JKnight41

Monday, whenever I went to start up my car, it idled extremely rough. No check engine light, when I drove down my drive, it only got worse so I turned around. By the time I got back to my garage, it had thrown a CEL. I scanned it and got P0304, 4th cylinder misfire.
Here is the list, of what I've done:
- Changed coil pack
-Changed spark plug. (gapped at.030 like I usually do)
-Swapped ignition control modules(need to test them for peace of mind)
- Cleaned and tested injectors. (It's getting fuel)

Im at a loss here, and am stumped. I guess Im going to try and test the Ignition AMPs.

Any help you guys can give me is much appreciated. Thanks in advance.

Peter Badore

Due you have a spare ECU to substitute? Maybe the ECU driver failed for cylinder 4? Did you scan with VCDS or with a generic OBD2 tool?

JKnight41

I don't have a spare ECU. And we just used a tool. My computer with VCDS doesn't work anymore. Thanks for the response!

JKnight41

We did a spark test, and there is no spark in the 4th cylinder. Gonna try the icm, does anybody know what bank the brown clips control? And which one the blacks?

JKnight41

It was an ICM, even though it tested out fine.

Peter Badore

Now you know why Audi calls the ICM a POS and it is not a Power Output Stage.
I have seen many failures of this module and I think its location on the the S4
2.7l biturbo and also the 1.8l turbo AEB A4 is in a location that is too hot. The same module but from a different vendor on an Audi 100 2.8l V6 code AAH rarely fails and in fact the 2.8l V6 AAH module will work in an S4 if you do not mind using only one attaching screw. I have done it using a 163,000 mile original module from a crashed A6.