i recently bought an a4 1.8se and have a problem .when ideling the revs will bounce between 400-900 rpms this only lasts for a few seconds after decelaration. then they levelout at around 900 no warning lights are showing and engine is fine when in motion i have recently put some injection cleaner into the petrol tank but theres no change any assistance wouid be very much appreciated thanx in advance

 

I know exaclty what it is.
My 97 did exactly the same thing.

Your Throttle Body is very dirty. Get some carb cleaner, clean it out good with a toothbrush, and enjoy your nice new non-bouncing idle.

 

Do you mean like cleaning where the butterfly valve is or where like the computer part is?

 

Yes, behind the butterfly valve on the throttle body intake.
Just remove the hose from the intercooler, clean with toothbrush (make sure not to set it by the bathroom sink when you are done), spray, clean, spray, clean, spray. clean, until no more dirt running out when you spray in there.
Put a rag under the TB to catch the runoff. Re-attach hose.Good to go. A 5 minute job that will make your intake happy.

After seeing how dirty mine was the first time, now every time I change the oil (5k) I clean and oil my air filter, clean the TB, and rotate the tires.

 

thanks for the advice but do you perform the clean out with the tb on the car or take it off secondly i have read that after you clean the tb it has to be realighned can this be done without vag-com ps if it can be cleaned on the car you say spray cleaner into the tb but my tb is angled upwards so the cleaner wouid run into the tb is this okay or shouid i take it of thanx again

 

I don't know what year model your car is but I believe that you can do a TB adjustment without a vag-com. Just turn thekey to accessorywithout starting it and see if you can hear the little beeping noise from under the hood. If so, the noise will last for about 30-45 second which indicate the TB is being adjusted. I haven't clean my TB so can't help you there but let me know how it is done and if that resolve your problem.

 

sorry my car is a 1996 1.8se can the tb on this car be set the way described as above