Po304

[holorinhal]

My Check engine light came on and I got a trouble code of PO304 which is #4 cylinder missfire. What else besides plugs, wires and coil ,could cause the missfire? Thank's ...Hal

[a98gtp4u]

bad injector, compression, dropped valve. start on the cheapest thing 1st and then go up. prob something simple. i also had a cylinder 4 misfire and it was a cracked plug.

[blueguy]

You'd know if the valve dropped...that would be a bit WORSE than a little misfire.

Go back and recheck your work...then check it again for good measure. I say remove the coils and clean them...then clean the ICM (bracket the coils sit on)...then seafoam it IMO.