99 4.6L Scab, 141k miles, usually run 87 octane with mixed city/hwy miles. Has been regularly serviced.

I've changed plugs for 30 years and have never seen only 1 plug so much different than the others. All 8 electrodes are light tan and show no abnormal wear - except for #1 cylinder. The elctrode is deformed; looks like someone pounded it flat! Any ideas? Could the timing for #1 cylinder have caused this? Can only 1 cylinders be affected without affecting the others?

 

yikes! Are you sure it was the correct plug? It seems like it was too long , causung the piston to hit it. Did you hear any metalic sound while running those plugs???

 

I have heard some pinging lately but I attribute that to garbage gas. I've recently gone back to Chevron and am using 87 octane; it was not noticable when I ran 89 octane garbage gas.

The electrode is still there, has a bend in like it should, but looks like, I don't know, pounded almost flat due to detonation? preignition? wrong timing in that cylinder? I dunno!

I've had the truck 2 months, bought it used with 1 owner who kept it serviced regularly. It did have the original spark plug wires; I should assume the original plugs as well. It runs fine; I was dumbfounded when I pulled the plug out.

I've got digi pics (not great quality). If you want to see them, drop your email.

 

Well, if the electrode is there, then it's not getting slammed by the piston, which is very good news. The pinging is likely because you're running on 5 cylinders b/c of the bad one. It has to be a problem with that cylinder only--if it was a fuel or ignition problem, it would be system-wide. Maybe a problem with an injector that won't shut off? I don't know, this is now beyond my limited knowledge of cars and engines. I'm sure someone elese here has some ideas.

 

Thanks for the reply! I may give the Ford house a call this week unless someone else on the site has an idea.

 

Decided to use my head, got out the multimeter and ohm'd out #1 wire. 4.86 on the 20K scale but would vary to 12 or 14+, or even open, when I moved the wire at the sparkplug boot. All other wires, although varied in lengths, did not change resistance noticably when moved/rotated/gyrated at either end.

Must have been the wire. Increases in resistance causes increases in amperage/current flow, right? I'm not an electrician.

 

wouldn't hurt to start there. Just pull that #1 plug often to keep an eye on it till you know the problem is solved.

 

Thanks, jimsa. I appreciate your interest.