Just got my F150 about 2 weeks ago. Replaced the sparkplugs, which required me to buy the removal tool, and the coil packs. The wires were fine. Took it back to the shop for a scan and read Cylinder #8 misfire. Changed the coils around and still cylinder 8. Checked the sparkplug, worked fine. Could it be an injector? I unplugged the injector and hooked the wire to a tester and it worked. I seafoamed and put lucas injector cleaner in the truck. Any ideas?

 

I have the same exact problem with cylinder 3. I even pulled the plug and tested it with the plug wire on a lawn mower and it fired fine. I swapped #3 and #5 coils. At idle I can disconnect #5 coil and notice a difference. When I disconnect #3 coil while idling there still is no difference. I thought about an injector too but the code is for a misfire. P0353. I'm ready roll this thing off a cliff somewhere.

 

Is the misfire constant or intermittent? How did you check the plug? What did it look like when you pulled it out? Was it wet? Are there any trouble codes?

Johngeorge, could you please start your own thread? I'd love to throw you some ideas, but I don't want to derail Southern_thunder's thread.

 

I did. I sent you a link. Sorry if I overstepped.

 

Not at all, I just posted in your thread.

 

The only other thing it could be is compression loss... I know it may be a PITA to retake out the plugs, but it would be better to not assume something so basic or easy to check.... rule something else more definite than electrical testing

SIDE NOTE that the adapter to check compression on this particular motor does not come WITH any compression it must be orderd by application. Easy find on Amazon or Napa