I have a slight miss in my 05 FX4 after changing the plugs and cops. I used new motorcraft plugs (sp545) and cops and torqued plugs and the bolt holding the cop to the recommended torque's. I'm assuming that I must not have got the connector on one of the cops seated properly -- at least I'm hoping that's the cause! I did use dielectric grease on the cop connector (a small dab) and anti-seize on the plugs. I had 2 plugs breaks off and had to use the "special" tool to remove them. I was careful that nothing would have dropped into the cylinders by blowing out all dirt and debris around each plug prior to plug removal -- one at a time and then replacing before moving to next plug. I did pull the negative off of the battery as well.

Does my assumption seem the likely culprit in your opinions? After reading some posts here about similar issue, it appears to be the first recommended solution, but also wanted to ensure the dielectric grease on the cop connector wouldn't have caused issue.

Thanks,

Pat

 

Is it throwing any codes?

 

No, no codes are being thrown and the CEL is not on either.

Thanks,

Pat

 

I just reseated all the cop connectors and no change. Is it worth pulling the entire cop and reseating them again?

 

Could be a bad plug? Id hope not since those are the updated ones. Stranger things have happened. Also, what brand did you use?

 

Thanks, I hope not too!! Although will be easier now to remove and not worry about breaking them. :-) I used all motorcraft plugs and cops. I noticed I put the wrong part# for the plugs, they are the SP-546 and the cops are DG-511, not aftermarket, but definitely motorcraft.

 

 

Ok, thanks! I will pull the plugs and check them out.

I really appreciate all the replies! Thanks!

 

So I bought 4 new plugs and replaced one at a time and started the truck after replacing each one. It seems better, the miss isn't nearly as pronounced as it was. I can still hear it though and that's bothersome. I checked vacuum lines for breakage, the connectors to the cops and inspected the wires to the connector to ensure they weren't broken or frayed, etc.

Any other ideas? Is it possible that one of the cops isn't up to par?

I had 2 plugs break while replacing them initially, and I thought on one cylinder that the bootstrap of the plug might have fallen into the cylinder after using the plug remover tool. I never did find the bootstrap but I did use my scope and look into the cylinder and didn't see it in there either. Something still tells me its in there somewhere or perhaps now it may have blown out the exhaust port.

Thoughts on this anyone?

Thanks,

Pat

 

You used the dielectric grease on the outside of COP connector prior to sliding it in ? Did anti seize get on the plug strap ? you shouldn't need any anti seize with the newer plugs. what about COP boots ? were they replaced ?