My wife's A4 has had this rough idle problem for a couple of years now. Basically, at a stop light, the idle will go from 700-1200 rpm's and not settle down unless it is warm enough outside. If I put the car in neutral, that reduces, but does not eliminate the problem. A few years back, we went to the dealer who cleaned the throttle body and took pleasure in telling us it was not covered under the alleged bumper to bumper warranty. Anyone else had this problem? I hear it also occurs with TTs. Am planning on selling this car soon so would like to get a fix (and hopefully not blow $250 like the last time).

Thanks

 

Check for a vacuum leak. Praticularly in the hose that comes from the intake near the front of the motor.

 

Some times when you lose power to the Engine Control Module (ECM) by either disconnecting the battery, or having the battery run dead for some reason, the throttle valve control module must be re-adapted. This will cause lack of power and/or poor idle concerns. There are two ways to correct this. One is to take it to the dealership, and have it adapted. Or two just swithch the ignition on ( engine not running ) and let it sit for ten seconds to allow the ECM to run a self test to readapt the throttle valve control module. so give it a shot and see if it helps. Good luck and let me know how it goes.