Installed new plugs on a major tune up on a '06 5.4 with aprox. 120,00 miles. Truck ran ok Still Had major pwr. problem. I took it to dealer and had a Diag. ran on it , came out 2 cyl. were not getting it done. Tech. recommended cop's, which I replaced with after market's. Now about 1 month and maybe 2,000 miles I noticed it was again losing power. Just for the heck of it I removed the 2 plugs from the above mentioned problem cylinders. One of the plugs had the entire tip - end burnt off I mean the entire electrode was gone I don't know how it was not skipping, but it wasn't. The other plug had just started to burn or maybe fracture the ceramic around the electrode away> I removed the remaining 6 plugs and they looked great. Has anyone ever seen this? And does anyone know what might of caused this to happen? I am pretty sure the one clylinder with the badly burnt plug has to have some type of damage. Anybody got any idea's?

 

Were a couple of bad injector issues in the '06-'08 models that might have something to do with it. When an injector goes bad, the engine can go lean and cause all kinds of catastrophe. I'd look into that right away before anything else and if that is the issue, thank your lucky stars that it was your plugs and not your engine that bit the bullet.

Did you notice any pre-ignition, or detonation under load at all when the power started dropping off?

 

Thanks for reply, But I was not driving it at the time, a friend of mind was pulling a trailer to Kentucky for a chairity thing his church does. He said it would not even pull a hill 30 miles a hour, and smelled real hot, but did not run hot,and did not lose any coolant. He called me late at night and I suggested for him to find a hotel and spend the night, which he did. the next day he dropped the trailer and drove it around while talking to me and it was running great. I told him to secure trailer., and dead head back here and swap for a 02 F250 --7.3 I had just finished. I checked the codes on 5.4 and it showed #4 cylinder misfire I cleared it, and drove it around for couple of days and it does have a serious noise in the bottom end. ? do I need to pull cab to remove engine?