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Discussion Starter · #1 ·
So, I'm getting a P0306 code, which is a misfire in number 6 cylinder. I have checked as many of the vacuum lines and fittings as I can follow. I have replaced the coil pac, and installed new spark plugs, confident that I had solved the issue, but I am still getting the same code.

So, where do I search next? If it were an injector issue, wouldn't that show a different code? I thought about swapping a couple of injectors to see if that shows an injector issue, but I didn't want to tear an o-ring or cause a bigger issue.

Any help would be greatly appreciated.
 

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Could be a carboned-up valve seat, could be a bad injector, could be several things. I wouldn't worry about tearing an o-ring while moving the #6 injector elsewhere to see if the misfire stays where it was or if it follows the injector. Plus auto parts stores sell inexpensive o-ring sets for the injectors. Just be sure to clean/flush the o-ring seating surface with something like brake cleaner, WD-40, etc. before reseating the injector. Dirt can fall down onto the o-ring seating surface while pulling/replacing the injector.

Carbon build-up can be a problem if you tend to drive extra-conservatively and never rev the engine up to higher rpms or accelerate hard to high rpms one in a while.
 

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Discussion Starter · #3 ·
Could be a carboned-up valve seat, could be a bad injector, could be several things. I wouldn't worry about tearing an o-ring while moving the #6 injector elsewhere to see if the misfire stays where it was or if it follows the injector. Plus auto parts stores sell inexpensive o-ring sets for the injectors. Just be sure to clean/flush the o-ring seating surface with something like brake cleaner, WD-40, etc. before reseating the injector. Dirt can fall down onto the o-ring seating surface while pulling/replacing the injector.

Carbon build-up can be a problem if you tend to drive extra-conservatively and never rev the engine up to higher rpms or accelerate hard to high rpms one in a while.
Thank you Jerry. I'll do some more trying.
I can't imagine it being carbon build-up, as I'm not real easy on the Wrangler, however, I did buy it from a guy who probably never left city limits with it.

Thanks again for sharing your knowledge. I appreciate it.
 
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