well i just got my car back from the shop. they left it outside for sometime and when i went to start it it fired right up but real low idle speed and then died. only way i could get it to fire and stay running was to throttle it but as i drove it it got better but still idles rough, bounces between 900-1000rpm. this is in 30 degree weather of WY, also a 99 1.8T quatro with 89000.

 

Do you know if the battery went dead or disconnected?

If that was the case usally you have to hook the car to VAG software and sweep in the throttlebody otherwise the car will not know the throttleblade position and will run erratic.

 

the battery probably was disconnected since the shop-dealer put in a fuel sending unit, they also repaired the driver seat and it also has the airbag light on since they fixed it. they told me that they didnt have the tools to turn the light off but they would cover the charge for another shop that could.

 

To fix the throttle body issue (if that is the problem) disconnect the battery again for maybe a half hour, then reconnect it. Turn the key on to full electrical power (but don't start the engine) and you'll hear a humming noise from the engine - that's the throttle body aligning itself. Once it stops humming, you're good to go - start it up and see if it stabilizes your idle.

 

i just tried unhooking the battery and i heard it reset the throttle but its still real rough. i got my rpms mixed up, in nuetral or park bounces tween almost 1k and 750. in gear its around 500-750 sometimes if it doesnt try to stall. i even took it for a short drive and no change in idle speeds, but the engine performs great.

 

Coolant temp sensor might be going, otherwise might be the throttle body itself

 

i just put in a coolant temp sensor. this thing has got me pullin my hair out! im going to get back with the dealer 2morow cuz it didnt idle this rough before they had it. i havent even had it for a month now and its been more of a headache than any car ive had. but thanks for all your guys suggestions and info!

 

i had this same problem..i replaced the power steering pump and it fixed beleive it or not

 

2002 a4, especially when cold, car vibrates a little @900rpm when in Drive - it is very stable. I use 91 octane gas.
WIll have it checked out next week

 

Hi everyone I have a 98 2.8 a4 quattro, it is like 30 degree here and I recently unhooked my battery like for 10 min and when i hooked it back up the idle got ruff and when I am driving I take it out of gear the car some times even dies. Any help will be appreciated.