What should I look at next?
I have a p0301. Have changed the spark plugs and rotated coils to rule them out. on 2009 Pontiac G6
5 answers 2 comments
Check for vacuum leak and injector pulse. Plug wet when removed? If so, check compression. Seems we have quite a following here, hope you get it fixed!
I'd start looking at the injector or injector wire harness
Boy i sure wish i had thought of THAT!!! Do you know what injector pulse is?
When does the misfire occur? At idle? Under a load? Or all of the time? Is it constant or does it come and go?
Try the intake induction service, Per GM Bulletin.
Just rotating the coils will not show up a miss fire, as it will just move to another cylinder. Try disconnecting one coil at a time when engine is running. If when a certain coil is disconnect there is no difference in engine missing, you have found a bad coil.
It will change the misfire code if coil is defective and switched to another cylinder!