal-length primaries to time the arrival of the pulses at the turbine equally and to keep cylinder reversion balanced across all cylinders. This will improve boost response and the engine's VE. Equal-length is often difficult to achieve due to tight packaging, fabrication difficulty, and the desire to have runners of the shortest possible length.”

Here's a worked example (simplified) of how larger exhausts help turbo cars:

Say you have a turbo operating at a turbine pressure ratio (aka expansion ratio) of 1.8:1. You have a small turboback exhaust that contributes, say, 10 psig backpressure at the turbine discharge at redline. The total backpressure seen by the engine (upstream of the turbine) in this case is:

(14.5 +10)*1.8 = 44.1 psia = 29.6 psig total backpressure

o here, the turbine contributed 19.6 psig of backpressure to the total.

Now you slap on a proper low-backpressure, big turboback exhaust. Same turbo, same boost, etc. You measure 3 psig backpressure at the turbine discharge. In this case the engine sees just 17 psig total backpressure! And the turbine's contribution to the total backpressure is reduced to 14 psig (note: this is 5.6 psig lower than its contribution in the "small turboback" case).

So in the end, the engine saw a reduction in backpressure of 12.6 psig when you swapped turbobacks in this example. This reduction in backpressure is where all the engine's VE gains come from.

This is why larger exhausts make such big gains on nearly all stock turbo cars-- the turbine compounds the downstream backpressure via its expansion ratio. This is also why bigger turbos make more power at a given boost level-- they improve engine VE by operating at lower turbine expansion ratios for a given boost level.

As you can see, the backpressure penalty of running a too-small exhaust (like 2.5" for 350 hp) will vary depending on the match. At a given power level, a smaller turbo will generally be operating at a higher turbine pressure ratio and so will actually make the engine more sensitive to the backpressure downstream of the turbine than a larger turbine/turbo would.

Pseudo Exhaust for mk4 review
42 draft design
billy boat / APR

Aluminized Steel

2.25" (stock)

Jet-Hot (aka Ceramic)



Tip Style:

Exhaust Manifolds

See "Turbo's"


See "Cooling"

Fan Control Module
aka: FCM
See "Cooling"

Fan Switch
See "Cooling"

See "Pulleys"

Discussion of flywheel torque specs
* with special notes of ARP bolts, Race prep, etc

Fuel Injector
See "Fueling"

Fuel Pressure Regulator (FPR)
See "Fueling"

Fuel Pump (FP)
See "Fueling"
See "Electrical"

How to test a fuel pump in-car


1.8t typically has a BSFC of around .45-.58

How to repair VW fuel lines

Additives Calculator
* Use this to calculate adding additives like Toluene and Xylene to your fuel.

Comparison of the best fuel pumps

Common fuel pump upgrades on mk4 platform (fwd)
* Deatswerks DW65V fuel pump
* HFP-A35HV Performance 265LPH Fuel Pump
* Inline Walbro 255 Fuel pump
* Inline Bosch 044 fuel pump

Fuel Pump Voltage Diagnosis
Note: This test will allow you to jumper the fuel pump into working if the fuel pump relay were to die. As such, if you think that your fuel pump isn't working because your fuel pump relay is dead, try this first. Also, if you would like to test the voltage at the pump, use this method to jumper the pump on, then test the voltage at the pump terminals so that plug and wire losses are taken into account.

Note: Pins 87 and 30 are pretty easy to identify as they are the 2 fat ones perpendicular to each other

Method 1:
1) Remove the fuel pump relay (relay 409 under the dash)
2) Bridge pin 87 to 30. You should now hear the fuel pump running. Aka, the fuel pump is now seeing battery voltage.

Method 2:
1) Remove the fuel pump relay (relay 409 under the dash)
2) Use your finger to push the main relay contactor down onto the relay solenoid. You should now hear the fuel pump running. Aka, the fuel pump is now seeing battery voltage.

Fuel Pump Diagnosis
The resistance of a fuel pump's motor is a prime indicator of its health.
0 ohms - it's dead.
1-3 ohms - Normal Pump
High Resistance (>100 ohms) - Failed motor coils or basket terminal to pump issue

windings are bad and it will cause drivability issues.

Fuel pump issues due to the crank position sensor
The ECU shuts off the fuel pump if it doesn't get pulses from the crank position sensor; the purpose of this would be to reduce fire hazard in the event of a crash, by shutting off the fuel supply.

The OEM intake manifold injector inserts are made of plastic and are known to leak and crack over time. Verdict Motorsports has made billet parts (w/ o-rings) to replace the OEM plastic parts.
Verdict Motorsports Injector Cups
DIY for replacing injector cups

What power level is supported by a given injector size at a given fuel pressure?
Fueling and Injectors FAQ
* Covers Lines, Fittings, Check Valves, Tools, Fuel Pumps, Fuel Rails, Software, Caveats, and more
Injector FAQ
* Covers 1.8t injectors and cross references them with software
Converting to use E85
An MIT undergrad paper on E85 vs Gasoline - Very good reading on e85

aka fusible link

See 'electrical'


Mk4 A-Pillar Gauge Install
Mk4 A-Pillar Gauge Install
Mk4 Center Console Dual Gauge Install

Boost/Vacuum Gauge[/url]



How to test your wideband gauge sensor
Innovative Motorsports LC-1 Wideband Install
AEM UEGO - Very modern, self calibrating sensor. Highly recommended.
Innovate PSB1
* Logger + Boost Controller + Wideband ... Excellent product

EGT Gauge
Inexpensive EGT Probe/ Gauge set (used by Frankenturbo for their testing)

aka Ground Straps

See "Electrical"

See "Cylinder Heads"

Head Gasket
aka headgasket

Discussion on big bore head gaskets
Head Gaskets for different cylinder bores

This is the metal gasket that seals the head to the block. You can purchase these in the OEM bore size or various 'big bore' size to handle blocks that have been bored larger and are running larger pistons. A common piston upgrade is 83mm diameter.

Other engines commonly use thicker headgaskets to reduce compression by up to around a full point. This is generally so a naturally aspirated engine can handle the addition of forced induction. The 20v turbo engine that we are using came factory with a turbo. As such, it is running somewhere around 9.2-9.5:1 compression, which is perfectly fine for running on forced induction. Use of a thicker headgasket to increase displacement on this motor is not advised. If you want more displacement, then get it the normal way; bore, stroke, or both.

Heat Shielding, Heat Wrap, Etc
See "Coil Packs"

Heater Core Fittings

On the Mk4 the heater core lines come straight out of the firewall and often get in the way of top mount big turbos. Below are a few methods of dealing with this problem

90 Degree Heater Core Modification
* Useful for top mount turbo w/ 4" inlet

Ignition Amplifier
aka. N122
aka. Coil Pack Driver

See 'Coil Packs'

This part is seen in early 1.8t motors such as the Audi A4 and Passat's AEB engine. Early versions of the 1.8t had coil packs that did not have the ignitor circuit built in. As such, there was a digital 'switch' (mosfet style) that would translate signals from the ECU (5V logic) into signals for the coil packs (12v logic). This coil pack driver would get hot and as such, had a heatsink that was mounted in the airflow path for cooling purposes. People who use aftermarket intakes and whatnot who simply let the coil pack harness sit in the engine bay somewhere often have reoccurring issues of burning out this coil pack driver.

See Fueling

Discussion on velocity stacks
Ram air

Installing a Forge TIP on a mk4

"If you over oil an oiled-type aftermarket air filter, excess oil and dirt will get onto the hot film and damage the MAF. If you re-oil any aftermarket oiled air filter, just put a very thin bead at the top and let it migrate throughout the filter because any more will probably damage the MAF."

TIPs for mk4 k03s fitment
* SFS (euro brand)
* Creation Motorsport (euro brand)
* Forge
** Everything sits up a bit higher than it did before, and the engine cover may not fit properly afterwards
* Samco

Discussion on TIPs for mk4 k03s fitment

Velocity stacks

  • BPI
  • Blox


  • AEM Dryflow
  • K&N
  • ITG

Uni Filter makes very good oiled foam filters. They also make DIY filter panels that you can customize for special applications.

