I had been trying to fix a single cyl4 misfire for over a year with no luck. I had checked everything including moving the injector, compression test, trace wires, etc., etc, and the code would pop up after a short drive. I have got a new head since my 0331 cracked and I thought may be I did a permanent damage to my cam bearings or something else causing the misfire. So last weekend I changed the oil with my usual 15-40w Rottella and Wix filter. I did it early only after 3000 miles mainly because we had a tough winter here in NJ. I have now driven over 400 miles of mixed driving and no codes. In the past I would have had to reset the code at least a dozen times for sure. So, I'm now wondering if this was pure luck or just coincidence. I did nothing else other than the oil/filter change using what I use all the time. Any thoughts?

 

You bumped something around the coil packs changing the filter?

 

Actually I had replaced the coil rail several months ago, more or less out of desperation and even giggle tested the heck out of almost all the exposed wiring with not luck. I'm still scratching my head....
Is it possible that the oil change affected the lifters/bearings by removing any left over coolant, etc.? I had done two back to back oil changes after I replaced the head just for that purpose.
Well, I'll chalk it up to another one of those unresolved Jeep mysteries...