Thread: Misfire Issue

2002 Grand Prix GTP

So not to long ago couple months or so i had a coil go down on #2 cylinder. So i replaced plugs wires and that coil. Ran just fine til just shy of a week ago. I did a fuel system cleaning on it a 3 step service. That night on the way home it ran great til I got off the highway and it chugged real bad at idle but no code. The next morning on my way to work doing 65 or so it threw cel P0202 cylinder 2 misfire. Took it to my mechanic and we switched coils and still misfire on 2. So i left it with him and he replaced the ignition control module and it did ok all the way home. This morning it was a bad misfire on 2 and i also got P0302 for cylinder 2. So I hope it's just the injector got clogged or its the pcm because i hear it could be bad. Any and all advice is appreciated. Thanks in advance

Switch injector off two with one see if the mis follows the injector

Im pretty sure my mechanic is doing that its his bday today tho so i can't bug him to much

Get it all squared away?

Well kinda i hope. It wasnt the injector but replaced it anyway. He is 95% sure it's the pcm we will find out today

Turns out it was the PCM. Gotta love chasing codes right back to the source that gave us the code. Crazy how that works but she's alive and well again

Oh yea it was so much fun. The lesson learned is to not do fuel system cleanings on 3800 SC with 140k it will fry the PCM lol. I know that is not what made it go bad it was just a crazy coincidence

His laws i tell ya. Im just mad because i did the fuel system cleaning and then had the issue and replaced the injectors chasings Murphys tail