2003 F150 Misfiring

My F150 has only 40,000 miles and it is misfiring. Anyone know what would be the problem. Installed new sparkplugs and same problem after a short while and the service engine light came back on.

The Coil On Plug (COP) modules are a weak spot. It will FAIL emissions if it is misfiring, and if it actually does fail, Ford whould cover the repairs.

The Coil On Plug (COP) modules are a weak spot. It will FAIL emissions if it is misfiring, and if it actually does fail, Ford whould cover the repairs.

How would ford cover the repair with 40000 miles? Warranty is good
to 36k unless he bought an extended warranty

not to state the obvious, but if the service engine light came on, do you have access to a code reader? If not, it may be cheaper (in the long run, rather than troubleshoot yourself without one, swapping parts etc.) to take it in to a shop and get the problem code read/analyzed..unfortunately "newer" vehicles are run by computers, but then again, problems can also be diagnosed easier. I for one (being my own mechanic) invested in a good scanner, and have never regretted it. The cost was recouped rapidly..would have cost me the same with about 5 trips to the shop, just for a diagnosis. Good luck.
Steve

Most autoparts store will scan the error cades for free now a days. It's a ploy to get you to buy your parts there.

mine did the same . have an auto part s find out which cylinder is misfiring. it probably needs a new coil on that cylinder $50 at auto zone that is whhat i had to do