Hey all,

I have a 2006 5.4 3v f150 74,000mi. Last summer I began to have missing issues. I had two plugs replaced for $200 a pop at the dealership and that fixed my problem. This fall started missing again on cylinder 1 but only missed when I really get on the truck. So to start I just swapped cylinder 1 and 5's COPs to see if I had a bad COP, but it still missed on cylinder 1. So found a guy that would change all my plugs, and 5 broke plugs later he had all new plugs in and it was running like new again without any new COPs. This was sometime in November. January I began to have a miss on cylinder 5 again only at heavy throttle. Went and got a new COP thinking surely a new plug wasn't out but didn't help anything. Took it back to the mechanic that changed my plugs still being under warranty. He worked on it all day trying to figure something out saying the plug checked out fine. But after the new plug he couldn't get it to miss again. A month later it is missing on cylinder 5 again at heavy throttle.

Any ideas of what my problem is?
All of a sudden hit 70,000 and my truck starts eating plugs this doesn't make any sense at all and why would keep it happening on cylinder 5?

Thanks

 

Do you have an after market intake that could be causing a lean condition?

 

No I don't have an after market intake.

 

What brand of plugs is in there? Have you tried swapping COP's again? I see you have a Gryphon - have you tried putting it back to the stock tune?

 

I believe he said he installed champion plugs. Haven't tried swapping COP's again. And the truck has been on stock the whole time this has been happening.

 

Get the Champs out of there and put a set of Motorcraft SP-515's in. Some people have had good luck with the Champions, others have not.

 

With 8 to 1, just figure you've got plugs for your lawn mower for a long time to come!

 

You also have to check those injectors. I'd do that pronto. Friend of mine with an 06 Expy had one do the same thing for awhile. Exactly the same except Champion plugs weren't involved AFAIK. It eventually Hydro-locked. $7500 later, - it was up and running again with a different engine.

She had good insurance and it looked like either Ford or her insurance was going to cover it. It went round and round with neither covering one penny of that expense. Fortunately, her dad came thru for her. The kicker, she's a team leader @ Ford Dearborn.

 

the misfires from the plugs weakened the cops....champions aren't the best choice for replacement plugs, the motorcraft sp515 is and now you'll also want to change the cops

 

I wouldn't change the cops yet, but I'd definitely replace the boots if you put Champions in there.