CAI + Anti-Hydrolocking bits
Filter on a turbo

Intake Manifolds

Bottom of AWP intake manifold

Intake Manifold Comparison Test by INA
Technical discussion on Intake Manifold Design

AWP / AGU Intake Manifold Comparison

Transverse Options:
* RMR (out of production) - Small/ Big Port
* ABD - Small Port
* Integrated Engineering - Big Port
* --need to fill in more--

Longitudinal Options:
* --need to fill in more--

Billet OEM Manifold Injector Seats
* Solves the cracked & Leaking injector seat issue. The stockers are plastic.

Intake Manifold gaskets


  • Felpro
    Part # _____
  • Victor Reinz
    Part # _____
  • Felpro
    Part # _____
  • Victor Reinz
    Part # _____


  • New South Performance Powergasket
    This is a discontinued part. The original powergasket was known to have some problems with warpage and only mediocre performance benefits. The Powergasket Plus has made improvements across the board.
  • New South Performance Powergasket Plus
    Thickness: _____
    Material: Proprietary
    Smallport - Part # GAS 005 - $65
    Bigport - Part # GAS 006 - $65
  • 034 Motorsports Phenolic Gasket
    Thickness: ____
    Material: Phenolic
    Small Port - Part # - $ ____
    Big Port - Part # - $ ____
    Transitional - Part # - $ ____

Harmonic Balancer
See "Pulleys"

Intercooling (AAIC, AWIC, etc)

Good read on a hybrid charge air cooling setup & Experiment
Ebay Intercooling (mk4) Thread
FMIC Showoff Thread

For an air-to-air intercooler a good rule of thumb is this...
* Stock SMIC will heatsoak with even a stock turbo. If you chip it it will definitely heat soak. This intercooler is just a little intercooler for daily duties. If you push your car, any upgrade is a good upgrade.
* TT225 dual SMIC. This performs similar to a single upgraded SMIC.
* SMIC - The best of these (generally considered the Tyrolsport SMIC) is good for up to around 275 WHP applications. Above that, it just heat soaks too fast
* FMIC - They make small FMIC's that fit under the bumper with little to no trimming or modifying. Generally these are the smaller FMIC's. These smaller units perform similarly to an upgraded SMIC. The larger FMICs can support very large HP applications depending on how you size them.


  • Treadstone
  • Garrett
  • Precision
  • Various chinese stuff off ebay

Mk4 FMIC Kits

  • APR 'U' style
  • CTS 450HP Kit
    * Designed for their top mount turbo kit + SEM intake
  • CTS 750HP Kit
    * Designed for their top mount turbo kit + SEM intake
  • Treadstone
  • Eurojet
  • Kinetic

Mk4 / TT Vented Fender Liner for SMIC
Note: These will require modifications into a mk4. Direct swap for a mk1 TT
Part #'s for the Auti TT vented wheel liners:
left: 8N0821171B
right: 8N0821172B
Vented Fender Liner Install - Useful for SMIC installations

Mk4 SMIC Kits
* Tyrolsport
* Pwrhaus

New-Beetle SMIC
* Tyrolsport
* Eurojet

B5 SMIC Kits
* TyrolSport UG SMIC Intercooler for B5 Passat/A4 1.8T - $749
* Ringer Apikol B5 A4 1.8T SMIC Kit - $550

Discussion on AWIC design
Discussion on choosing an AWIC core


OEM Oil Feed Line
Taken from Psi Concepts

This kit will fit on the following turbochargers and setups:
- PSi "Concept" and MHI Series turbochargers utilizing PSi's Signature Series exhaust manifold (T25/T3).
- Garrett T and GT Series turbochargers utilizing PSi's Signature Series exhaust manifold (T25/T3).*
- Garrett GT "Eliminator" Series (GTRS/GTxx) turbochargers utilizing the OE or AFM exhaust manifold.
- Borg Warner/KKK (K03/K04/Kxx) OEM-style turbochargers on an OE platform.
Will fit both B5 and B6 platforms, including 058 (AEB/ATW) and 06A (AWM/AMB).
* = Garrett T-Series (T25/T28) will require a different drain flange, which can be substituted upon ordering for no additional charge.

Oil Feed:
1 x 4' long -4 AN braided stainless steel Teflon oil feed line
1 x M12 x 1.5 to -4 AN adapter fitting (Audi Engine Oil Supply)
1 x M12 x 1.25 to -4 AN adapter fitting (for Borg Warner/KKK, MHI, and PSi Concept Series)
1 x M11 x 1.0 to -4 AN adapter fitting without restrictor (for Garrett T Series)
1 x M11 x 1.0 to -4 AN adapter fitting WITH restrictor (for Garrett GT Series)
4 x copper crush washers for adapter fittings
1 x 4 AN male to -4 AN female 90-degree adapter fitting with swivel

Oil Drain:
1 x 11.5" long -10 AN braided stainless steel Teflon oil drain line
1 x Universal T6061-6 aluminum drain flange (for Garrett GT, MHI, PSi, and Borg Warner)
1 x Gasket for drain flange
2 x M8 x 1.25 pitch fasteners (for Garrett GT Series)
2 x M6 x 1.00 pitch flanged fasteners (for PSi/MHI/Borg Warner/K03/K04)
1 x -10 AN to 1/2" NTP adapter fitting
1 x -10 AN to 1/2" NTP 90-degree adapter fitting
1 x Audi/VW 1.8T oil pan drain flange
1 x Audi/VW 1.8T oil pan drain flange gasket
2 x M6 x 1.00 pitch fasteners for oil pan drain flange

Coolant Supply:
1 x 20" long -6 AN braided stainless steel Teflon coolant return line
1 x 13" long -6 AN braided stainless steel Teflon coolant supply line
1 x -6 AN to 13mm barb adapter fitting (for 058 AEB/ATW block supply)
1 x -6 AN to M14 x 1.5 pitch banjo adapter fitting (for 06A AWM/AMB block supply)
1 x -6 AN to 10mm barb adapter fitting (for coolant return)
2 x -6 AN to M14 x 1.5 pitch banjo adapter fitting (to turbocharger)
1 x -6 AN male to -6 AN female 90-degree adapter fitting with swivel
6 x 13mm copper crush washers

MAF (Mass Air Flow) Sensor
S4 Wiki's EXCELLENT article on the MAF Sensor

The mass air flow sensor is a 'hot wire' sensor that measures how much it cools as air flows across it. Being that it also knows the cross sectional area of the MAF housing the mass of air flowing into your engine at any given time can be calculated. Also, it should be noted that this reading can only be accurate if the flow is uniform across the MAF housing. This means that your filter should be at least 3" or so from the sensor and should pass through a flow straightener screen (or equivalent). It should also be noted that you should not over-oil your air filter if you have a K&N style filter as it can leave oil deposits on the MAF sensor over time. This oil will impeded proper readings on the hot-wire sensor.

When you choose your software tuners will specify which element and housing size you must use. This is a critical piece of many pieces of software. Do not substitute different housing diameters or elements than what is specified.

There are two variables in our MAF's: 1) MAF housing diameter and 2) MAF sensor element.

* Most people agree that the 'black' wire is the MAF signal wire. This is commonly tapped for progressive water/meth injection, electronic boost controllers, etc.

