rjandrus

Hi all, new member but longtime user of this forum.

I have a 2004 GC Limited 4.0L w/ 220k miles. It keeps throwing a P0301 code. I changed the plugs first time the code threw and all was fine for months. Then it started again. Replaced the rail, and saw the plug looked fouled. Replaced all the plugs again (they're cheap) and it ran OK for a while. Now it's back but I get a bit of a oil burning smell. I think the two are unrelated because I do have a small leak somewhere below and I think it's the hot engine for the smoke issue.

My misfire question is this, I was thinking of replacing the injector, but at $50 a pop, that's a commitment. Is it worth replacing just one, or should I do all 6?

This Jeep as been paid for forever and has always done me good, I hate to give up on it for something I can eventually fix. I'm shooting for 500k!

Thanks all - Bob

Bustedback

Swap #1injector with #2 injector and see if the misfire changes to P0302. If it does then you have a failing injector. I have not seen any injectors cause an intermittent misfire though, it is either working or not. Do a compression test on all six cylinders. If #1 is low, then do a cylinder leak down test and find out where the leak is coming from. If you hear air escaping from the tailpipe, you have a bad exhaust valve. You hear it coming from the throttle body, you have a bad intake valve. If you hear air coming from the oil fill cap, you have worn or broken piston rings. You could also have a coil rail that may be crapping out, that is a hard one to confirm though. Do the mechanical checks first before you spend any money on parts.

Just reread and seen you already replaced the coil rail. Did it come with new boots?