2003 pt cruiser. ok so it started with replacing the alternator, then after getting it all back together, it had a misfire on cylinder 1, checked the plug looked like crap, replaced it to see if that would fix it, it didn't. replaced all 4 plugs, wires and coil, same problem. replaced a second coil, same problem. swapped out the computer and you guessed it same problem. no codes present on either computer, I'm at a standstill and don't know what to do next. any insight would be helpful.

 

update. so, I've discovered that I'm not getting spark though the 1-4 coil. best I can figure is that there's an issue with the harness. going to follow the wires back as far as I can to see if something is shorted to ground. but by what I can tell it all goes into the pcm, but I already tried swapping that out and no dice.

 

ok so last 2 updates didn't post for whatever reason, but anyway, big update. after trying the whole 9 yards of things, from replacing the crank sensor, swapping out coils and better plugs. I was finally able to get it to start. however, it was only running on 2 cylinders. (2&3) no spark on 1&4. swapped out the pcm again and after some cranking, it fired up for about a minute then died. upon research I have discovered that the junkyard computer needs the corresponding skim module and key and lock cylinder from the same doner car. hopefully the junkyard i got it from hasn't crushed it yet. the skim module is located with the lock cylinder, they actually work in conjunction. it's like a little computer that has a loop around the key. hope this helps everyone else. hopefully I can save myself the hassle of have the pcm reprogrammed.

 

why not just get the PCM vin flashed?
the other way the VIN won't match the car, the mileage will be wrong, you'll need to swap a whole bunch of parts, and you'll need new keys cut.

 

update: so, it was indeed the pcm, put in another pcm from a car that either didn't come with the skim function, or it was already re-flashed. took my skim module out to be safe. starts up after some cranking, its having trouble relearning the new crank sensor. so, it keeps throwing the codes for that. not sure why it's taking so long for the crank sensor to re-learn, I've been driving it for a few weeks and have been clearing the codes regularly.

 

What codes are being set?

There is no 'learning' the new crank sensor. If the new crank sensor is not OE/Mopar, it may be part of the problem. I have had auto parts store varieties fail out of the box multiple times. Suggest only using OE/mopar sensors only.

Are the new plugs the copper Champion RE16MC gapped at 0.040 inches? These engines are known to not run well on platinum/iridium plugs.