sssuperlite23

hoping someone has seen this before. 2000 a6 2.8 engine stalls or at least stumbles when not moving. starts up again no problem. but then stalls again if in gear and not kept at higher idle. still stumbles though. when I get moving again it runs fine. I replaced crank sensor and both bank two o2 sensors. just discovered it likes life much better with hood open. so obviously something is temperature sensitive. is there a temp sensor that could be the culprit? if so where would it be located? any ideas would be greatly appreciated.

tester123

Check for any obvious obstructions? Does it happen after engine warmed up or even on a cold start... Try to establish/confirm the conditions when this happens. Otherwise, you could be shooting in dark. Do you have VAG-COM? Check for codes? Try pouring a bottle or 3 of "dry gas" (maybe moisture in gas tank?)... It could be timing or any few other things... too vague for a solution.

sssuperlite23

runs fine when for a few minutes at cold start. im in the Chicago area. was a little warm for a couple days not long ago and seemed to be worse. it runs fine when moving or when you stop and go again before sitting more than lets say 45 seconds. I don't think its a timing issue. no vag-com.

sssuperlite23

sorry no codes with scanner

tester123

How many miles? when was the last maintenance? Like I said, it could be bad gas/moisture, a Vacuum leak etc. If maintenance and gas check out ok, then start digging for a vacuum leak.

sssuperlite23

150,000. maintenance up to date. been through a couple tanks of fuel since this first started. already looked for vacuum leak and found nothing. most hoses replaced a couple years ago just in case when doing secondary air. anybody know about any air temp sensor in engine bay? otherwise it may be time to buy a vag-com. or god forbid pay a pro mechanic. I pride myself on never doing that.

tester123

Then VAG-COM it is.

sssuperlite23

I thought I would post results in case anyone else ever runs into this. I started applying heat with a hairdryer to MAF sensor. Bingo, that reproduced stumble. I disconnected MAF sensor and closed hood. No stumble. New sensor arrives today. Thanks for your guidance Tester123.

tester123

Excellent! By the way, it is great that a new member like yourself came back and posted the results. That's the only way other people can find solutions. Good Job!

I remember looking all over for that "air-temp" sensor when troubleshooting MAF. Buried in the manual, it indicated that on my car it is integrated into MAF. So, even if the Air-Flow measurement portion(hot wire) works, if the air-temp sensor is gone, it is useless.

With VAG-COM, this would've saved you time as it easy to monitor air-temp / air flow groups.

I am glad you found the problem so quickly! If you read the link for "fuel banks lean" in my signature, you'd realize that this bugged me for over 2 years (provided I didn't REALLY put much effort except towards the end where I got fed up and finally found the problem). MAF problems can be tricky!

johnkk

Your diagnosis already helped. Replaced an ignition module and the problem came back only after the car was completely warmed up. Unplugging the MAF stopped the misfire.

thanks very much