P0301 Code (Misfire with new Engine)
 

I had a new GM Crate engine installed with a new transmission on my 2002 SS. Does anyone have a clue as why I am still receiving a P0301 misfire code with my check engine light. It has been three months of trial and error. Still no answers.

Here's what all I've had done so far...
-replaced coil packs
-replaced fuel injectors
-replaced spark plugs and wires

The factory book doesn't list DTC P0301. Did you mean P0300? If you did, since the engine was replaced, you will probably need to go through the "Crankshaft Position Variation Learn Procedure" (CKP System Variation Learn Procedure). This requires a scan tool and probably has to be a GM Tech II which has a setting for crankshaft variation learn. The PCM stores crankshaft variation in it's memory and that needs to relearned for the new engine. If you went through that procedure, it could be the ICM.

Went online and found that P0301 is misfire on cylinder #1. P0300 is multiple cylinder misfire. The CK system variation learn procedure needs to done any time the engine is changed, and you will need a GM Tech II to do that, so if it wasn't you'll need to. If you don't soon it will damage the cat. If you still have a problem, I would concentrate on the ICM.

Check the wiring circuit for cylinder #1. Make sure to trace the wiring all the way back to the PCM. If the wiring checks out you may have a bad O2 sensor. Worst scenario could be a bad PCM or a burnt valve. A bad cat converter can also cause a misfire, but it is rare.

Thanks for the input guys! I'll apply what I've learned here to hopefully get results soon!

Well, I'm waiting on the new PCM to arrive. Wiring tested good. Hopefully, this PCM will be the last of what has become a very long list of replaced parts. It's just about car show season, and I am ready to participate!

You'll need to go through the "CKP System Variation Learn Procedure" for that too.