I've already looked at plenty of forums and threads about this. I have a 2004 ultrasport b6 with the 3.0 engine. When I got the car 2 months ago, there was a misfire code in all 6 cylinders. I was told by the guy I got it from that it probably just needed spark plugs and coil packs so I changed all of the coil packs and spark plugs and 3 of the codes went away. I took it to my local mechanic that had a few A4's and he did a compression test and it had low compression in 3 cylinders. So he replaced the engine for me with an engine with 56k miles, new timing belt, water pump, fuel filter, air filter, intake manifold gasket. New motor has good compression. But I still have misfire codes in cylinder 1,2,3. The car isn't actually misfiring though.Runs good and idles good. The cel isnt flashing. He looked for vacuum leaks, oil leaks, said the injectors were good. So i'm kinda lost here. I was thinking maybe the coil pack harness or ecu?

 

The old codes were cleared, right? It will be kind of hard to track down misfires that don't exist. I'd clear codes again, clean all the ignition and injector connectors, then run it some more. VAG-COM has a misfire counter for each cylinder that you can watch, in case the misfires are too weak to feel.

 

yes the codes were cleared. and the check engine light isn't flashing. and you can't feel any misfire. and okay thanks ill try that out. I was hoping after replacing the engine, brand new coil packs, and spark plugs the issue would go away. I dumped so much money into the car already.