I had a COP fail last week causing a misfire. I replaced it, but again today it started misfiring again.

I noticed some oil on the COP I replaced. Does this indicate a leak from the valve cover gasket? Can't really imagine the oil coming from anywhere else.

 

I can't imagine it anywhere else either, but are you sure it's oil? Somehow all sorts of gunk gets in the nooks and crannies of the motor and some of it takes on an oily texture.

Is it the same COP?

 

how do your spark plugs look? I just had misfires on my van and it was the spark plugs.

 

It was the first time this COP has failed. Last time it was cylinder 6 and this time was cylinder 8. I don't know which cylinder was misfiring the last few days as it didn't miss at idle nor did it throw a code. I replaced all of the plugs on that side and the valve cover gasket to make sure no more oil spills in. It was pretty obvious that oil was sneaking past the bolts and dripping toward the plugs and COPS. Too much gasoline was on the motor when I finished tonight, so I'm letting it evaporate over night before I start it up again. Time will tell!

 

I do not know about your oil issue but I had a misfire in my 2000 Gt, replaced plugs - still there, then my mechanic told me to replace the cop to plug boots>success!

 

Mine started to go right at 100K on my Mustang and my F150. I put sets of Accel COPs on both. One of the Accel coils failed with 36K on it in the truck so I replaced that one and haven't had any more trouble.

 

Replacing the gasket seems to have fixed it. I have had two COP's fail, but replacing those seems to have it still running alright.