I own a 2010 Ford Edge SEL limited with 110K miles. Check engine light P0306 came on after replacing all plugs and ignition coils with Motorcraft original equipment. Still getting idle bounce after engine warms up. Sent PCN for bench test and came back without symptoms. Frustrated and thinking it’s short in wiring harness. Harness is no longer available from Ford. Any suggestions? Thanks

 

I can appreciate your situation, but just because you ran out of parts to replace is no reason to give up.lol.

This could require you to remove the valve cover and look for something there,like possibly a broken valve spring, bad cam,etc.We could give you a list of things to check out, but don't want you to keep replacing good parts.

If you suspect a wiring problem instead of looking to replace an entire harness which can become a can of worms, you might consider investing in a small multimeter which can help you verify continuity in a wire and save you a lot of unnecessary work. If you are not familiar with doing that check ,the hardest part is purchasing the meter which can also make checking fuses a lot easier. There is something to be said for when you find the cause and repair it What do you think?

If the misfire code is always the same cyl, then you confine your efforts to everything related to that cyl.