Looking for guidance with a cylinder 5 misfire issue. Often it will throw a multiple cylinder misfire after throwing 2 or more cylinder 5’s. It seems to only happen when holding somewhere around 2,800-3,200 RPM for steady amount of time, say going up a long steep hill or passing someone on the interstate. Runs, idles, and starts great other than this issue.

I have installed new spark plugs, new wires, a new distributor cap, and a new distributor rotor. Could this be a fuel issue? It has a new fuel pump that is a year or so old, and a new fuel filter that is around 4 months old. Hoping it isn’t an issue with my spider injector.

 

How does the truck run?

You have a P0305 code or you see misfires on a scanner in live data?

Have you adjusted CMP retard?

Have you performed a fuel pressure leak down test?


George

 

I’d definitely check fuel pressure in it first

 

The truck runs great, I don’t even notice the misfire until it throws a check engine light.

I am getting a P0305 code from a scanner.

I have also begun to get cylinder 4 misfire alongside the multiple cylinder and cylinder 5.

I will check fuel pressure next and go from there.

Thanks!

 

Fuel pressure is a great start but you will also need to get CMP retard in spec so you don't start chasing misfire ghosts.


George