From AWP:
Pin 1 :
Pin 2 : Blue/Yellow : 12V
Pin 3 : Green : Ground
Pin 4 : Red/ Violet : 5V
Pin 5 : Black : 5V Output Signal (Analog)

From S4 MAF (Hitachi):
Green/ Yellow : 12V
Violet/ Grey : 5V
Black/ Green : Ground
Green : Signal

MAF Housing
(Diameters are outside diameters)

  • 2.75" OD
    60mm ID = 2.36"
    Comes stock on most versions of the 1.8t such as the AWP
    Housing Part # _______
  • ??? OD
    70mm ID = 2.76"
  • 3" OD
    73mm ID = 2.874"
    Comes stock on B5 S4 & mk4 VR6
    Housing Part # 280 217 529
    Eurocode Billet 3" Housing
    APR Stg3/ 3+ Cast 3" Housing
    Where to get 3" MAF
  • ?? OD
    83mm ID = 3.27"

MAF Elements

  • AEB MAF Element
  • mk4 chassis 1.8t element
  • TT225 Element
  • mk4 chassis vr6 element
  • S4 Element
  • RS4 Element

Main Caps / Main Bolts
See "Crankshaft"

Manual Boost Controller
Aka "MBC"
See "Boost Controllers"

Motor Mounts

If you want to replace your motor mount bolts with non-OEM bolts, be sure to use Grade 10.9 bolts. These are stronger than stock.

Motor Mount FAQ

* Options & opinions
* False misfire due to stiff mounts

Transverse applications have:
* Pendulum Mount (aka Dog Bone Mount)
* Transmission Mount
* Engine Mount

For the mk4 body style, here are some notes on the engine mount.

Motor Mount Bracket -> Block:
* Stock bolt is a stretch bolt. Replace every time.
* If you want to use a non-stock bolt, replace with Grade 10.9 bolts with flanged head, zinc plated.
(1) M10 x 1.5 x 112mm
(2) M10 x 1.5 x 86mm

Motor Mount -> Motor Mount Bracket:
* Stock bolt is a stretch bolt. Replace every time.
* If you want to use a non-stock bolt, replace with Grade 10.9 bolts, zinc plated. Head type can be flanged head or you can use a standard head + hardened washer.
(2) M12 x 1.5 x 65mm

Motor Mount -> Chassis:
* Stock bolt is a stretch bolt. Replace every time.
* If you want to use a non-stock bolt, replace with Grade 10.9 bolts, zinc plated with flanged head.
* Bolt length can be longer. There is plenty of space under there.
(2) M10 x 1.5 x 60mm

Pendulum Mount (Center) -> Transmission
OEM Torque Spec = _PM me with spec_
Grade 10/12 Torque Spec = 20 ft lbs
(1) M10x1.5x112mm

Pendulum Mount (End) -> Transmission
OEM Torque Spec = _PM me with spec_
Grade 10/12 Torque Spec = 20 ft lbs
(1) M10x1.5x32mm

Pendulum Mount -> Subframe
OEM Torque Spec = _PM me with spec_
Grade 10/12 Torque Spec = 20 ft lbs
(2) M8x1.25x(45-55)mm

N249 (Diverter Valve Electronic Control Valve)
See 'Electrical'

Narrow band (Narrowband)
See 'Oxygen Sensors'


Comprehensive look at the 1.8t oil system (With a focus on the AMB Engine )

Engine Oil Discussion

Oil Pressure Relief Valve (in oil filter housing)
* This part prevents oil from draining out of the head when the car is off. If this valve gets stuck, the head will not get any oil and will suffer oil starvation damage to the cam journals and VVT.

Recommended Full Synthetics
As recommended by Chickenman35 ....

* Amsoil AMO 10w-40 would be an excellant choice.

* Amsoil full SAPS EFM Euro 5w-40. The mid SAPS AFL 5w-40 would also be good.

* Shell Rotella T6 5w-40. This is a diesel oil, but can be used in gasoline engines. Pros: Good level of phosphates and zincs. Great price point. Highly ranked at BITOG and most motorcycle forums ( Bikes are hard on oils as are diesels ) Cons: Obviously not tested for VW standards but that really doesn't mean a whole lot these days. Your cars out of warranty so that won't be an issue and it is
a proven product in the field.

* Motul 8100 X-Cess

* Any full group IV synthetics by Red Line, Motul, Total, Brad Penn, Joe Gibbs in a 5w-40 or 10w-40 weight.

Secondary Decent Choices
These are good oils, but they don't have the phosphates and zinc additives that keep our cam lobes and hydro lifter buckets happy.

* Castrol Syntec 5w40

* Mobil 1 5w40

* Mobil 1 10w30 (although I personally don't like the 10w oil)

Recommended oil filters

Discussion on oversized oil filters
* OEM PN # 068115561B (Mahle Brand) (Upgraded size filter per factory bulletin)
Note: Mann W 940/25 is equivalent to this OEM part number
* Wix 51191, Mahle OC51, and Purolator L30257 are good non-OEM alternatives


* Napa Gold (Rebranded Wix)
* Amsoil
* K&N
* Mobil 1
* Bosch Premium
* Purolator PureOne
* Fram Xtended Guard
* Hastings

Oil Pan

When replacing the oil pan, if you don't want to use the gasket sealer that the Bentley recommends and comes factory on the car you can use Felpro Model # OS30708R instead. It is a rubber gasket that will keep you away from that messy gasket sealer.

Also, when replacing the oil pan, don't overdo it on the gasket sealer. Excess sealer will fall off in the oil and can clog your oil pickup screen.

* Steel hybrid
* Baffled

* Magnetic Drain Plugs

Oil Squirters
See 'Blocks'
See less See more
Oil Temp Gauge

The 1.8t does not have an oil temp gauge from the factory. This is in reference to installing an aftermarket gauge.

A good spot for the oil temp sender is in the OEM drain plug
VDO m14x1.5 sender. Replaces the oil pan bolt, also the lowest point in the pan.

Oil Temperature

...add some information in on oil coolers

Oil Temperature Typical

Oil Pressure (Typical)

Cold Idle: ~80 psi
Cold 2k rpms: ~90 psi
Cold 3k rpms: ~100psi (pegs the gauge)
Hot Idle: ~24 psi
Hot 2k rpms: ~50 psi
Hot 3k rpms: ~70 psi
Hot at redline can still peg the gauge (100 psi)

Oil Pump

..needs OEM oil pump info here...
...needs info about oil pump chain tension noises/ problems...
Performance Oil Pump Kit

Oxygen Sensor

Oxygen Sensor Detailed Information
Another great oxygen sensor usage

Fused Version of the ECU - Handles oxygen sensor shorts that normally 'blow' the ECU

Simple Oxygen Sensor Test:
* Heater cold resistance at room temperature, with a multimeter between grey and white cable (H+, H-), and the sensor not connected to the Precision Wideband Controller, should be between 2.5 and 10 ohms
* When you are under boost your block 31 first value should be below ~.88
* When you are under decel your block 31 first valve should be above ~1.2
* When you are at idle your block 31 first value should be about 1

Narrowband -> Wideband Conversion
See "ECU"

'Wayne' Angle Block
* Fixes CEL for people running high-flow cats or no cats at all

* Rear o2 spacer

TT mk1
ATC - 180hp - narrowband
AMU - 225hp - narrowband

Audi A4
AEB - narrowband
ATW - ME7 Narrowband - Year 2000 only
AWM - ME7 wideband and was 2001 for B5

--not sure - a4 ---


TT mk1
AWP - 180hp - wideband
BEA - 225hp - wideband

Audi A4
AMB - wideband


Audi TT got wideband in late 2000 (build date) starting with engine code AWP.
A4 got wideband in ____??? starting with engine code ____
Mk4's got wideband in late 2001 starting with engine code _____
NB's got wideband in ____ starting with engine code ____

Fuse 43 protects the o2 sensor heater (and other stuff)

For AWP engine code

Front o2 sensor

o2 harness plug
Pin 3 is heater +
Pin 4 is heater gnd

Heater + is 12v with ignition keyed on

Ecu pin .. Harness Wire color .. o2 connector number ... o2 sensor wire color .. Purpose

52 .. grey/red .. 6 ... Red ... Heater +
71 .. black .. 2 .. Not connected
51 .. grey/white .. 5 .. Yellow ... Pump Circuit (adds and removes o2 from sensor)
70 .. green .. 1 .. Black ... Signal +
5 .. white .. 4 .. White ... Heater -

Relay 87A .. blue/red .. 3 .. Grey ... Signal Ground[/quote]

Parts Numbering

How to decode a Volkswagen Part Number

PCV System

In order to keep your fuel trims the following sensors (at a minimum)must be resistored:
* N112 (SAI/ Combi Valve Controller)
* N80 (EVAP)
* N75 (Boost Controller)

If you'd like to resistor other things like the SAI pump you can, but you don't have to.

