CMK

This could be any number of things, right? Lack of air or fuel...

It only really happens if the car's been sitting for a little while (overnight). Nearest Audi dealer is booked for two weeks...anything I can check myself? How do I get to the airbox?

Dr. Gräfenberg

This could be due to condensation... It may help.

CMK

Thanks a lot! I'll check out the local shop.

Ray Calvo

When gas tank is near empty, dump in the Techron then fill the tank with 93 octane fuel. Then go for about a 150+mile trip on an interstate or flog it on a back road. If it's due to carbon buildup, ths should help.

CMK

Very interesting...I'll try both. But maybe not at the same time?

Kris Hansen

you need to get it hot...

Kris Hansen

If it only happens after a long sit, do you get any smoke when it does start?

TonyG3

check plug wires

audi49

There's something about these A4's that cause them to stumble at start-up after a prior short running period of the car. For example, if I pull my car out of the garage to wash it (car runs for 20 seconds) and then I restart it later to put back into the garage, the car tends to run rough until i accelerate out of the driveway. it's quite predictable for me and I've heard others have the same 'problem'.

Tom

Kinetic0510

it eventually stopped doing it on it's own. I finally narrowed it down to the gasoline brand I had in my car at the time. It only seemed to do it with Texaco or Conoco gasoline. Never did it with my typical Amoco (BP) or Phillips 66 (#1 choice).