Carbon Buildup on MK7 ?'s

99651 Views 223 Replies 87 Participants Last post by Diggs24, Sep 27, 2021

PurWhtGTI

Discussion Starter · Nov 10, 2015

DI Valve Carbon build-up Preventive Maint.

Before purchasing the new GTI My Bride and I where thinking about purchasing a PU. While investigating the GM Twins and Ford PUs an interesting issue came apparent.

Carbon buildup on intake valves due to fuel not being sprayed onto the back side of the valves any longer thus keeping them clean. It seems that this is one of the down sides of DI.

http://www.autoguide.com/auto-news/...a-problem-with-direct-injection-engines-.html

From what I can gather it seems that it seems to be caused by oil vapors from the PCV valve system collecting on the back side of the valves and being cooked onto the hot surface. That maybe one of the reasons that VW is very specific about the specs of the oil used is to help keep this from happening.

Using a quality fuel wouldn't seem to make a difference as the fuel is sprayed into the combustion chamber instead of the intake manifold leading to the back side of the valves like MPI systems.

Anyone have any thoughts on a valve cleaning system that could be done say every other oil change to keep this in check as a preventive maintenance ?

41 - 60 of 224 Posts

jdfast

· #41 · Jun 25, 2016

Doing some research on maintenance of GTI, and I noticed in the older versions, carbon buildup on the intake was an issuie (for all direct injection cars including the lexus IS 250)

The Mk7 in the usa is direct injection ? whereas the european model is multi port injection which helps prevent the carbon buildup?

Are my assumptions true? If so, how much does it cost to clean the intake ($500-$700), from what I gather, there is not much you can do to prevent, but the Italian Tuneup Helps

http://shopdap.com/vw-audi-fsi-tsi-carbon-buildup-on-intake-valves/

"While many VW and Audi engines seem to have issues around 60k miles or more, we have heard of other manufacturers have carbon issues as low as 30K miles. "

If I can go 60K before I need to do this service, I could live with it, but not thrilled.

Any input from gti owners out there concerning carbon buildup?

See less See more

gukin

· #42 · Jun 25, 2016

I've been on this forum for several years, there is a lot of speculation but I've not read anyone with a MKVII requiring an intake cleaning.

euro16v

· #43 · Jun 26, 2016 (Edited)

North America cars still do not get port injection along with the direct injection, so carbon build up will still be an issue over time with these cars.

GTINC

· #44 · Jun 26, 2016

euro16v said:
North America cars still do not get port injection along with the direct injection, so carbon build up will still be an issue over time with these cars.

The purpose of MPI is not for "carbon buildup". It is for passing emissions. Uninformed folks on the internet made this idea up.

Akakage

· #45 · Jun 26, 2016

euro16v said:
North America cars still do not get port injection along with the direct injection, so carbon build up will still be an issue over time with these cars.

A fact-free statement without any proof/data/TSB links. Jury's still out on this.

SimplyVolks90

· #46 · Jun 26, 2016

Like was mentioned above, jury is still out. I too have not read anything about carbon buildup anywhere fot the MK7.

Sent from my SM-T330NU using Tapatalk

sgessler2011

· #47 · Jun 26, 2016

For what its worth, and stating that this isn't proof:

My MK6 GTI tailpipes would be black and sooty with days of cleaning. The MK7 GTI does not have this same behavior. My observations are that there is clearly less carbon soot making its way to the exhaust outlets.
Only time/miles will tell.

VW also just announced that they will be installing soot filters on their gasoline engines.

http://www.vwvortex.com/news/volksw...t-reduces-particulate-emissions-by-90-at-agm/

rbwalt

· #48 · Jun 26, 2016

carbon build up

the Mk'7s will suffer from carbon build up. it just will take some miles. all direct injection cars suffer from this. some probably worse than others. i have read that some manufacturer's are trying to solve the problem by adjusting intake timing. carbon build up at last reading ford had no answer yet to eco boost engine carbon build up other than replacing the head/ intake system.

IowaGTI

· #49 · Jun 26, 2016

So even a separator won't totally alleviate the issue. Has anyone totally removed the crank-vent system or routed it in another way?

jdfast

· #50 · Jun 27, 2016

tks for the info.

Any guess/estimate, how often you need this service and cost ($700?) I tend to keep my cars over 10-15 years, but might rethink about leasing a gti. The only prevention (or should I say reduction in carbon buildup), is the Italian Tuneup, I guess I could live with that

gtimaneg

· #51 · Jun 27, 2016

(Ill just copy a post I made on another form)

I have removed a total of two manifolds of the new Gen 3 E888 GTI 2.0T

First vehicle had 15k on it and a stuck open injector. Customer was a younger person and said they always ran 91 Shell and did drive the car hard. No pic for this one but carbon build up was minimal amount on cly 1 and 2,3,4 was looking clean.