You can resistor it yourself using 1 watt 330ohm resistors.

N249 Delete
nstevic01's SAI/N249/PCV/EVAP delete
Drilling a head so it can have a Combi Valve (and in turn a SAI system)

Delete kit for transverse applications

Throttle Pedal
Aftermarket Throttle Pedals(For Drive by Wire Cars
* Our cars use a throttle pedal with dual signals. This allows the ECU to cross check the data to ensure it is working correctly.

Pendulum Mount
See "Motor Mounts"


20V Piston FAQ

See "Wristpins"

Power Steering

Recommended power steering fluid: Pentosin chf11s (vag # G 002 000 A2)
Pentosin product sheet

* Deleting the power steering pump

Deleting the power steering simplifies the bay, frees up some power, and makes the steering heavier
EAA Engineering Power Steering Delete Kit (mk4)
* Increasing Steering Effort

Pressure Relief Valve
See "Oil"

Aka: Harmonic Balancer Pulley, Power Steering Pulley, Alternator Pulley

Why you should use a fluidampr - Exploding Crank Trigger Wheel Inside

Excellent explanation of vibrations, when to use a fluidamprs, and other considerations

4 Bolt to 6 Bolt Harmonic Balancer Conversion
* This is a great direct swap to better equip your car for high RPM operation.

Underdrive and lightweight pulleys
It is ok to run lightweight and/or under-driven (smaller) alternator and power steering pulleys.

The lightweight pulleys will reduce your rotating engine mass.

The under-driven pulleys will reduce the mechanical energy fed into the devices they're connected to. If you under drive your A/C, it's condenser pump cannot operate as powerfully so your A/C will not work as well. If you under drive your power steering you will not get as much power steering assist. If you under drive your alternator your alternator will not put out as much current and thus cannot charge your battery as quickly. Tip: Do not underdrive your alternator if you have lots of big audio amps and stuff in your car.

DO NOT use an under-drive or use a lightweight crank dampener pulley!!! This pulley has the very important job of balancing your rotating mass and is built the way it is because of the harmonics of our engine. You can damage your main bearings or worse if you use this part.

...There is one exception to my statements about the crank dampener pulley. If you get your rotating assembly balanced with your lightweight crank pulley, you can use it. BUT THAT IS THE ONLY CONDITION!!! To do this you must submit your entire rotating assembly to a shop that has a machine capable of spin balancing the entire assembly. It is essential to keep harmonics out of your crank, flywheel, and all the critical bits!

See "Connecting Rods"

Rod Bearings
[*] Calico Coated
[*] 034 anti friction
[*] Mahle Race

Secondary Air Injection

Excellent Generic Read on Secondary Air Injection


Section needs to be detailed...
- Knock Sensors
- Cam Position Sensor (CPS ...don't use the acronym...it's confusing)
- Crank Position Sensor (CPS ...don't use the acronym...it's confusing)
- Front Oxygen Sensor (Narrow or Wide Band) (4 or 5 wire)
- Rear Oxygen Sensor (Narrow band)
- Manifold Pressure Sensor (MAP)
- Intake Actual Temperature (IAT)
- Mass Airflow Sensor (MAF)
- Exhaust Gas Temperature Sensor (EGT)
- Coolant Temperature Sensor (CTS)
- Radiator Fan Switch
- Power Steering Switch
- Air Conditioning Pressure Switch

Shaved Bay
See "Deletes"

ME7/7.5 Software
See "ECU"

SMIC - (Side Mount Intercooler)
See "Intercooling"

Spark Plugs

DIY Replacing Spark Plug

Indexing Spark Plugs

How to read your spark plug (and tune your car by reading the spark plug[/url]

Rules of thumb:
* For stock motors use a spark plug with a NGK heat range of 6.
* For chipped or larger motors use a spark plug with a NGK heat range of 7.
* For stock motors or basic (stg1) chipped motors a platinum plug is recommended. It's long lasting and performs well.
* For high boost applications a copper or iridium plug is recommended. Do not use multi-prong plugs for high boost applications (>25 PSI). Copper performs well but should be changed every other oil change. It is easy to gap copper plugs. Iridium plugs are trickier to gap. NEVER put any pressure on the iridium tip!!! Even if it doesn't break you may weaken it and it can break off in your motor! Iridium plugs are long lasting and very good plugs, albeit at least 5x more expensive than copper plugs.

Common plugs:

* VW 101000063AAKT, iridium
* NGK PFR6Q, platinum

Chipped (1 step colder heat range)
--Good for everywhere from chipped to a 28 framed turbo
* NGK BKR7E (4644), copper plugs
* Denso IK22, iridium plugs
* NGK PFR7B, platinum plugs

Big Turbo (2 step colder heat range)
--Good for 30 frame or 35 frame turbos (or extreme setups on smaller turbos)
* Denso IK24, iridium plugs


* .032"

* .028

High Boost
* Start at .022 and keep regapping higher until you start seeing misfires...then close the gap a bit. Personally, I run a .026" gap on my car w/ BKR7e plugs running around 26 PSI boost.

Note regarding upgraded coil packs:
* Many people think that upgrading your coil packs to the fsi/tsi coils means that you can run a large .040 or so gap. This is not universally true. You can generally gap it larger due to the increased spark energy, but you need to discover this yourself. Each car is different. Start the gap at .028 and keep working the gap larger until you start seeing misfires under high boost. Then back the gap back down.

Note regarding worn spark plugs:
* Worn spark plugs put increased load on the coil packs. Worn spark plugs can contribute to coil pack failure.

Note regarding larger spark gap:
* Larger spark gap puts more load on the coil packs. Larger gaps can reduce the life of the coil packs.

Why not to use anti-seize on your spark plugs

NGK Reference Chart

Suction Jet Pump

Standalone Engine Management

  • 034 EFI
  • Lugtronic
  • Megasquirt


Swapping a 1.8t FSI , 2.0T FSI, or 2.0T TSI into a mk4

Throttle Bodies

Throttle Body Cleaning Tutorial

The best way to indentify a Bosch 70mm unit (at least from Audi , etc) is by looking for the arrow casted into the housing body.

DBW pinout
Pin 7 - 5v+ or TPS VCC
Pin 4 - Negative or TPS GND
Pin 5 - TPS or signal

INA Throttle Body Shootout

Size & Fitment
Size is the inner diameter.

Most adapter plates can be made with a 1/8" NPT tapped hole for W/M injection

* 1.8t stock
* VR6 24V
** -> Stock manifold : Requires adapter plate
*** INA carries this adapter

* Bosch
0 280 750 047
* Audi B5 S4
986 605 115 01
078 133 062
** -> RMR manifold : Requires adapter plate
*** INA carries this adapter
** -> SEM Manifold : Requires adapter plate
*** INA carries this adapter
* Porsche 986 (Boxster)
** "986 Porsche uses the same throttle body as the B5 Audi S4 just different TPS"
* B5 Audi S4 2.7tt
* C5 Audi A6 2.7TT
* Audi R8 4.2 V8
* Mercedes-Benz C320
* Volvo B5254T engine
* Likely others...


* R32

INA said:
There are actually 4 different versions of the "hemi" 80mm DBW throttle body.
Technically it should be called VDO 80mm unit since they are found on more vehicles that just Dodge Hemi's.
When you order one make sure it is the 805 or 801 so 5161805AA or 53032801AC (last 3 #'s of the Dodge part # as these have the throttle body lip for silicone but they are taller) . Do not get the 847 unit as that is the shallow unit but has no lip for a silicone hose so above 1.5 bar expect that silicone hose to blow off.
If you have anymore questions do not hesistate to send me an email.


