Hey guys lookin for help on my car.

its a 2004 Ion Redline. I put a new engine in and have had problems ever since. It keeps having a misfire with cyl 4. I have swapped the coils, put in new spark pluigs, and swapped injectors to no avail.

the last time it was at the dealer he said he found a pinched wire on the ignition coil harness and repaired it. That took care of the problem for close to a month (it would still happen intermittantly though) but now its misfiring again all the time. Its at the dealer right now but im wondering if anyone has any ideas what it could be from?

The car is bone stock except I deleted the catalytic converter (because the dealer thought it was plugged and it wasnt). Could there be a loose ground or something somewhere from when I did the engine swap? I couldnt see it only causing a dead mis on cyl 4 only though.

The tech also installed a new throttle body for me from a 2006 Redline/Cobalt. Could the throttle body have any bearing on the number four cylinder?


There are no other sensor codes coming up, just the cyl 4 misfire code.

Any help is appreciated this car is driving me crazy and Im leaving for a trip this Thursday thats 300 miles round trip




Also compression is 180 across the board.

 

From your description, I had almost the exact same issue about a month ago. It was a wire that had rubbed through (part of the #4 coil circuit). If I were you I would double and triple check that harness.

 

Thanks for the reply. The tech at the dealer said he tried swapping in his computer (he has the same car) and said that seems to have fixed it but hes still test driving to make sure.

Just doesnt seem likely that my stock computer with only 84k miles would go bad?

 

I did a PCM swap too and that SEEMED to fix it. 40 miles later it started exhibiting the same symptoms. Have him make sure the car is driven around a good amount before deciding its definitely the PCM.

 

I got a used PCM from the tech at the dealer for $75 so ill drive the car home tonight and see if that solves it. Its a 33 miles drive home from the dealer and then 30 miles tomorrow each way to work so i should know by tomorrow whether it fixes it.

I'm thinking its good because before the PCM swap the car had a misfire right on startup and it never stopped. After the PCM swap it went away on the first startup. He said thats also why its been intermittent and hard to diagnose. Thanks for the repsonse and heads up.

regards,