I developed a miss in my 97 F150 w/ 4.6 about a week ago. I went to a dark place and popped the hood to witness the #2 and #4 plug wires lighting up like Christmas. #3 may have been as well. Upon pulling the #2 wire, I noticed what appeared to be a small amount of corrosion, so I pulled the plug. As I pulled the plug up, the threaded area was covered with oil but it appeared to have been burning clean upon inspection of the electrode. The same with #3 as well. I didn't bother pulling the #4 plug because the plug wire also had what appeared to be oil on it. I put new plugs in 2 & 3 and new wires on all eight. Upon start up, it ran smoothly but after I got the engine up to speed, it started missing again and has been present since.

My oil pressure has remained strong and there was no water in my oil when I changed it about 2 weeks ago. I'm hoping it's a bad cover gasket and not something worse. Is this wishful thinking?

 

Did you check the coil pack?

 

Yes. Forgot to add that. Replaced both of them.

 

Was the oil in the sparkplug holes as well? I know you said #4 had oil on the boot so that oil is getting there from the outside. Probably since the oil fill cap is on that bank some of the oil is from spillage when adding oil. The plugs that had what appeared to be oil on the threads could be oil that ran down from exterior as well when the plug was loosened. It could also be carbon that is getting gas soaked from misfires and looks like oil? If you are getting more missfires then other plugs may be fouled as well or you have enough oil contamination in the plug wells to generate misfires. Change all the plugs as just changing two is a waste of time. Also since someone is going to ask this, what brand sparkplugs did you install?

 

I'm hoping that is the case. It was definitely oil, pretty clean at that. I installed Motorcraft plugs and the ones that I removed were Motorcraft.