* OEM Sources
** VR6 OBD1
* A6 2.8 V6
** -> Stock manifold : Requires adapter plate
*** INA carries this adapter

Thermostat Flange

This attaches to the block, 90 degrees to the side of the water pump. It seals to the block with an o-ring.

Use either the plastic OEM piece, which generally holds up very well.


Use the cast aluminum piece, which I imagine will hold up even better - $34.95 @ fixmyvw.com

aka Timing Belt
aka Check Timing

FSI Timing Belt Conversion Discussion
* This uses a spring based roller instead of the pneumatic roller that is stock on the 20v 1.8t

Discussion on Gates Kevlar Belt and Manual Tensioners

Timing Belt Job DIY

Timing Belt DIY - Golf/Jetta/TT/Jetta Mk4 - A4

Timing Belt DIY - Audi A4 - B6

Timing Belt DIY - Audi A4 - B6

Note: When doing your timing belt you will have to remove the motor mount on transverse applications. Please always replace the four OEM stretch bolts with new stretch bolts. Stretch bolts are called that because the STRETCH aka Torque to Yield. This means they can only be used once to achieve proper torque. If you reuse them they may not break, but they will not reach the correct torque spec.

Name brand vs. Chinese Roller
* This demonstrates the poor quality control of Chinese parts. The bolt for the roller was ~1/8" too short, which caused incorrect pressure to be applied, and in turn the bolt for the tensioner roller snapped while the user was driving. This cause the head to be trashed.

Don't cheap out on these sort of critical parts!

Standard Belt

The Continental brand timing belt that comes OE is a great belt. It almost never fails, is reasonably priced, is easy to source, and in general is a great option. The only place where people question it is in HIGH RPM operation. We're talking people who regularly turn over 8500 RPMs. At these RPM's there is fear of the OE belt stretching in the best case or jumping teeth on the crank in a worst case. However, the OE belt has been in high HP applications such as Speeding-G60's 9 second drag car with repeat success. This goes to show that the OE belt can definitely be used in high HP, high RPM applications.

The reasons for an uprated timing belt
Discussion on the benefits of uprated belts

This will cause your timing to be off (obviously the cam and crank aren't in TIME anymore). A car that isn't in exact time will be harder to tune and will be harder to run at maximum performance.

Tooth Strength:
Jumping a tooth could cause your timing to go off. Jumping a few teeth means you just wrecked your head or worse (depending on how fast the engine's turning when it happened + your luck at that moment). However, the OE belt, the RAI belt, and the INA racing belt do not have problems with this. Timing belt tooth shear is not a problem on this platform. If you are having wear issues on your belt it is likely for other reasons such as misaligned rollers causing the belt to rub on something. I've also seen where someone dropped a small 10mm nut down by the crank bolt, which wedged against the timing belt, and caused the belt to disintegrate as the nut filed it away. This just goes to show that you need to use care when working on or around your timing belt.

The uprated timing belts are rated to increase change intervals. Many users are getting over 100,000 miles out of their uprated belts with no to minimal signs of wear. NOTE: You should still check your timing belt every oil change or two. Just remember, the belt will generally outlast the tensioner. It is the tension that you are checking first and foremost. The condition of the belt is just as much of a concern, but less likely to cause failure than the tensioner.

Please note that the OE hydraulic tensioner can become dangerous long before the belt wears out. At this point, your change interval is determined by the life of the hydraulic tensioner. You have to replace this part as preventative maintenance. Failure of this part means your timing belt jumps and you wreck the head.

The manual tensioner conversion does away with the hydraulic tensioner. The manual tensioner is a parts bin pull from the old 16v 4 cylinder engines. It was a very reliable part with users reporting never changing it in the life of the engine (over 200,000 miles). Of course, the 1.8t has engine bay temperatures higher than the 16v motor and regularly turns more RPM's than most 16v motors, so I still conservatively recommend replacing the manual tensioner every 100,000 miles or at the first sign of timing belt wear.

Any unusual timing belt wear is generally an indicator of something that is wrong.

It is common for the timing belt to ride to the edge of the cam gear, but not OVER the edge of the cam gear.

If one side of the belt looks more worn than the other, this could be an indicator that your tensioner wheel/ bearing is going bad. Look into this ASAP. Replace the faulty part and the belt.

If a belt looks frayed it is likely that it is rubbing on something. I had a motor mount come loose and my belt was rubbing on the motor mount. Look into this ASAP. Repair the problem. Replace the belt.

If you hear squeaking or loud, unusual noises from the timing belt side of the engine, this could be a bad bearing in the tensioner, the idler pulley, or the water pump. A failure of any of these will cause catastrophic failure. Look into this ASAP.

History of the uprated belts

OE Belt:
The OE belt for the 1.8t was a continental belt. It has been used to much success and is a fantastic belt.

034 Motorsports Kevlar Timing Belt:
This is a kevlar reinforced belt that was commissioned by 034. It had multiple known failures and was pulled from the market. If you are using one it is recommended you change it for one of the other good brands.

INA Engineering Gates Blue Racing Belt:
This belt was commissioned by INA to Gates to make an 06A compatible timing belt from the Gates Racing line of timing belts. This belt is a performance belt in every sense of the word but is not Kevlar. When the belt was commissioned Gates did not make a kevlar timing belt. This belt is extremely popular and has been used successfully in many performance builds.

RAI Motorsports Gates Kevlar Timing Belt:
This belt was commissioned by RAI Motorsports to Gates to make an 06A compatible timing belt from the new Kevlar line of timing belts. This belt is of excellent quality and is very reliable.

Note: Even non-performance builds can use a performance timing belt. The performance timing belts offer improved reliability over the OE continental timing belts.

All Kits
* OE Belt (06A Block): Part # 06b 109 119a
* Gates Kevlar Belt (06A Block): Part # GR-T306RB
* 034 Kevlar Belt (06A Block): Discontinued due to failures
* RAI Kevlar Belt (06A Block): Part # RAI-12008MGT-K

* OE Belt (058 Block): Part # 058 109 119C

Standard Timing Belt Kit
* Hydraulic Tensioner w/ Idler Roller: Part # 06B109477
* Timing Belt Tensioner Roller: Part # 06B109243

Manual Timing Belt Kit
Discussion on Pneumatic/Hydraulic/Spring OE tensioner vs. Manual Timing Belt Tensioner

* Stud: Specs _____
* Nut: Specs ______
* 16v tensioner: part #051 109 243

* IE Tensioner Backing Plate: IE Part # _____
* IE Idler Roller: IE Part # ________

Replacement Parts for the IE Idler Roller:
* Lower Roller: Part # 06B 109 244

Common parts while you're at it...
* Motor Mount -> Frame: Part # _____
* Motor Mount -> Block: Part # ______
* ECS Motor Mount Bolt Kit: ECS Part # 038121119B
* Accessory Belt Tensioner: Part # _____
* Accessory Belt (w/ A/C): Part # 06a 260 849c
** This is made by Continental
* 2 x Coolant (G12 plus, 1 Gallon): Part # g012 a8g 1g
* Internal Water Pump (metal) (06A block): Part # 06a 121 011t
** See section "Waterpumps" for more details about waterpumps
* 87C Thermostat: Part # 050121113C
* Thermostat Housing: Part # 06A121121
* Thermostat O-Ring: Part # 038121119B

Parts for an OEM timing belt job on an 06a block motor
OEM Conti Timing Belt: Part # 06b 109 119a
Hydraulic Tensioner w/ Idler Roller: Part # 06B109477
Timing Belt Tensioner Roller: Part # 06B109243
Conti Accessory Belt w/ A/C: Part # 06a 260 849c
1 Gallon G12 coolant (OEM or Pentosin): Part # g012 a8g 1g
USRT Metal y-pipe (because this part likes to break): Link
Hepu water pump : Part # 06A121011L
New bolts - Motor mount to block
New bolts - Motor mount to frame
New motor mount if the insert is worn out

