MDeal5

I looked through the forum and haven't found anything about this, but I've got a problem with my 4.7l in my 2001 Grand Cherokee that has me stumped. In a nutshell, the "personality" of the engine changes about every 7th or 8th time the engine is cranked. Most cranks, the engine starts up and runs as well as any higher mileage engine I've ever had. But every 7th or 8th time I start it, it feels like it is missing on at least 2 cylinders. It clears up around 2,000 RPM and runs significantly better. So I've checked the vacuum, and it says that everything's tight. I've checked the fuel injectors with a stethoscope and they sound good to me. Changed the plugs and it improved, but problem remains. I was getting a P0601 code, but replaced the pcm, again an improvement and cleared the code, but issue remains. If the engine ran on an old timing chain, I'd swear that the timing was floating or the harmonic balancer was bad, but I don't know if these reluctor ring things can float like that... I have not yet checked the cylinder compression, but the good and steady vacuum reading makes me think that's not likely the culprit. Anybody got any suggestions or a similar experience?
Thanks!

czettlera

Have you checked the fuel pressure? maybe one or two injectors are leaking, and that cylinder starts too reach. If it doesn't hold the pressure for a few minutes after after shutdown, than this can be a possible cause.