Background: 1999 Mazda B3000 Troy Lee Designs 174,000 miles.
Bought the truck in August of 2011 with a cylinder 5 misfire. Replaced the head due to the valve seat being shot. While I was at it I replaced all spark plugs, plug wires, coil pack, iacv, pcv valve, egr valve, egr valve pressure sensor, #5 fuel injector.

Truck has ran fine since august until a week ago. Truck began throwing and idle air overspeed code. Replaced iacv (again), tps sensor, coolant temp sensor, and camshaft position sensor. No more overspeed code.

A couple of days later i get a code for Cyl 5 misfire. Pull the plug and the electrode is all but gone and the plug is caked with carbon and the ground is powdery white. Pulled another plug out of #6 ground was a little white but the electrode was fine. Put a new plug in hole #5. The truck ran fine for two days until today. Got the cyl 5 misfire again. Pulled the plug. The color wasnt bad but the electrode was slightly bent. Any ideas?????

 

There's something going on in #5 cylinder, and it isn't good. Do a wet and dry compression check on all cylinders to see how #5 compares.
I assume it is the ground electrode that is bent, regardless, something in the cylinder had to hit it: valve, valve seat, piston crown (which is only likely if the piston is destroyed).
Let us know what you find and we will be standing by to help.

 

Sounds like something is up with a valve or piston(unlikely). Check compression or pull the head again!

 

the first plug that i pulled was not bent at all. just extremely torched if u will. ill try and post some pics up tomorrow. a buddy has my compression tester.

 

Could be due to an error in your fuel/air mix in the cylinder.

 

This site should help you out a bit...
http://www.gnttype.org/techarea/engine/plugs.html

 

Update. The spark plug electrode was bent when i got the plug. I went to autozone to get a new one and two boxes of motorcraft plugs had bent electrodes. Paid a shop to try and diag the problem. fuel pressure is good, vacuum is good, compression is good. Basically cyl 5 keeps leaning out plugs. They said thst the egr system was causing the misfire. Any suggestions?

 

If only that cylinder is burning lean, check for a leak in the surrounding head gasket. Also, check the valve seals for that cylinder. Just ideas

 

Its a fresh cylinder head and i went trough a can of starter fluid looking for leaks