Turbo Intake Pipe
aka TIP

See 'intake'

Torque Specs

Torque Spec Thread


LSD (Wavetrac) and Fork upgrade

o2j / 02a modifications to improve high RPM shifting

02m shift fork installation tutorial

Magnus Hydraulic clutch launch control device
Electronically controlled solenoid that slows the release of the clutch. This keeps you from 'dumping the clutch' and instead has a pre-set (adjustable) ability to feather the clutch during a launch

02m Tilton Clutch Upgrade

Falcon Transmission - Great custom clutches .. See here, post #9 for some details

My Transmission FAQ
How to adjust shift linkage if you have a broken home position switch
O2J Transmission Fluid Change
Performance Shifting Solutions
Performance Transmission Solutions
5 speed to 6 speed swap (mk4)
SQS Racing - Performance Transmission Offerings
APTuning / G-Force Transmissions - Upgraded Gearsets and Diffs

Limited Slip Differential
Consider one of these for all BT builds ESPECIALLY if you don't have Quattro. Once you get over 250HP you need more grip or it's all 1 wheel burnout city. The three majors are all solid offerings
1) Quaiffe
2) Peloquin
3) Wavetrac

Mk4 shifter
Shift tower replacement

Shifter relay ball
* Diesel Geek Shifter Relay Ball repair

* Upgraded Secondary Slave Cylinder Line (Braided stainless)
* Aluminum, stainless, or delrin shifter bracket bushings
* Aluminum, stainless, or delrin shifter end link bushings
** 42 draft part
* Shifter relay bushings
** 42 draft part
* Short throw kits of various forms
** Diesel Geek Sigma 6 Kit
** TT stock shifter
** Many other vendords

Spider Gears/Side Gears Break
Cross Shaft Breaks
Cross Shaft Roll Pin Breaks & Corss Shaft Punctures Case
Rivet Breaks and Punctures Case
* Use high strength bolts instead of OEM rivets
Shift fork breaks
* Use welded, reinforced shift fork
Case breaks at pinion
* Use reinforced pinion brace

Transmission Mounts
See "Motor Mounts"

Trigger Wheel
See "Crankshaft"

Discussion on Small Tubing and Vacuum Tubing
See less See more

Frankenturbo Setup thread

Rebuild Turbos
Midwest Turbo Connection

Frankenturbo Metallurgy vs BW Metallurgy
Short Answer: The Frankenturbo turbine housing is made of a lower grade iron. Everything else is the same. Good stuff.

Adjustable internal wastegate bracket

Manifold Removal Advice

Garrett Turbocharger Installation Advice
* Note: The advice in this thread is applicable to all turbos and should be followed for any turbo install

T3 to T4 adapter

Transverse Big Turbo Kits w/ notes

Longitudinal Big Turbo Kits w/ notes

  • Frankenturbo F4T
  • Frankenturbo F23
  • Pag Parts Bottom Mount
    Available for FWD and AWD
  • APR stg3/ stg3+
    Available for FWD and AWD
  • CTS Top Mount
  • RAI Motorsports Borg Warner EFR

Oil Restrictors
Most dual ball bearing turbos require an oil restrictor. Most (if not all) journal bearing turbos do not require an oil restrictor. This is because journal bearing turbos work by pushing high pressure oil between the bronze parts causing them to glide nicely WHILE UNDER OIL PRESSURE. If you starve a journal bearing turbo of it's oil IT WILL DIE. You can starve a turbo by either not giving it enough feed (-4AN recommended) or by not allowing the oil to leave easily (-10AN recommended). With a DBB turbo the bearings just need to stay lubricated. They roll all on their own. Too much oil pressure can blow the bearing seals...which means oil will start getting into your intake and exhaust...aka black smoke and/or an oil coated intake.

Garrett Series BB Turbos use a .035" orifice. -4AN restrictor. Use -4AN feed line

Turbo Upgrade Parts

  • Treadstone Compressor Housings for EFR Turbos
  • HTA Compressor 'Aero' Wheels
    Readily applicable for the Garrett GT28, GT30, GT35 turbochargers
  • Tial V-Band Compressor housings for Garrett Turbos
  • V-band Turbine Housings for Garrett Turbos

Mounting Hardware
Non-Vband manifolds and turbos use studs, washers, and nuts to secure them together. There are other fastening aids such as locking plates, locking tabs, tac welding, safety wire, and others. I'll go over some good techniques and parts. The grades of these are also very confusing for many people so I'll put together a good list.

Discussion on loose turbo nuts

Bolt/ Nut Locking Liquids and Pastes
*Loctite (or equivelant) (Needs to withstand >1200F continuous heat)
* Exhaust Putty on bolt head or nut will reduce chance of it coming loose
Discussion on using exhaust putty

* Grade 12 Stainless Bolts (These are good for GT flange -> downpipe. Not for Turbo -> Manifold)
* Stage 8 Fasteners
* For stock turbos use M10x1.5, 50mm long . Grade 8.8
* For turbos such as the godspeed, Kinetic, Etc use M10x1.5, 75mm long. Grade 8.8
** Note: may be applicable to ATP and clones):
- Need to install turbo to manifold first, then manifold to cylinder
- Manifold nuts virtually impossible to tighten (casting too tight around nuts).

* ARP Black Oxide Studs (Think of these as common exhaust studs ++. No defective metals here)
* Grade 8 Common Exhaust Studs (They can deal with the heat. Do not use SS)
* Stage 8 Fasteners

* Nordlock (use mild steel nordlocks. The SS nordlocks expand more and will loosen)
* Hardened flat style (you want these to stay rigid. A non hardened washer is more apt to warping)

* Eccentric Zinc + copper plated exhaust nuts
* Grade 12 nut
* High temp Jet Nuts
* Stage 8 Fasteners
* Flexloc

Locking Tabs
INA Locking Tab Plates


Nissan S15 - GT25/ GT28 OEM gasket for GT 5 bolt flange
Nissan S15 GT25/ GT28 OEM gasket for T25/T28 flange
* These Nissan gaskets can be purchased from Nissanraceshop.com or thenismoshop.com
OEM turbo -> Manifold gasket is the best gasket for the ko3 range of turbos (scotch brite the surface first)

Talking about blowing up turbos and engine damage
Check out your compressor wheel and make sure it's intact. On journal bearing turbos, when the turbine breaks, there is nothing that holds the shaft in place. The thrust bearing prevents 'walk' when the entire shaft assembly is intact. When you lose one of the wheels, that shaft is free to go wherever it wants unlike a ball bearing turbo where the shaft is actually pressed into the ball bearing assembly and held in place. If the turbine wheel breaks in this scenario, the comp wheel stays in place and is typically not damaged. Compressor wheel damage can wreak havoc on your motor contrary to what ppl say. It doesn't just break off in pieces and gets filtered by your IC. It pulverizes into fine powder at times and bonds to valve seats, to cylinder walls and rings. This is worse case scenario and depending how much compressor housing and wheel damage we are talking here, it can be a real scenario. Have seen it many times. It's a real lesson that is learned the hard way when ppl want to try a cheap turbocharger with questionable build quality thinking that it doesn't hurt anything when it blows (this is not aimed at your turbo just a general statement)... Anyhow, I am not meaning to bum anyone out here. Just providing a little bit more clarity on a very real issue.
Common Big Turbos and some notes on them

  • KKK
    * K04-001
    K04-001 FAQ
  • Precision
    * Precision Turbo Direct Fit Series - Direct fit from Garrett Turbos
    -- HP GT3562R
    || w/ Billet Wheel
    * HP 4000 Series
    -- HP 4957
    * HP 5000 Series
    -- HP 5031E
    -- HP 5457
    -- HP 5557
    -- HP 5757
    -- HP 5857
    || w/ Billet Wheel
    -- HP 5865
    -- HP 5957/62/65
    * HP 6000 Series
    -- HP 6057
    || w/ Billet Wheel
    -- HP 6157/62/65
    -- HP 6262/65
    || w/ Billet Wheel
    -- HP 6365
    -- HP 6765
    || w/ Billet Wheel
    -- HP 6765/HPQ
    * HP 7000 Series
    -- HP 70HPQ/HPS
    -- HP 71HPS
    -- HP 72HPS
    -- HP 74HPS
    -- HP 76HPS
  • Garrett
    * Pag Parts Billet PPT 71B-SS (3071 derivitive w/ your choice of journal or bb flavors)
    * GT Ball Bearing Series
    * GT Journal Bearing Series
    * T Series
  • Borg Warner EFR Series

    Note: Keep EGT's under 1700F or you will run into serious reliability issues. This is an official warning from Borg Warner. Exposing the turbo to these EGT's can cause the Gamma Ti turbine wheel to let loose.

