I went to lunch during work today, and the car ran fine. Left the restaurant and the engine started skipping, shaking, etc.
I stopped by a parts dealer, and had them use their computer and it was showing p0304. (misfire on cylinder 4)
From everything I have read on here, it's the ignition coil on cylinder 4. (front, driver's side cylinder)

I've done a LOT of searching, now for a totally ignorant question...

Are these ignition coils over the plugs or are they separate, and somewhere else in the engine compartment??

I have a replacement coming tomorrow morning, and plan on replacing it immediately.

It's a 2001 Allroad as previously mentioned.

I recently purchased it. It's got 124,000 miles, but was very well cared for. I have the p0421 code (bank 1 cat) code, but I have had Audi look at it, and they say the cat and sensor are fine, just too sensitive. Love the car, and feel it's already spoiled me.

Anyway, if someone could point me in the right direction to find the coil, I'd much appreciate it!

 

It's a coil-on-plug design. The three squares with harness connections on each valve cover are the coil bases. Just unplug, pull off, and replace.

A guy local to me also had the cat code issue on his 30v Passat. The dealer said the same thing to him, that the tolerances were ridiculously tight. For $100 they reflashed his computer with wider tolerance settings for the rear O2s and his problem went away. You could look into that.

 

Thanks for the info.
I dropped the new Coil in this morning, and still having the same problem.
So, I switched plugs on the Ignition Control Module on top of the airbox, and started it up again. Same problem, but shudder seemed different. could not get the car to CEL on me, but did notice a horrible eggs smell from exhaust and raw gas. I'm guessing the true problem is one of the ICMs?
Switched it back the original way, and went back to doing what it was doing before.

Checked all my connections, and everything else seemed in order.

Again, thanks for your thoughts.

 

I had this same problem. it turned out to be the one of the ignition control modules were bad just buy one and switch it out until you find which one is bad and your problem should go away. I see you said you swapped plugs but not the modules. like I said buy one and switch either one out until the car runs fine.

 

I finally took it back to the dealer.

They sent it out, and it had a bad coil on cylinder 1, a bad set of plugs and one of the ignition modules were bad!

Worst of all the dealer had the gall to stick me with the $600 bill! I bought the car less than 2 months ago, and they are still trying to say they had it tuned up before selling it to me.

Thanks for the responses!

 

Im gonna be honest with you there was nothing wrong with the plugs or ignition coil it was the module like I said. they must have just started troubleshooting on your tab by starting with plugs then swapping a new coil (all on your tab of course) O well wish I would have caught u sooner (maybe next time eh?)