2.0 TFSI Stutter on WOT

[bergan01]

Hi all,

I am new to this forum, so forgive me if I am posting in the wrong sub.

The car in question is an A4 Allroad 2010 2.0 TFSI. (200k km)
Revo Stage 2 (Running stage 1 setting for the time being)
Test Pipe
R8 Coilpacks (Added after problem started)
Pipercross intake filter

Car has been running fine for 6 months with the current setup.

The problem that I am experiencing is during hard acceleration from about 2k-3K RPM the motor stutter and hesitates hard. After 3K its mostly smooth.
Issue is worse when running up an hill. I would identify the issue as a misfire based on how it feels, but seemingly it is not based on my logs.

Ive had some coils going bad, so first thing I did was switching all the coils to the R8-packs, since I had 4 fresh ones lying around.
That did not do anything to the problem.

Suspected fuel related problem, did a log of Fuel pressure together with misfires. Fuel pressure is stable and no misfires registered.
Have ordered 4 new spark plugs, even though the ones I am currently running are only 10k Km old.

Boost pressure actual vs requested has a diff about 200 hpa = 3 Psi when the stuttering is happening

-Can this be spark plug related even if I get no misfire readings on my logs?
-Suspecting Carbon buildup at the valves?
-Diverter valve issue based on the requested vs actual?

Thanks in advance for any input, or suggestions for log setups.

[Stazi]

Change the plugs or at least check and adjust the gaps. If they are out of spec it will do that regardless of the new coils


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[bergan01]

Thank you for the reply Stazi, I will do that later today.
Will gap them to 0.28".

Is it possible that this would happen due to out of spec plugs, without throwing any errors?

[Slick_B8]

Also, make sure to check/clean your MAF sensor. I had a really bad misfire myself when ever I would floor it and go wot. Happened to me a couple times until i finally cleaned my MAF. Issue went away instantly.

[Stazi]

Try both the above fixes.


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[Iceman502]

Agree with the previous comments. You might want to look for a vacuum leak too. How do your short and long term fuel trims look?

With regards to the different in boost spec vs. actual, how does it behave through the rest of the rev range?

[A4x]

This seems to be a similar concern to the common hesitation on APR software. Many members on this board experience it. I experienced it on both stage 2 and K04 APR software. Hesitation in 3rd gear (ZF8HP) around 3000 rpm. Seems worse when there is more load on the engine (like going up-hill).

See if you can flash back to stock mode and does it change the hesitation?

See if you can swap your intake back to stock and does that change it?

[jfo]

I wouldn't rule out injectors. I chased a problem for months where the engine would stutter badly, at first only when going uphill then later when accelerating. Otherwise it ran smoothly and no codes were set. I changed plugs, coil packs and even engine mounts. Finally it set a misfire code on cylinder three. Changing that injector solved it.

[BennyB8]

I wouldn’t go wot until 3,000 rpm, when the turbo is fully spooled. It’s bad to put load on the engine under 3,000 unless it’s from first gear.


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[bergan01]

I am overwhelmed by the response, thank you all very much.
Have just been out gapping the plugs to 0.28" (More like 0.40 before), and cleaned the MAF. Will do a test run later today.

I did a pull in 3rd gear yesterday with logs of Requested/Actual boost - RPM
You can clearly see where the stutter is happening based on the boost pressure, also my previous statement regarding mismatch between requested and actual is wrong, clearly it meets the requested pressure.

Dont mind the values in the picture, they are representative for the start of the graph only.

Capture1.PNG

Will do a test run, if not successful I will switch to stock map and check how it behaves then.

[Stazi]

Looks like boost surge. Clean the MAF.


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[bergan01]

Looks like boost surge. Clean the MAF.


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Thank you for the reply, I actually did that earlier today, together with regapping the plugs.

Now everything is smooth as before :)

Thank you all for your input!

[Stazi]

Beautiful


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