A3 2.0Tfsi (BWA) stuttering when engine cold.

[Sharkie1976]

Hey guys.
Every day after work I drive home and at the same stretch of road I get an issue. When slowly accelerating to join the motorway, the engine stutters from 3rd gear through to 5th at approx 2000rpm. Then I come off the motorway to join the next one, and the engine is warming up and getting close to the standard 90 deg. Once it gets to 90 deg it seems the issue isnt there anymore. So this only seems to happen when engine is at a cold temperature. On the way to work I take the back roads and the issue isn’t as apparent.
I had a service/repair 6 weeks ago, oil, filter and rear abs sensor and hub, front outer cv gaiter.
I didn’t have this problem before the service/repair and it wasn’t apparent for a couple of weeks after. The only other thing that I remember was running the fuel down to about 20 miles in the tank before filling up. Coincidence? I don’t know.
Plugs and coils newly fitted last week, same problem. So I’ve ruled those out already.
Any ideas?
Thanks in advance.!!

 

[davidws]

Mine does something similar, albeit only in really cold weather and in 2nd gear. Brought it to Audi 2 weeks ago and they suggested it could be a dirty throttle body (and quoted £460 to take it out, clean it, put it back in)

 

[Retroman]

To me it hints at a weakened fuel air mixture, which would be more noticeable on a cold start or cold engine. I would expect something like a small vacuum leak or failing MAF sensor. When they did the service it is possible that pipework around the air filter box was loosened and sometimes the jubilee clips holding the MAF sensor in place get removed/replaced so many times that the thread wears and they fail to tighten properly.

 

[Sharkie1976]

Mine does something similar, albeit only in really cold weather and in 2nd gear. Brought it to Audi 2 weeks ago and they suggested it could be a dirty throttle body (and quoted £460 to take it out, clean it, put it back in)

Hey mate. Thx for reply.
I cleaned the throttle body last year (which wasn’t dirty at all tbh). I will bear this in mind tho, so thanks for your input sir. Appreciated

 

[Sharkie1976]

To me it hints at a weakened fuel air mixture, which would be more noticeable on a cold start or cold engine. I would expect something like a small vacuum leak or failing MAF sensor. When they did the service it is possible that pipework around the air filter box was loosened and sometimes the jubilee clips holding the MAF sensor in place get removed/replaced so many times that the thread wears and they fail to tighten properly.

Hi Retroman.
The cover is fine, and so are the clips to the maf housing, the garage didn’t do plugs and coils, I did them myself, and I’m always triple checking my work. I know I have a very small air leak in the turbo hose, but that had been there for quite sometime, and never caused an issue with how the car runs. Not ruling out an air leak tho. You also mention maf sensor, and I did clean the wire etc a couple of nights ago, and yesterday for the first time in a couple of weeks (and typically when I was doing some live logging on VCDS), it didn’t stutter once. It was a warmer day, so need to go for a drive again today to check again. Could quite possibly be maf related. It didn’t look dirty however but gave it a few squirts anyway.
Thx for your reply, appreciated. I’ll let u know when I’ve tested it again.
Cheer mate.

 

[Sharkie1976]

Ok, so I drove home from work today and the weather is a bit cooler than last time. The engine didn’t judder as bad as last couple of weeks, but did do it very slightly just a few times. Do you think it could be the Maf on its way out.? My readings for STFT at idle fluctuate around 1%, and LTFT stays stubborn at -7.5% (running slightly rich) and stays at -7.5% regardless of increasing the RPM in stages up to 3500rpm. I know that an excessive figure of +-10% is within spec, but didn’t know if it should be stuck on the -7.5% reading???
Any other tests I can do??