What the deal here? I just put in a new battery and this issue just started. The car is a 1997 a4 quattro. When im driving and put on the brakes the rpm's will drop to like 300-400 after becoming stationary. It vibrates for a second and the rpm's go back up to a normal range.

It sounds like a grounding issue but i might be totally off. Could you guys lend me some advice?

 

I would try doing a TBA, turn the key on and dont start it for 3 minutes or so.

 

What is a TBA?

 

Im not sure what the TBA is. I tried to search for it with no results.

Am I experiencing a common issue?

 

Throttle Body Adjustment. When you do what he was saying, it allows the throttle body to align itself via the ECU's command. This often helps stabilize the running of the car.

 

Same thing happened to me. I took my car in to the audi dealership to have my ignition switch fixed. When they did the repair they had to disconnect the battery. When I picked the car up... it was doing what yours was doing, except it rarely stayed running.... normally it would die.

The shop should have re-configured the ecu after they hooked the battery back up but didnt. Your car will automatically re-configure it after it is driven for a bit. The audi dealership told me 50 miles. Sure enough, about 40 - 50 miles later it was fine.

 

Must be nice that yours corrects that quickly. Every time I've had my battery disconnected, I do a TBA afterward and it still takes a week before it's back to normal. To my knowledge, my car is the only one that does take that long - no one else that I know needs nearly as much relearn time.

 

Yeah i see an immediate difference after I do one, although even if I dont do one it isnt too serious (it never gets close to dieing, it just wavers).

 

my car had the same problem, only the other way around. after stopping at a light the RPM's would go up to 1100-1200 for a second or so, then drop back to normal. a TBA did the trick.

 

ok so i left the key in the on position for about 5 minutes. Its still doing it so no results yet. I hope that it starts behaving normally again. Could this possible be another issue?