B7 A4 Stuttering under WOT

[makaheehee]

Hey guys.
I've been noticing some jerking/stuttering when going WOT on my APR Stage 1 tune. I went out and did some Data Logging with the VAGCOM and did all 5 runs APR has on their site - http://www.goapr.com/support/datalogging.php.
I looked through the data to see if I could notice anything strange that would show the jerking, and I found misfires in run 1 and 4, and also wastegate fluctuation in line 27 on run 5.
The first, third, and fourth run seemed to have the most noticeable jerking/stuttering if that means anything.
More fun facts - The car is a 2007 and is sitting at 115k kms right now, The head gasket went before I purchased the car 6 months ago, I recently checked the spark plugs and they all look clean BUT What I did notice is that the top two spark plug wells were ugly looking inside. The uppermost one had a touch of oil sitting ontop of the sparkplug on the side. . Ive done the DV, PCV + Another that I cant remember off the top of my head recalls a few months ago...
I have uploaded all the logs here - http://sdrv.ms/HnU4MG
Any help would be much appreciated!

[PRY4SNO]

Re: B7 A4 Stuttering under WOT

Oil on the plugs = VCG.

Haven't checked your logs but if you have a multimeter you can check out your fuel pump too for the stuttering.

Tested for boost/vac leaks recently?

[Natty54]

Re: B7 A4 Stuttering under WOT

A few common issues with that engine and yes I know you have replaced some:

DV
PCV / Breather Tubes
Coil Packs
Valve Cover can crack
Carbon buildup on valves
HPFP cam follower

[makaheehee]

Re: B7 A4 Stuttering under WOT

Hey, so I forget if the guy replaced the Head Gasket or the Valve Cover gasket =/
But could it be possible that the little bit of oil in there was from when it went the first time and they didnt clean it out very well? Or would it dissipate over time?
But do you mean my HPFP? What should I be looking for if it is intermittent?
Also I have not tested for boost leaks yet, but on the logs it shows fairly smooth boost I believe (This is my first boosted car, so Im not sure how it is supposed to behave in regards to tapering off and such)
@Natty54, Thanks, Ive done some looking around already and have a new cam follower im going to throw in this weekend. Also Im thinking of getting the new Coil Packs. The misfire sum log shows that cylinders 3 and 4 misfired, so should I focus on making those TWO cylinders clean and inspect everything I can with regards to those two? OR should I replace all the coil packsto the same revisions?
Thanks

[BaggedGLI]

Re: B7 A4 Stuttering under WOT

Maybe try taking the coils from 3 and 4 and put them in 1 and 2.

All coils should be the same revision, I've found the old ones tend to die quickly together. (4 coils in 2 weeks)

Give everything a good thorough cleaning though.

[makaheehee]

Re: B7 A4 Stuttering under WOT

Goodcall, will do!
Also any idea on how to properly clean out the inside of the spark plug wells?
Its almost as if there may be some oil burnt onto the side or something? Maybe i'll take a peek at them later tonight and snap a few pictures for reference.
Thanks

[BaggedGLI]

Re: B7 A4 Stuttering under WOT

Leave the sparkplugs in and use some brake clean, spray it down in then stand back and blast it out with compressed air, wear goggles. It shoots everywhere. Repeat as required.

[makaheehee]

Re: B7 A4 Stuttering under WOT

Hmm alright. What if some oil made it down from checking the plugs previously? Is there any way of checking / getting that out? O.o Thanks again.

[Kor]

Re: B7 A4 Stuttering under WOT

My first thought was DV leaking, especially with a tune.

Do you have a boost gauge?

[BaggedGLI]

Re: B7 A4 Stuttering under WOT

Hmm alright. What if some oil made it down from checking the plugs previously? Is there any way of checking / getting that out? O.o Thanks again.

Down where? If you mean in the spark plug holes, see my previous advice. If you mean in the cylinder, then its already too late, its either burnt or through the engine.

[makaheehee]

Re: B7 A4 Stuttering under WOT

@kor I do not have a boost gauge. I was thinking of picking up a vent mounted one though. Hah.
@bagged, alright thanks. I'll see what I can do.

[PRY4SNO]

Re: B7 A4 Stuttering under WOT

Build a DIY boost leak tester and then grab a boost gauge, they're both essential tools (along with a VAGCOM) for any boosted car.

A boost leak test will tell you a lot (where, what, how many). I'd say that's one of the first things you want to do.

[makaheehee]

Re: B7 A4 Stuttering under WOT

Thanks PRY4SNO,
But with the data logs my boost levels are fine.
My airflow numbers are low according to APR. Anyone know why?

[100%VAGitarian]

Re: B7 A4 Stuttering under WOT

Leave the sparkplugs in and use some brake clean, spray it down in then stand back and blast it out with compressed air, wear goggles. It shoots everywhere. Repeat as required.

wrap a rag around your air nozzle. it will absorb the brake clean/oil and then you don't have to worry about it going everywhere

still wear ppe.

[makaheehee]

Re: B7 A4 Stuttering under WOT

100%, Will do. Ill give it a go this weekend. Until then stock tune! We just had some snow after a day of +15'c so it was slippery anyways for the tune.