Truck has 165k miles on it, prev owner had maint logs since truck was new. At 133k he had dealership change all 8 plugs. Then at 157k truck developed a miss and according to the receipt, dealership changed plug and boot on #3cyl and coil pack on #5cyl. I bought the truck with 158k on it.


Fast forward to now, driving home from work couple days ago truck starts shaking like a big cam'd hotrod and flashing service engine soon. Hooked up to handheld device came back P0307 (mis-fire #7cyl). So I put new motorcraft coil pack on and code went away as did the miss. Next morning drove truck 20miles to work, no problems. Get in it to come home, get about a mile from work, and same thing starts again. Shaking, loss of power, flashing service engine soon light. Run diag again, throws code P0308 this time (mis-fire #8cyl). Did some troubleshooting and at times truck will run normal sitting at idle then start missing randomly. Tried unplugging #8 coil pack when the missing starts and no change (continues to miss). Cleared code, started up truck ran normal, unplugged #8 and obviously the miss started. Plugged coil back up while missing and it continued to miss.


To me, that smells like a bad coil but IDK. Seems weird #7 would go then a day later #8?? So this morning I bought another coil pack and new motor-craft plug. Plan at this point is to change the plug and coil on #8 and see if the missing stops.




Any of you have any suggestions?

 

codes don't lie......... probably just a coincidence. Have had similar problems.

 

Truck is fixed, replaced all plugs and coils on #7 and #8. Receipt from ford dealer showing $500 charge and saying they changed all plugs 30k miles ago. NO WAY, these plugs were toast and rusted. I think the dealer took him for a ride.