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I had a miss fire.

755 views 4 replies 4 participants last post by  Fifth Horseman 
#1 ·
I had a miss so I started dissconnecting one coil at a time until I found the miss fire on #8 . When I removed the coil I found the the spark bore was full of rust and the spark plug was not firing and the plug itself was very rusty.

After I cleaned out the rust I removed plug and cleaned where the plug seats in the head. Replaced the plug and it runs great. The head is aluminum so the rust had to come from the plug. I also think the plug was shorted. Probably the main cause of the miss rather than rust on the plug seat. When I change plugs I always save the best 2 just incase one of them goes bad. Good thing because they never keep them in stock and takes a few days to get them in.


Just can't figure how moisture got in there to begin with. There's no coolant leaks etc. Well I did have coolant puke out last summer when the relay to my electric water pump took a crap on me. You'd think if that was the cause it would have missed before now. I had it started about 3 weeks earlier and it ran fine

The rest of the plugs are fine. The spark plug boot looked fine so I have no idea how liquid found it's way in. Since I have extra coils I replaced the coil and boot just for good measure.
 
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#2 ·
Can i get a pic of where the hell the plugs are i know it's a basic question but i need to check mine tomorrow. The seller said he sprayed out the engine bay! and now i have a mis
 
#4 ·
It probably just got moisture in it one time when you washed the engine... it will stay in there for a VERY long time. I recall one back when I was running a vortech years ago lol. I washed down the motor like I often do to clean it up and I never bag a thing. The way I see it is if there is a problem then it will help me find it (like a bad plug boot or something, I dont spray water at the fuse panel lol). Well once a couple days after I washed down the motor I started to get a miss under boost that would sometimes clear up and sometimes not. Never enough to throw a code. I have a few other cars so I just stopped driving it until the weekend. Well several days later I pulled the plugs and one of them had about 3/16" of water in the damn thing and when the motor gets hot it vaporizes and is enough to short the block if the boot isnt tight anymore. I said hell with it and swapped all of the COPS because I had been thinking about it. I put MSD cops in and theyve been there for 5 years no no more problems. I guess I'm one of the few to run both MSD and accell with zero failures.

Dont dismiss moisture in the hole. It only takes a small amount to do crazy things. One of my practices now is I put a small amount of dielectric grease on the outside of the boot around where it meets the cylinder head to help the boot seal and prevent dust and moisture from getting in. I also always use it on the inside of the boot where it meets the plug to ensure a good seal against the plug. I've never had another issue.
 
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#5 ·
I had a similar issue with moisture appearing and going in my plug holes. Turns out the intake cylinder head surface was pitted bad and the manifold was not making a good seal causing coolant to leak out. I had to take the manifold off and epoxy the surface and then sand it flat. Im guessing a imbalance in the coolant contents may have caused some oxidation/pitting and killed the cylinder head. Interestingly enough though the plastic on the intake manifold was ate up too ended throwing it all away. Ive been using ford approved green coolant for fleet vehicles, I have not had problems since.
 
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