What?? An S4 with a misfire?

[SRSslpr]

As the title states, yes I am having a misfire. Yes, I have done my research as far as searching and finding out what the usual causes are. I have checked for boost leaks, I have swapped coil packs, I have changed spark plugs, I have checked my o2 sensors, I have checked my EGT sensors. The problem is that I am consistently getting a misfire on cylinder 6 only under load. If I ease into the throttle I can drive it find and it doesn't seem to misfire unless I am on it for awhile. My next step will be to swap the fuel injectors to see if that is causing the misfire. I'm curious as to what else may be causing this? I don't think it would be the ICM because it is staying on one cylinder. Any and all help with this would be greatly appreciated. Thanks!

[RolledMySTi]

Have you swapped ICM's?

[P0234]

So since you did your research, I'm sure you already moved the #6 fuel injector and that didn't do anything so then you did a compression test, and that came back fine....

[Angular]

I had a nasty misfire problem for a while. In the beginning it was only when at 1/2 to full throttle, but then it got progressively worse to where it was missing all the time. I bought an ICM and a coil pack and took everything apart, measured the resistance of both ICMs and the coil packs, THOUGHT maybe I'd identified the culprit but I was mistaken. The misfire persisted. Spark plugs looked fine but finally for good measure I replaced them and magically the misfire went away.

YMMV, of course. I would recommend replacing the plug(s), and swapping the coil pack and injector (one at a time) to see if the problem moves to another cylinder with the offending component.

[SRSslpr]

Thanks for the advice....after tearing apart the fuel line and switching out the fuel injectors with no improvement; My friend came over with a VAG and we logged some real time data and found that the car was only misfiring on cylinder 5 now. So, after remembering that I had switched the coil pack from cylinder 6 to cylinder 5 a light bulb came on. I swapped out the coil pack with an extra one I had and the misfire magically went away. Not sure why initially when we pulled the codes the misfire stayed on 6 even after changing the coilpacks, but all in all in the misfire is gone. I just wish that the ecu would just throw a code saying look here stupid.