99SH

Have a MY06 w/96k miles; motor is stock. I just replaced my clutch with an Exedy replacement & AP1 flywheel a few weeks ago. Ever since then, I've been getting a misfire CEL on Cyl #3.

The car runs perfectly fine. No rough idle, nothing. The misfire comes on ~10 seconds after I start the car. Almost seems like it's a false misfire.

I read the misfire thread and thought I should change my knock sensor first. It was slightly loose and thought I may have damaged it. Changed it, but the code still remains. Swapped plugs & coils with an adjacent cylinder, no cigar. Did a compression test and measured >210 across all cylinders. Cyl #3 was the lowest out of the group, but 210 is pretty healthy.

Now I've narrowed it down to valve adjustment or injectors (more likely). Just seems really odd that this was triggered only after the clutch job. My next step is to do a valve adjustment; it's been 25k miles since my last one. If that doesn't do it, it must be a bad injector.

Thoughts?

T-Smac

Anything that slows a crank will read as a misfire. A clutch could certainly do that, but I would assume it would be a random misfire. I'd go after injectors or valve adj. before that.

99SH

Since the CEL light appears w/the tranny in neutral at idle, I think the clutch can be exonerated.

99SH

I was reading thru the HELMs manual and learned something new. There is a CKP relearn procedure which could be performed so that the ECM can relearn the crank pattern. Since I'm getting a false misfire (or seems like), this may do the trick. I did install a lighter AP1 flywheel, maybe it was enough to throw the system off? Although the delta weight savings is minimal compared to the AP2 flywheel, this doesn't make 100% sense. I also would think it would throw a random misfire, as opposed to Cyl 3 always.

I have 3 items left before I reach a dead end. Valve adj, injectors and CKP relearn.

99SH

Just to update this thread in case anyone else experiences a similar issue.

I swapped injectors between Cyl 3 & 4; however the misfire repeated on Cyl 3.

Just finished a valve adjustment, and it seems to have gone away now. There are no pending misfire codes!