I'm having a spark plug coil issue. I change a coil pack every 3 months. The last one was on cylinder #3. I have always brought it to the same mechanic. They clear the check engine light and replace the ignition coil. I recently had the mechanic change a heater core and they replaced the intake manifold.This miss fire is at 40 mph, and in over drive at low rpms. The car still smokes the tires at take off. Also it seems to be idling fine. Any suggestions?

 

Misfires often occur when the engine is under load. If your mechanic is using aftermarket ignition parts, I would insist on Motorcraft ones the next time you have an issue.

 

Thank you Sir