Car 2 was a different story, wan't to say worse case scenario. 40K on engine had a sticking injector, customer did not run 91, ran whatever cheep gas was around. Did not drive the car hard (when I say hard driving I am talking about long rev gear pulls and working the engine getting to full boost) I took pics!!!
Cyl 1 was getting the new injector, Cyl 2 and 3 looked just as bad as 1. For some reason I don't have a pic of cyl4.

So as you can see the direct injection engine still have the same problem as ALL direct injection engines.
I will be removing my manifold coming up this week and depending how the shop is I may make a howto. Because the fuel rail is no longer part of the manifold you don't need new injector seals and it cuts time in about half to remove the manifold. I'm at 35k and have been running E40 mix tuned for 25k miles, oil change every 5k AMSOIL 5w40. Tack days drag strip and long road trips.

See less See more

3

ZPayne

· #52 · Jun 27, 2016

gtimaneg said:
(Ill just copy a post I made on another form)

I have removed a total of two manifolds of the new Gen 3 E888 GTI 2.0T

First vehicle had 15k on it and a stuck open injector. Customer was a younger person and said they always ran 91 Shell and did drive the car hard. No pic for this one but carbon build up was minimal amount on cly 1 and 2,3,4 was looking clean.

Car 2 was a different story, wan't to say worse case scenario. 40K on engine had a sticking injector, customer did not run 91, ran whatever cheep gas was around. Did not drive the car hard (when I say hard driving I am talking about long rev gear pulls and working the engine getting to full boost) I took pics!!!
Cyl 1 was getting the new injector, Cyl 2 and 3 looked just as bad as 1. For some reason I don't have a pic of cyl4.

So as you can see the direct injection engine still have the same problem as ALL direct injection engines.
I will be removing my manifold coming up this week and depending how the shop is I may make a howto. Because the fuel rail is no longer part of the manifold you don't need new injector seals and it cuts time in about half to remove the manifold. I'm at 35k and have been running E40 mix tuned for 25k miles, oil change every 5k AMSOIL 5w40. Tack days drag strip and long road trips.

Wow, thanks for the info!

So in essence, drive it like you stole it?

That's a solution I can get behind

:thumbup:

Sleeveless

· #53 · Jun 27, 2016

gtimaneg said:
(Ill just copy a post I made on another form)

I have removed a total of two manifolds of the new Gen 3 E888 GTI 2.0T

First vehicle had 15k on it and a stuck open injector. Customer was a younger person and said they always ran 91 Shell and did drive the car hard. No pic for this one but carbon build up was minimal amount on cly 1 and 2,3,4 was looking clean.

Car 2 was a different story, wan't to say worse case scenario. 40K on engine had a sticking injector, customer did not run 91, ran whatever cheep gas was around. Did not drive the car hard (when I say hard driving I am talking about long rev gear pulls and working the engine getting to full boost) I took pics!!!
Cyl 1 was getting the new injector, Cyl 2 and 3 looked just as bad as 1. For some reason I don't have a pic of cyl4.

So as you can see the direct injection engine still have the same problem as ALL direct injection engines.
I will be removing my manifold coming up this week and depending how the shop is I may make a howto. Because the fuel rail is no longer part of the manifold you don't need new injector seals and it cuts time in about half to remove the manifold. I'm at 35k and have been running E40 mix tuned for 25k miles, oil change every 5k AMSOIL 5w40. Tack days drag strip and long road trips.

Why do the driving habits matter? It's my understanding that coking with direct injection is due to fuel never passing over the back of the intake valves for cleaning. That should be independent of driving style, or am I misunderstanding?

EPilot

· #54 · Jun 27, 2016

Those pics look like leaking valve stem seals more than anything.

gtimaneg

· #55 · Jun 27, 2016

ZPayne said:
Wow, thanks for the info!

So in essence, drive it like you stole it?

That's a solution I can get behind :thumbup:

In a way lol

Sleeveless said:
Why do the driving habits matter? It's my understanding that coking with direct injection is due to fuel never passing over the back of the intake valves for cleaning. That should be independent of driving style, or am I misunderstanding?

Driving habits matter due to the the design of the intake manifold runners and the divider in the intake port of the head. When you are at low speeds and or light throttle the flap is closed and forcing air to the top half of the port. This helps throttle response, low end torque and your MPG by increasing the intake air velocity into the cylinder. When you are heavy on the throttle, the flaps will open and allow the air to the bottom of the intake port allowing more air flow and more power in the higher rpms.

