ok guys, bear with me. had my 2001 f150, 108k tuned up 3 weeks ago by former ford tech of 25 years. he replaced all coils, plugs, fuel & air filters, cleaned fuel rails, sensors. used all motorcraft parts. truck ran great for 3 days, then misfired bad. he as well as local dealer checked injector flow & compression, all ok. they have replaced #7 coil & plug and #7 injector twice over. PCM has been reset. still misfires. #7 usually seems to be the favorite. it's been on a WDS machine, found nothing. what's the next step??? anybody, somebody???????????
thnaks, i'll check. all plugs & coils are new, including boots. threw code for #1 cylinder yesterday, changed plug & coil again. trucks running great now but for how long don't know. it's like chasing a ghost.
Swap the coil and plug from #7 to a different cylinder. See if the problem travels with the coil and plug. If it does then move the coil to another and go from there. If it follows the coil then the coil is bad, if it doesn't the plug is bad, if it stays on #7 you may be taking the harness apart looking for a break or possibly a computer problem. I just tuned mine up and had a missfire on #1........I felt like a DA when I took the plug and coil out to find the gap of the plug was closed.
tried the swap a few times. computer was reset by dealer. #7 cylinder has the 4th new coil & is ok. my personal ford mechanic changed coils all around twice. i'm wondering if motorcraft has or had a bad batch of coils they didn't pull. i'd like to talk to a rep about that. i pulled my boat with her today & she never missed a lick, i'm hoping the goat rodeo is over.