Hey everyone, I recently bought an 05 F-350 and it's been having a misfire. Its previous owner said he had replaced 4 of the COPs, so I went ahead and replaced the other 4 hoping to fix the problem. Unfortunately, now the engine turns but it won't fire up. I removed them again, checked for debris, and put some more dielectric grease on the end of the boot, but it's still having the same problem. I'd appreciate any help as I feel like I'm in a rut now.

 

Pull the codes and see what you get. That truck is too complicated to guess what is wrong.

 

Unluckily, the CEL doesn't come on.

 

CEL doesn't need to come on to get codes..... have the codes read!