Originally Posted by mikekerr

Like the OP, my plug was recently replaced prior to electrode ground failure. In my case the plug was replaced by a Ford Dealer in Western Minnesota in January 2018. Did the Ford dealer use old stock? Possibly. Did they charge me for a plug change that they overlooked? Possible, but it was cylinder #5 on the 5.4L, which is a very easy plug to replace so I find it tough to understand how a tech would miss #5.

It was very frustrating after the plug failure, that both I and the Utah Ford dealer could not get the truck back firing on #5. I replaced the plug, COP, and fuel injector, all with OEM. The dealer repeated what I did, along with a compression test. Six weeks later the Ford Dealer Tech gave up, unless I wanted to replace the PCM. I picked the truck up from the Ford Dealer, and the truck crawled home, running like crap.

I read one hundred pages on this forum's 5.4v board, likely over a thousand posts. Came to a thought that I either had a carbon issue, or a plug seating issue. Researched the Champion plug for the 5.4v 3v, it has a very different design than the latest OEM. It has a conventional electrode ground, more threads, a wider sealing lip to the head, and a larger "bolt" to secure it.

It is important to share this story, someone shared their story which led me down the path I went to- which resulted in a running truck that was headed for the junk yard. I wanted to share my story as maybe it will trigger some course of actions for someone with misfire issues.

Originally Posted by Lorrainethef250

I dont think I've done anything wrong with it.. it's been babied its whole life. I dont touch major engine components or ignition systems for this exact reason (except this one time). I just do not know if it was a possible failure of the plug, or if my engine is too hot, or what's happening. It's been driving me nuts.

Originally Posted by Noahpatton

I’m having this same problem right now. Did anybody ever locate the guard (electro ground) and if not did it ever cause any issues with the trucks down the road. I have a scope and I see no sign of the guard in the cylinder

Originally Posted by ford390gashog

Something here is wrong, the current plugs are PZH and have been since 2012. The PZK plug is the original to the engine. The new plug you have next to it shouldn't be used, the PZH plugs eliminate the welded portion. Where did you get the obsolete new plug from?