    * EFR
    * Bullseye Power S200 Series
    * Bullseye Power S300 Series

Turbo Bracing

Valve Covers
Thread talking about differences in the various valve covers
Installing an AGN valve cover

IE -10AN Valve Cover Breather Adapter

*Loctite 68015 10-Ml Retaining Compound 680 High Strength
-- Use acetone to clean parts first, then smear some of this on before installing the IE valve cover fitting to ensure a long term, 100% seal

Vacuum System
The vacuum system is extensive on the 1.8t engine. It includes the PCV system, the brake booster system, the EVAP system, the crankcase ventilation system, the SAI (secondary air injection) system, and the valvecover ventilation system. The 1.8t does not have an EGR valve, it has a combi valve (for emmissions).

It is common for people to simplify and/or delete parts of the vacuum system. They generally do this for aesthetic reasons (too many hoses in stock engine bay) or reliability reasons (too many hoses to crack or parts to break). In reality, the stock vacuum system works very well. You should keep the majority of it functioning correctly. There are ways of improving the reliability of it though.

Discussion on catch cans and stock vacuum system

AEB Vacuum System
* This is the simplest form of a vacuum system for the 1.8t engine while keeping all emmissions systems in place, puts a correct amount of vacuum on the rings, and minimizes failure prone parts. If desired, this system can be used for an excellent catch can system if you add a catch can between #8 and #15 in the diagram


Discussion on incorrect valve spring installation -- Cliffnote: It can break valve stems
Valve Selection Discussion
How to remove and install valve stem seals and Valve Guides

Installing new valve guides

Benefits of 'oversized' valves, what size oversize valve to go with (+.5mm, +1mm), use on intake and use on exhaust, and the work required to use an oversized valve

* Oversized valves tend to sell for the same price as non oversized valves.

Single groove vs. Triple Groove valves


Stock Exhaust Valve Specs

Head Diameter: 29.9mm
Stem Diameter: 5.96mm
Overall Length: 103.92mm
Tip Length: 5mm
26 degree Flo. , Triple Groove

Stock Intake Valve Specs

Head Diameter: 26.9mm
Stem Diameter: 5.97mm
Overall Length: 105.1mm
Tip Length: 5mm
24 degree Flo. , Triple Groove

Comparison of intake valve materials
...need some info. Are they all made of Stainless?

Comparison of exhaust valve materials
Valve Materials @ Precision Tech

Super Alloy:
Ferrera said:
Our super alloy valves are a custom blend material, but are based on Nimonic 80A as the base material.

They are generally 2 piece valves, but the process of joining the materials occurs before valve forging at the raw material stage. We do this to optimize the best material for the parts of the valve. On issue with all the super alloy type high nickel materials is that they can not be heat hardened, so if we made the whole valve out of this material, it would require a lash cap on all motors that run rockers
...could someone chime in with some Inconel tidbits?

Hollow Stem, Sodium Filled:

* Porsche and RUF use sodium filled exhaust valves in their high performance engines.
* Ferrera does not offer these for our application.
* OEM valves are made from this style. However, people have been known to 'drop' OEM exhaust valves...that is one of the benefits to upgrading to an aftermarket exhaust valve.

Intake Valve Manufacturers

  • Ferrera
    PN: 51556P
    Material: Super Alloy
    Mass / Valve: _____
    $316 / set
  • Ferrera +1mm
    PN: 51557P
    Material: Super Alloy
    Mass / Valve: _____
    $ _____
  • Ferrera +1mm
    PN: F1085P
    Material: Hollow Stem, Sodium Filled
    Mass / Valve: _____
  • Supertech
    Mass / Valve: _____
    $239 / set
  • Supertech Single Groove
    PN: _____
    Mass / Valve: _____
    $260 / set
  • Supertech Single Groove +1mm
    PN: ____
    Mass / Valve: _____
    $270 / set
  • AE
    PN: ______
    Mass / Valve: ______
    PN: 058109601C
    $10 / per (12 needed) ... $120 / set
  • Techtonic (also available in single groove)
    PN: 109 119
    Mass / Valve: ____
    Material: Stainless, black nitride treatment
    $28 / per (12 needed) ... $336 / set
  • Techtonic +1mm, single groove
    PN: 109 119x
    Mass / Valve: ____
    Material: Stainless, black nitride treatment
    $29 / per (12 needed) ... $348 / set
  • TRW
    PN: 058109601C
    Mass / Valve: _____
    $16.70 / per (12 needed) ... $200 / set
  • Osvat
    PN: 058109601CIT
    Mass / Valve: _____
    Material: Stainless
    $10 / per (12 needed) ... $120 /set

Exhaust Valve Manufacturers

  • Ferrera
    PN: _____
    Mass / Valve: _____
    Material: Super Alloy
    $282 / set
  • Ferrera +1mm
    PN: F1555P
    Mass / Valve: _____
    Material: Super Alloy
    $36 / Valve (12 needed) ... $432 / set
  • Ferrera +1mm
    PN: F1084P
    Mass / Valve: _____
    Material: Hollow Stem, Sodium Filled
    Mass / Valve: _____
    $ _____
  • Techtonics (also available in single groove)
    PN: 109 120
    Material: Inconel
    $ 34 / per (12 required) ... $408 / set
  • Techtonics +1mm , single groove
    PN: 109 120x
    Material: Inconel
    Note: Single Groove Keepers included
    $ 40 / per (12 required) ... $480 / set
  • Supertech
    $160 / set
  • Supertech
    Material: Inconel
    $260 / set
  • Supertech Inconel Single Groove
    $280 / set
  • Supertech Inconel Single Groove +1mm
    $290 / set
    PN: 058109611EIT
    Material: Head 21-4N + Stem X45CrSi9-3 . Stem Chromed
    $20 / Valve (12 needed) ... $240 / Set

Valve Seats
Valve seats get beat up by high-revving engines, high spring rates, and by high mileage. A good sealing valve seat is essential to having a tight seal in your cylinder and making power.

Intake Valve Seat Manufacturers

  • Integrated Engineering
    Bronze Alloy, better than stock
    ~$20 / seat (12 needed). $240 / set

Valve Stem Seals

Intake Valve Stem Seal Manufacturers

  • Integrated Engineering
    PN: _____
    $0.69 / per (12 needed) ... $12 / set
  • Hebmuller
    PN: 036109675A
    ??? material
    $2.43 / per (12 needed) ... $29 / set
  • Elring
    PN: 036109675
    ??? material
    $2.10 / per (12 needed) ... $25 / set
  • Victor Reinz
    PN: 036109675
    ??? material
    $2.10 / per (12 needed) ... $25 / set

Exhaust Valve Stem Seal Manufacturers

  • Integrated Engineering
    PN: _____
    $0.99 / per (8 needed) ... $8 / set
  • Hebmuller
    PN: 036109675A
    ??? material
    $2.43 / per (12 needed) ... $29 / set
  • Elring
    PN: 036109675
    ??? material
    $2.10 / per (12 needed) ... $25 / set
  • Victor Reinz
    PN: 036109675
    ??? material
    $2.10 / per (12 needed) ... $25 / set

Valve Guides

Valve Guide Manufacturers

  • Integrated Engineering
    PN: ____
    Bronze Alloy
    $10 / guide (20 needed) ... $200 / set
  • Techtonics Tuning
    PN: 109 235
    silicone bronze
    $6.50 / guide (20 needed) ... $130 / set
  • Canyon
    PN: 058103419
    ??? Material
    $4 / guide (20 needed) ... $80 / set
  • Supertech

Lifters aka Cam Followers

Solid lifters
Solid lifters reduce the possibility of valve float due to the hydraulic lifters. However, you pay for this high revving with increased lifter wear, increased precision required during assembly, needing perfectly fitting lash caps, and lots of extra engine noise while running.

