1998 f150 missfire after tune up

[pauley]

ok i have a 1998 f150 as a dd and after a coil pack wires and plugs i have a miss on cylinder four i did a spark test and it all seemed to be ok i checked for voltage and pulsing ground at the connector so me thinking im all done testing threw a fuel injector in it and still has a miss so i need some help and i would like a plug wire routing diagram and any other ideas if possible hopefully not a valve or weak cylinder problem.

 

[pauley]

ok i tracked the problem down to a severely carboned up spark plug but i do not understand why it would do that i replaced all plugs wires and one coil pack less than three mounths ago used oem recommended auto lite double plats with proper gap.

 

[97ford50x]

i hve run into this at the shop a few times what i have found is a cracked plug

 

[pauley]

the part that gets me is that this thing ran great for like 4 weeks after the tune up then randomly it got screwed up again. there was globs of un burnt fuel on the plug like the stuff that clogs egr ports.

 

[Sams01XplrSprt]

so does ur f150 work now or still missfires

 

[pauley]

it works now however i have two egr codes that read egr insufficient flow detected and egr to much flow detected i think it may be time for a egr valve and to clean the ports in the intake manifold. (i replaced the dpfv when i did the plugs and wires).

 

[Ranger Al]

You may think it is crazy, but I've experienced the same situation with mine. I had to get Motorcraft plugs, cause the Autolite plugs will have light show inside the engine compartment (missfired).