Misfire

[chewy97]

I'm sure that I'll get murdered for posting this but I can't find the information that I am looking for. My 03 4.0 ranger keeps throwing codes p0304 p0316 I have read about random misfires and what to do to narrow the problem down to the cause. I have changed spark plugs and wires. I know that the coil pack fires 2 cylinders simultaneously would it be possible that just the number 4 coil is bad? Or could it be something else causing the problem?

 

[adsm08]

Ignore the 316 for now, it's secondary to the 304.

Yes it is possible for the coil pack to cause a miss on only one cylinder. What happens is the secondary windings break, and when it breaks closer to one side than the other that side can't fire enough, and it causes a misfire on the cylinder with the short side. The other side is still able to produce enough juice and goes on unaffected.

The way to test the coil is to swap the wires at the coil, see if the misfire moves.

 

[chewy97]

Thanks for the reply I will try that and see what happens.