02 grand prix misfire

[threewest]

i have a 02 grand prix 3.1L...car is stock with about 75,000 miles....im getting a p0301 engine misfires...about a month ago i had this problem..i changed the plugs and wires and it went away for a few days..now its back ive since ohm out the injectors which were in spec and also cleaned them..i ohm out the wiring from the injector to the harness that was fine..then i ohm out the coil packs and that checked out fine..now im kinda stuck and dont where to go from here...this is my first post and any info will help..thanks for your time

[richtazz]

P0301 is specific to cylinder #1. A random misfire would be P0300. Try swapping the spark plug and wire from another cylinder first to see if the misfire moves with them (swap 1 and 3, as the wires are about the same length and they're right next to one another). If not, then you most likely have a bad injector (injectors passing an ohm test doesn't necessarily mean they're good). The last thing to check is compression on that cylinder.

[threewest]

update..i pulled the codes today..i have a p0301 cylinder 1 misfire...p0201 injector 1 electrical circuit...p0742 torque converter clutch stuck on...i figure the p0201 is causing the p0301 code..dont know where to start on the p0742..any info will help...thanks

[BNaylor]

Welcome to AF.

DTC P0201 means there is a fuel injector circuit fault to include an open or short which means it could be the injector, electrical connector to the fuel injector, the PCM module or wiring from PCM to the injector. I know it is hard to do on a 3100 engine but check for an injector pulse signal (flashing). You can check it at that main fuel injector wiring harness connector.

For the P0742 TCC DTC when was the last time the tranny was serviced? Pan drop with ATF (Dextron-III) and screen filter?

[threewest]

could it be checked with a 12v test light and back probe the harness...

[BNaylor]

Originally Posted by threewest

could it be checked with a 12v test light and back probe the harness...

Yes, that is what I use since you have to pull the upper intake manifold to connect a noid light. Just find the right color coded wire for the pulse (toggles lo/hi). One side of the injector will always have 12 volts at ignition ON. Good luck.

[threewest]

i just checked the ground side of injector 1 and i had nothing so im gonna ohm out from the injector 1 to the pcm to see if there is an open..if there is no open then injector driver in the pcm is probably burnt out...thanks again for info....