I was replacing the coils and found this (see picture attached.) Plus I have a little bit of oil in the upper intake, how does that oil get there, and how is that cylinder black...and what should I do?

2002 Disco2
125K Miles

Original symptoms were misfires reported on all even numbered cylinders, replaced cables & plugs, no improvement. Replacing coils when I found this.

 

Pitted leaking valve seats? Just a guess.

 

I think the term you're looking for is "intake runner". In any case, this is typically a timing issue. You don't really have much control over that, and I wouldn't worry about it as it's likely a product of your motor running so poorly. Once you get it sorted out, do an induction cleaning with seafoam or similar.

Also, did you consider the crank position sensor before you bought coils? It's a $75 part that very likely could be going at 125k, and something you might want to change anyway at that mileage.

 

I'd agree it was a valve issue if it motor wasn't running like crap to begin with.

 

Yeah, good point. Could be something causing a crossfire too. Firing the plug while the intake valve is still open. No doubt would set off all kinds of misfire codes.

 

That's kinda what I'm thinking based on very little information, which is why I mentioned replacing the CKPS. If it's failed the right (wrong?) way it can cause all manner of problems. It's much easier when they just up and die, or quit when hot.

 

You get oil in there because of your PCV system being dirty or the oil separator is missing or you are using the wrong oil and it is getting past the oil separator once the oil has thinned out.
As for the mis fire on all the even cylinders, I would replace the crank shaft position sensor first.
Drivers side of engine 3 o'clock position.

 

Finally finshed the coils and new gaskets. Test drive for 20 minutes showed no symptoms. However just to play it safe I think I may replace the crankshaft position sensor, that makes more sense than the coils.

Oil separator is present, not sure how to tell it's working, except if I find oil in my intake... I will replace that too, looks like the whole kit is $20.

Driving the family of 6 across a few states in July, want to take care of as much pre-emptive replacement as possible. Will post new thread asking what parts are most common to go out over 100K that can be easily replaced.

Thanks a bunch for the advice men.

 

Darylj & photocrimes, the engine purred like it was on the show room floor up till this recent issue when the checkengine came on and reported misfires. It hasn't been drinking oil either and gas milage has been extremely consistent for the last year. I'll replace the CKPS & PCV system, I hope those take care of the issue, a valve would be a major job even if I found some rebuilt heads.

 

Good plan. And do an induction cleaning to "clean up" the junk in your intake and elsewhere from the rough running.