Hey guys I'm new here and driving an f150 I upgraded from a ranger in January! But I've been having some difficulties out of it this last week. It's started feeling like its misfiring when it's idling. Yesterday the check engine light came on and it's throwing a misfire on cylinder 8. I just broke 100000 miles. I'm thinking it might be a bad coil pack but I just wanted to get another opinion before I moved forward with replacing it.

 

Replace the spark plugs first. If they are original, they are way overdue. They probably are original because people tend to leave them alone due to the issues with changing them.

 

And if you replace them yourself do a lot of reading about what you may be up against. They tend to break and have to be extracted. Can be done successfully but you need to read up on it and be ready.

 

Yea they probably do need to be changed. I'm concerned with doing it because of all the issues.

 

Well - 100k - you either do it, have it done, or get rid of the truck. If you keep driving it like this you will kill and possibly plug up the cats.

 

^^^^ Agree completely ... and another reason, I believe misfires (which frequently occur on these engines under load at low RPM) causes the timing chains to slap the hell out of, and break, the plastic timing chain guides which leads to other problems. No need to ask how I came to believe that.

 

Suggestion from experience.


Replace all 8 plugs and coils do not just do one.


otherwise you will be doing one off's until you get through all 8.


It's really not that expensive of a job and you will notice a big difference.


I bought my 00 5.4 litre with those issues and I knew about them when I bought it. I changed 3 coils and plugs separately then quickly realized I bought the same exact part number coil on ebay (from an auto parts store in FL) for the cost of 1 and a half of the ones I bought at a local store so I got all 8 and 8 new plugs at 140,000 miles and I retired that truck at 215,000 miles and never had to touch a coil or plug again.


Peace of mind and a good running truck...

 

You may not need any coils - and the cheap Ebay coils have very mixed results. Most OEM coils last well past 10 years and 100k miles.

 

Agreed so watch what you buy don't only buy for price but verify part numbers.