Need Advice and help Engine Jeep liberty 2003

[mrlavalamp]

I don't think you can rely on the results of your old tests in comparison to your newer advice. The compression test was a year ago, you probably need to disregard that for now as a primary symptom, or go and have the recommended compression and leak down tests done.

Pcm and compression testing are not related, compression tests should be completed with spark plugs removed so engine is not running.


List in the sticky says that code is high oil pressure. If it does that when it's cold at startup but goes away when engine warms or temp outside warms, then it could be your type of oil.

What oil are you putting in it? Last change?

 

[Bandini]

Same problem w/misfire

Just to throw in my experience, I'm having a very similar maddening problem with my 2003 KJ Renegade 152,000 mi.

Consistently get P0303 P0306 - CEL is consistently on but occasionally will go off for periods (ranging from in between starts to a week). But it seems it only misfires on cold start and very minor at that - I have to really pay attention to notice it (slight vibration basically).

I'm not even remotely a mechanic but I have replaced all plugs, moved coils around, I did the sound test on the injectors which seem to be firing normally (although, with intermittent misfire who knows). I have also run one tank of techron and two tanks of lucas fuel injector cleaner. I ran the thing for a 200 mile highway drive with the injector cleaner in the tank - still getting the CEL, same codes.

My mechanic (old school mechanic) basically told me to keep driving it and if it gets worse or more consistent bring it in so he can diagnose but didn't think it would be worth it to start trouble shooting (I've been using him for 30 years so I totally trust that he is just trying to save me money). I've dumped about 7 grand into the liberty in the past 4.5 years during which time I have put about 40,000 miles on it. I don't want to dump much more money into it but I don't really want a payment either.

That said, wondering if I should bring it to Jeep dealer to get them to diagnose - I really should bring it in there to have the airbag recall done anyway.

In my own research I have read most of what has been reported in this thread as well as ASD Relay (seems highly unlikely) cam sensor, O2 sensor, clogged cat, PCM/ECU, wiring, etc. etc. I've also read about the TSB calling for valve guides, valve locks etc. etc.

For the most part, it runs great... maybe I should just drive with my thumb hiding the CEL.

I - have - no - idea.