Most high horsepower 1.8t's will NOT need solid lifters. It it not recommended to move to solid lifters for most BT applications.

A note from a very fast CQ 1.8t tells stories of split lash caps, split shims, adjusting spring pressures, dealing with bind....generally a real pain in the butt.

Exhaust Cam Follower Manufacturers

  • INA
    PN: 058109309E
    $13 / per (8 required ) ... $104 / set

Intake Cam Follower Manufacturers

  • INA
    PN: 058109309F
    $14.70 / per (12 required) ... $176 / set
  • Meyle
    PN: 058109309F
    $18.95 / per (12 required) ... $227 / set

Valve Springs
Valve Springs, spring rates, etc

Valve springs & Valve Spring Retainers
Do you have to match the valve spring retainer mfg to the valve spring company?

Valve Springs, spring rates, etc


  • Ferrera Springs
    Intake Spring Rate = ???
    Exhaust Spring Rate = ???
    Titanium Retainers
    ~$797 / set
  • Supertech
    Intake Spring Rate = ???
    Exhaust Spring Rate = ???
    Titanium Retainers
    $450 / Set
  • Integrated Engineering
    Intake Spring Rate = ???
    Exhaust Spring Rate = ???
    Titanium Spring Retainers
    ~$650 / set
  • Techtonics Tuning
    Intake Spring Rate = ???
    Exhaust Spring Rate = ???
    Titanium Spring Retainers
    $495 / Set

Valve Jobs
DIY vs. Professional vs ... valve 'jobs'. Also, notes and costs for a 'three angle valve job'

AKA: Internal Wastegate , External Wastegate

How to size a wastegate or blow off valve

Internal Wastegate Options


Internal Wastegates, External Wastegates, Dump Tubes, Wastegate Actuators, Etc

Internal Wastegate Wastegate Actuators
OEM Internal Wastegate teardown picture

Common mods
* 'Cranking' the wastegate
This means you are pre-loading the wastegate rod so the spring tension at rest is higher. This means for the same duty cycle of your boost controller, your turbo will reach higher boost. This also means that the wastegate flap can't open as much as it normally can, which can lead to boost creep. Boost creep is when there is more backpressure behind the turbo than the turbo can bypass and in turn, it causes boost pressures to go higher than you want them to.
* 'Spring mod'
This involves adding external springs to the wastegate actuator rod such that it keeps the wastegate flap held down more securely without losing any wastegate rod travel, as you would have if you had 'cranked' the wastegate actuator

External Wastegates
* Tial 38mm
Vband or Tial flange
Supports up to 400 HP (or 800 HP w/ a divided flange)
* Tial 44mm
Supports up to 750 HP
* Tial 60mm

Wastegate Actuator
See 'Wastegate'

Note: Wastegate Actuators are only used on internally gated turbos.

Vehicle Identification Number

Decoding what your VIN means

Water/ Meth Injection
Water/Meth Injection FAQ
Water/Meth Tuning

Nozzle Size Calculator

Mixing your own 50/50 Water/Meth
50/50 Water/Meth is by 50% water, 50% meth by weight
Methanol is 6.6lb/US gallon, water is 8.33/US gallon
Methanol should be stored in a HDPE container

For a 2 or 2 1/2 gallon bottle:
102 ounces of distilled water with 128 ounces (1 gallon) of methanol, which fits conveniently in a 2 or 2-1/2 gallon fuel container.

10bottles of HEET and 1gal of DISTILLED water will give you roughly your 50/50 by weight

Meth= .825oz per fluid oz
Water= 1.04375oz per fluid oz

58.575oz Meth / 59.493oz Water = 49.6% meth/50.4% water

aka. Vehicle Speed Sensor

This sensor outputs a square wave in relation to the rotational speed of your axles. It affects your speedometer, odometer, trip computer, and cruise control.

VSS for TIP to 5-speed swap

aka. Variable Valve Timing

This is an electro-hydraulic device that advances the cams 22 degrees on demand. This is used for both emmissions and performance purposes by the OEM and aftermarket.

Using VVT to make power - and is a good primer on what VVT is on the 1.8t

Notes about cam chain tensioner seal

Water pump

Very good discussion on metal vs. 'plastic' water pumps

On internal waterpump cars (06A blocks) the stock 'plastic' waterpump is notorious for the impeller self destructing and in turn, causing your car to overheat.

As such, this has brought to light the options in waterpumps. Here is the rundown from a VW mechanic who has dealt with lots of different pumps...

2.Geba--plastic/German,OK,but have had leakers. Has a bit of a rough mold compared to the OEM.
3.GRAF=crap,made in Italy. Has been known to leak through the shaft seal
4.Solari=OEM for BMW,total crap,had one fail at 7K and wipe out valves on a Audi 3.0
5.OEM=plastic and hit or miss,seen some fail at 70-80K some leak at 30K,total crapshoot,but decent.
6.Hamburg Technik--I have seen these but would never use one,made in China
7. Autolite--yes they make a water pump for VW,it totally sucks,pressed steel impeller,garbage
8. Hepu--the bomb,99% reliability,MADE IN GERMANY.

As such, for all intents and purposes, consider the HEPU brand water pump your go-to pump. Consider Lasso, Geba, and OEM all decent alternatives.
Anything else, stay away.

Another point of failure is leaking at the seal. Even if the impeller is in good shape, no one likes their car to mark their territory. As such, follow the recommended water pump brands above.

See 'Engine Overview' (at top)

Weight Reduction
Mk4 Weight Reduction

See 'Oxygen Sensors'

Wrist Pins

Tool Steel vs. Mild Steel
Good thread on this
* General rule of thumb according to IE and JE is that mild steel is good for
See less See more
More stuff here 7
Updated section on throttle bodies. If anyone wants to step up and fill in the rest of the details it would be much appreciated.

Started section on big turbo builds. PM me if you have a good candidate for me to put in there. Give me a link plus a quick summary of the build.
What engine codes am I missing in that section?

What engine codes have provisions for combi?

Are exhaust ports different on any of the heads?

Are there any other big port engine codes?
Tons more stuff added. If anyone wants to add any more stuff just let me know and I'll put it in.

This FAQ is becoming more and more complete.

On the same note, if you see places to improve it just let me know and I'll do that too.

Alphabetize and cross reference maintenance procedures.
great stuff

THX a lot
this was information i am looking for :)
Awesome thread here. Some info I found while chasing my tail on the stock boost curve for my aww. http://forums.subdriven.com/showthread.php?909130-Stock-1.8T-Boost-numbers

Delete this post once you've reviewed the link.
Awesome thread here. Some info I found while chasing my tail on the stock boost curve for my aww. http://forums.subdriven.com/showthread.php?909130-Stock-1.8T-Boost-numbers

Delete this post once you've reviewed the link.
Thanks. Added the best graph outa that thread to the FAQ
You can get the Polydrive tool from SEARS! It's a whopping 17 dollars!
You can get the Polydrive tool from SEARS! It's a whopping 17 dollars!
yep, i was looking at one earlier today, but i got ahold of a snap-on one locally :thumbup:
There are lots of spots that need more info.

Please PM or post here if you have information to contribute.
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