Thread: Misfire help

Okay GPF, I have a problem. My '01 GTP has recently developed a misfire in Cylinder 1. Car has some mods including 3.5 pulley, 10mm wires, TR6 plugs, etc. I bought the 10mm plugs and installed them, it was fine for a few days then started misfiring. So I replaced the coil as they are original with 180k miles on em. Still misfiring. Now replaced plugs with new TR6, all gaped correctly. Still misfiring. I tested the 10mm and found its not the wire.

It only misfires under heavy throttle above 4lbs of boost, sound like it could be a lean misfire caused by injector?

Put your stock coils back in unless you want more misfires down the road. I'd try and clean your injectors. Also still don't rule out the possibilty of those wires. I'd buy some cheapo ones temporarily, or if you still have your stock ones and try it. Lots of people have issues with aftermarket wires.

He never said he changed coil brands, just that he tried a new one. So that rules that out as a possible cause, swapping back to the one he took off will do nothing.

He tested the wires and has new plugs, so that's not a problem.

Last on the list is the ICM itself, I'd swap it with another ICM from another car to test it out. But that's only if you have another 3800 car handy for an hour.

Yea the coil is just a OE replacement one. The original one was shot for sure. I have heard people have problems with wires that's why I tested them. Determined the wires are okay. The injectors are original and that's why I want to see about them next. I have kinda ruled out ICM because its not random misfires on all cylinders as if ICM was toast. It's just cylinder 1 and always has been this whole time

The ICM can be just 1 cylinder, do not rule that out.

Are ICMs the same across GTPs and GTs? I guess I'm off to the junkyard lmao

Originally Posted by Dadkota

Are ICMs the same across GTPs and GTs? I guess I'm off to the junkyard lmao

Yes.

Cool I'll give it a go, thanks

Flip two injectors, see if the problem follows the suspect injector.


Not sure how you tested the spark plug wires, but I'd flip a couple of those as well. Sometimes the resistance is fine, but they don't sit right on the plug/coil.

Thanks for the injector tip! I tested resistance and also swapped for stock wires and still had the misfire