gsmith2990

About a month ago I was driving across a few states in my 2013 Jeep Wrangler JK Sport and my check engine came on with the code P0306 cylinder 6 misfire. I had just replaced the spark plugs right before I left for my trip, everything seems to run just fine except when I'm in idol its starts to "stumble" or jump forward. When I got back home I had my buddy who helped me change the spark plugs take a look at it and they were all fine so we ran some sea foam treatment through the gas tank as well as the intake hose(I think that's what it was, I'm not great with cars that why I had him help me. after a couple days and once the sea foam had run its course every went back to normal, until about a week ago. The stumble and jumping came back but no check engine light. Has anybody ever experienced this before or know what I could do to fix it? Thanks!

rob_engineer

Just had this in a Hyundai. It was a bad coil. At higher rpm it was able to provide enough voltage for the plug to spark. At lower rpm it's voltage would drop and the engine would stumble, along with a corresponding misfire code. The code would go away when Rpms were higher. A new coil did the trick. Good as new.

Canvas

I have not had the issue but a buddy has and he swapped out the coil pack with another cylinder, reset the computer and waited to see if the code followed. His was #3 misfire and he swapped it out with the #1 cylinder and the discrepancy moved from 3 to 1.

I would swap the coil pack and see if it moves. If it does not then you have an issue with either the head, which is coverved under a recall or the sparkplug. Seeings how you just changed the plugs I would swap the plug with the another cylinder opposite of the coil pack. Process of elimination to narrow down what is causing your check engine light.

R/
Will

rob_engineer

FYI. Coil packs are so much cheaper on Amazon compared to in the auto store. Had to pay $80 for one in the store for the hyundai. On Amazon I could have gotten 4 for $50.