Originally Posted by
Bluegrass 7
The answer to this kind of issue has been posted here many times.
Coils develope shorted turns from heat ageing and cause missfire under light throttle loading in OD at speeds between 45 and 60 mph.
These coils will even cause a minor hesitation flutter off ide from a stop but then goes away depending on if the engine heat is acting on them at that moment.
This condition is not a 'hard' fault so won't set a code or lamp you can see..
I have a 2003 F150 with 160k doing the same thing. It usually does in the worst while in OD at lower RPM's with light acceleration (not enough to kick down out of OD) I figured it might be a COP but didn't have any codes. So I started off by changing the fuel filer (didn't help), then I changed the plugs since it was about time anyway (didn't help). So now I'm back to the COP's but I hated to just start changing them out without knowing which one. The plugs all looked about the same, a little white but not worn too bad. All the boots on the COP's looked pretty good as we changed the plugs. Is there a way to tell which one is bad without getting a code? Or would you buy one or two new ones and just change them one or two at a time until finding the bad one. Any ideas would be appreciated.