Because most of the time the carbon builds up on the valve stem not the back of the valve. Is why with carbon build up you get cold start misfires, random misfires at slow speeds (driving around a parking lot). A pic to show the divider installed in the head. And how all the carbon build up is on the valve stem and valve guides.

So if you are always light on the gas, never do long pulls (high RPM driving to open the manifold runners), get the valves moving at high speeds, use cheep gas and cheap oil all this will effect the amount of build up on the valves. Your driving methods has a lot to do with carbon build up.

EPilot said:
Those pics look like leaking valve stem seals more than anything.

Nope, read above and see pic. :thumbup:

See less See more

dmc

· #56 · Jun 28, 2016

Sleeveless said:
Why do the driving habits matter? It's my understanding that coking with direct injection is due to fuel never passing over the back of the intake valves for cleaning. That should be independent of driving style, or am I misunderstanding?

The VWAG patent on DI engines advocates the Italian Tune-Up:

An additional approach for reducing the formation of carbon deposits on the intake valves is to increase the intake valve temperature, at least temporarily, since, surprisingly, it was found that any carbon deposits possibly present are removed at temperatures above 380° C.

To this end, the intake valve unit, which comprises, among other components, the intake valves and the valve stem guide, is designed with means that hinder heat dissipation in such a way that increased surface temperatures of more than 380° C develop at least in the area of the neck of the intake valves in at least one predetermined region of the load characteristic diagram of the internal combustion engine.

At these temperatures, carbon deposits on the intake valves are removed. This region of the characteristic diagram occurs, for example, at speeds over 3,000 rpm, and in that speed range. extends essentially to full load. Even if the internal combustion engine is not operated most of the time in the region during normal driving operation of a motor vehicle, nevertheless, carbon deposits that could adversely affect the operation of the internal combustion engine cannot build up, since their removal in the shaded region of the characteristic diagram occurs very quickly. For example, operation of the internal combustion engine in this region of the characteristic diagram for a period of, for example, 20 min., is sufficient to remove even a thick layer of carbon deposits. In other words, a routine expressway trip cleans the intake valves sufficiently.

3000 rpm or greater for 20 minutes. Of course, this can vary with engine design, but it seems consistent with the idea that running it hard every once in a while will heat the valves sufficiently to remove carbon deposits.

shortybdub

· #57 · Jun 28, 2016

gtimaneg said:
So as you can see the direct injection engine still have the same problem as ALL direct injection engines.
I will be removing my manifold coming up this week and depending how the shop is I may make a howto. Because the fuel rail is no longer part of the manifold you don't need new injector seals and it cuts time in about half to remove the manifold. I'm at 35k and have been running E40 mix tuned for 25k miles, oil change every 5k AMSOIL 5w40. Tack days drag strip and long road trips.

I'm curious what the effectof E40 (or higher mixture) will have on the intake carbonizing. I know that oil vapor through the PCV system has been thought to contribute to the build-up. Since EToH is much cleaner than petroleum fuel, and will vaporize in the venting system, the residual alcohols could possibly lead to some cleaning effect. I know with past oil analysis on the Tiguan, changing to a 45% ethanol mix dropped my nitration (sign of deposit formation) like a rock and my dynamic combustion efficiency went way up. Could be the magic bullet for deposit formation. Love to see pictures of yours when you dive into it.

Akakage

· #58 · Jun 28, 2016

Though dramatic, the evidence presented above at the very least is too small a sample to matter statistically--science counts. That said, I run my Golf TSI 6AT on regular and rarely run it above 2000-2300 rpm, thanks to the tall gearing. If all this contributes to crudded valves, then VW is potentially looking at a huge problem it can't shrug off. But unless/until that proves to be a widespread problem with EA888 Gen3 engines, I'll not worry about it and enjoy my Golf.

GTINC

· #59 · Jun 28, 2016

dmc said:
....3000 rpm or greater for 20 minutes.....

That is any run on the interstate. Why the obsessing if it is the natural way to travel?

JTM65

· #60 · Jun 28, 2016 (Edited)

Is there anyone running water injection? We used to use a mist spray bottle to clean the carbon out of old cars back in the days of mechanical FI and carburetors. I had a buddy years ago that hooked up a very rudimentary water injection system to a TBFI system and it worked very well. It was a GM 305 with over 100k miles and when we did a valve job the combustion chambers and valves were squeaky clean. Supposedly not the norm for that motor with TBFI (I don't know about others, only ever into the one).

41 - 60 of 224 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.