SES light came on and code is P0306, #6 misfire. I've been reading about the coil packs on the F150 5.8L. Triton engines
going bad. Should I replace the coil pack and plug, since they are not covered under extended warrany? Truck has 48K miles on it.
What is the cylinder layout of this engine? I don't have any maintenance manuals on this truck.

 

Cylinder layout is:

4 - 8
3 - 7
2 - 6
1 - 5

#4 is rear passenger side cylinder and #8 is rear drivers side cylinder.

You could swap COPs 5 & 6 and see if the problem moves.
If it starts failing on cylinder 5 then the coil has a problem.
If it continues to fail on 6 after the swap then the spark plug may be a problem.

Also check that the #6 spark plug hole does not have water or oil in it. If you have an ohm meter you can check the COP resistance.
The connectors should read .5 ohms and either connector to the spring of the COP should read 5500 ohms.

 

Thanks, I'll try that. Right the engine is a 5.4L. My wife car is a 3.8L six, and it two has problems. Had .8l on my mind