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Compression test for 2.0t FSI - few questions

78K views 30 replies 13 participants last post by  Butcher  
#1 ·
I am planning on doing a compression check this weekend on my 07 GLI.

My only question is which fuse should I pull? The one for the fuel injectors? or fuel pump?

Also if you could direct me to the location (under hood or side of dash) I can figure it out from there.

I will be using the Craftsman compression test kit if that matters at all.

But if someone has done this before, maybe you can just give me a quick list of what to do just so I dont end up doing anything stupid, just in case :laugh:
 
#2 ·
I used the same kit.It's not that dificult especially if you already have an intake and don't have the OEM filter on.

You have to undo the coil connection and remove the coilpacks.
Then you should remove the spark plugs.
Then you should pull the injector harness clip right below the throttle body.
Then you should screw your tester in each cylinder sequentially, and crank the engine (some say 5 some say 10 times)
You should also unplug your manifold PCV connection to simulate an open throttle.
That's about it.

As for "normal" values, you should look for consistency across the cylinders (not lower than 10%).
Mine did 200 psi on almost all four.

Have fun... :laugh:
 
#3 ·
Don't wanna hack the thread, but I'm just curios on this. About to do my test again(every 20K) with some other routine documenting I do.

But people who view this and have done a compression check on their FSI, post the findings......
-Year:
-Mileage:
-Compression readings 1-4
-Extent of mods
See what these engines are holding up to.......I'll do my test later today along with hopefully getting the car running good.
-J. Hines
 
#5 ·
2006 GLI
120K miles
190-200-190-190

STG II+ with about every bolt-on out there

Also looked in cylinders with a bore-scope...looks awesome still. No carbon on pistons and all cross-hatching still there and good:cool:
-J. Hines
 
#6 ·
no carbon on your pistons???

****, when i changed out my plugs, i looked down there and it looked like someone spilled some ****ing asphalt all over my pistons, mixed with some chocolate cake.

interesting.
 
#10 ·
no carbon on your pistons???

****, when i changed out my plugs, i looked down there and it looked like someone spilled some ****ing asphalt all over my pistons, mixed with some chocolate cake.

interesting.
He said that he has pretty much every bolt on which should include water meth which would eliminate a lot of carbon build up. Also the use of a PCV reroute or catch can would help a lot
 
#8 ·
it's held in a plastic clip that is pushed onto the coolant transfer pipe under intake manifold. Look straight down from where the large vacuum port is on the intake manifold, where the PCV->intake hose goes, right down there. Small D-shaped connector that has 10 or so .5mm wires in it. I'll try to snap a picture tomorrow for you.

And to the clean piston thing.....not sure why. I installed the EuroJet PCV fix when it was first released, then went to the BSH STG. I catchcan, then went "race" VTA when it was released. I have been using SeaFoam every 10K miles through the IAT sensor since 50K and ALWAYS run 93oct. from the same station(Pilot). But not exactly sure why it's so clean, but I'm happy. My goal was to make it to 150-175K miles and then go in and do new rings, rods and pistons to prep for BT build, but may not have to just that soon at this rate:)
-J. Hines
 
#13 ·
PCV to which mani? Exhaust?...since none go to the intake manifold. Or intake?...since none go to the exhaust manifold.
 
#17 ·
Mine tested 1 to 4 @ 191, 195, 192, 192
 
#19 ·
I believe 102psi is minimum limit...and 145psi is the low parameter for "Good". So you likely need to address it between 102 and 145psi.
 
#24 · (Edited)
Where is the the PCV/manifold connection located to simulate a wide open throttle.?:screwy:

I've like to test too.
 
#26 ·
#27 · (Edited)
Is it the green arrow or red arrow that has to be disconnected? :confused:

 
#28 · (Edited)
So I did not disconnect anything, just pulled the fuse 27 out (fuel pump),


06 GLI FSI
145K miles
stock (just BSH air intake)

172,161,160,172

I think it went pretty good for a car with almost 150K miles.
 
#30 ·
Depends on how far you are willing to go with a rebuild. Because yes, it could be just the turbo. Mine had good compression but was losing 1L per 600 miles. I decided to remove the head for rebuilding, with new valve guides and seals, and the combustion chambers of cylinders 3 and 4 were soaked in oil. So the pistons were all removed for new rings and one ring was stuck in the #4 piston. So that piston needed replacing. Went ahead and replaced the rod bearings as well. That rebuild was just 35k miles ago and now mine is smoking a tiny bit when stopped and when it starts to roll from a stop. I hope this time it is just the turbo that has 96k miles on it.

I suggest removing the spark plugs and do the compression test. If any are of the plugs are oily, then you have internal wear. If the compression is good and the plugs appear clean, it may just be the turbo. But if you replace the turbo first, be prepared to go further. This is all assuming the crankcase ventilation is functioning properly. Because if ventilation is obstructed, it may be pushing oil past seals and rings rather than venting.
 
#31 ·
You could have good compression but bad oil rings. Not much you can do to test them but remove the pistons. If the rings are seized to the piston, that will cause the rign not to do their job. Even when the rings on sitting on the bench, unless they are broken, you usually cannot see with your eyes what is wrong with them.

Oil consumption can be a real chore to locate the cause.