I took my truck wheelin alittle over a month ago, and it's STILL not fixed... After a complete Tune up, Trans flush, and new sensors, The check engine light won't go off.. It kept throwing "random Misfire" codes... The Cyl. #'s changed, and no one could figure out what it was... I came across a '99 motor, and with 225K on my motor, I decided to put it in. The problem still didn't go away. I put a new ECU in, and now, the O/D light is on and won't go off.. It goes into O/D, but the light is still on. Please, someone give me an idea of what i'm looking at here, because no one seems to know..

 

did you onnect the wiring harness correctly? There are 4 connectors that go to the tranny. Maybe one of them was put in upside down (it is theround one that is right by the kickdown cable bracket). I was looking at it and it can still be plugged in upside down.

I am replacing my harness and it can be a tough SOB to do. Lots of troubleshooting.

 

Also check your tranny temp connector. if it reads too hot then the OD light will go on. At least my od light went on when my tranny temp would get high due to a bad converter.

 

Have you checked your catalytic converter? I remember reading someone on this forum say that if the cat is clogged, it will cause cylinder msifires.

 

+1 if its clogged completely it will cause too much backpressure and set the engine haywire.

 

Well, I'll have to check the connections, but I put a new cat on it, and thats kind of what set this whole thing in motion.. First the cat, then lockup solenoid.. then everything else.. I have it at a trans shop now looking at the solenoid pack.. Word on the street is that they go bad in chrysler motors... Anyone have any other suggestions while i'm having it looked at?

 

Weak fuel pump, weak coil, plugged injectors bad crank sensorcould cause the random misfire.
I'm assuming all these were swapped from the old engine.
"new" engine could have a blown Plenum gasket too. You take your chances with used parts.
Trans solenoids are not commonly failed parts on these trannys but anything is possible.