Detonation on #2 only, 2008 Jeep Liberty 3.6L

My daughters Jeep Liberty 3.6L w/ 73,500 miles (purchased used @3 months ago) got a P0300(random misfire) and P0302(misfire #2). I replaced all plugs as the gap was around .060+ on all of them and this is when I found the #2 to have a bad detonation issue. All plugs looked good, maybe just a little lean but still “normal” except #2. It was dry, with a “rusty” to ash white tint and dry buildup down inside. There is also black pepper specks all over. I scoped the cylinder and there is a lot of dry build up also, not oily at all. I checked compression on #1, #2 and #4 and all were @170psi. I also changed the coil on #2 also. And just for the heck of it I replaced all the lifters and bank #2 head just because I know this is a common issue on that engine.

After @50 miles on the new plugs and coil I took #2 out and it was “peppered” and white ash in color. The other plugs still looked like new except for a tiny bit of carbon.

What am I missing or what could be wrong?

• This topic was modified 2 years, 2 months ago by  Tom Prebelich.

Topic

[Richard KirshyParticipant]

Just taking a shot in the dark here..
Possible faulty or partially clogged fuel injector

[Tom PrebelichParticipant]

Richard,

I appreciate your reply!
That is what I changed this morning. I think that’s what it’s going to end up being. I know it was working but could have a clog or not working 100%. I will update in a couple weeks when my daughter gets back from college.

[Author]

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