Did you check the gap on every spark plug before you installed?

 

I did check the gap to .44 before installing. It appeared the old plugs had a bit of oil on the threads with only $58k miles...common or sign of another issue?

 

Just double-checking here. I'm pretty sure cyl 1 is passenger side. I wasn't clear from your post that you may have been talking about only the driver side. Other than that, my cyl 1 misfire was coil related. Did you try swapping coils?

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Yes, it's the front cylinder on the passenger side. I originally did change the plugs only on the drivers side as they are covered by the intake manifold, but after understanding the P0301 was related to cylinder 1 on the passenger side, I've focused attention there.

I have not tried the coil swap yet, but will try that next. Its interesting that I didn't even touch the coil/plug on the passenger side during the oil cooler replace...if that's the issue.

 

Check this post.. It is not exactly the same codes; however, it might prove productive: Codes p300 - p202 - p204 - p206 TECH TIP.

 

Check this post.. It is not exactly the same codes; however, it might prove productive: Codes p300 - p202 - p204 - p206 TECH TIP.

Thanks Jay...I will read through this post shortly.

 

There should be NO oil on old plugs when you remove them.

 

There is oil naturally present in the combustion chamber, and thus on spark plug, from the PCV system. So, no oil on plugs is impossible.

 

Good combustion indicates that oil should be a burnt oil (powdery) not a wet oil.
So there should be no oil residue left in the combustion.

 

I did have to touch the fuel rails, injectors and injector wiring during tear down and rebuild, but felt was careful and gentle with wires, etc and cleaned the injectors.

Tell us more about what you did when you "cleaned the injectors".

 

Mainly wiped down injector spray base and around where the seals seat. Was surprised by the amount of grit around that section of the lower manifold. I have a new replacement injector that will be going into cylinder 1 tomorrow.

So far, coil pack and new plug at .44 have not resolved code. Inspected the ground wire suggested by jay2011jk and everything looks normal.

In addition to the new injector for tomorrow any other suggestions of what to inspect while I'm in the lower manifold?

 

Is your jeep idling rough? Cold or at operating temps. Also intake manifold gasket perhaps on cyl #1 was a possible cause for misfire.

 

Welcome to the Forum, from Cave Creek AZ.

 

Now you can replace the oil cooler on the trail.