I have a 2001 Ram Sport Quad 5.9 magnum. Okay, so I got this p0308 misfire code, I replaced plenum and lower intake gaskets, #8 injector, new wires, plugs, distributor cap, rotor. 2 compression tests by the book and passed. I heard that sometimes the engine control box fuse can go bad and cause it. I replaced both the 30 amp and 20 amp engine control fuses, immediately the light went out. Next day light comes back, I pull the engine control 20 amp box fuse out and push it back in, I hear a click, light out again? I'm thinking possible culprits could be: A bad or shorted pickup coil aka Cam Position Sensor in the distributor, maybe an O2 sensor? I do believe it runs rich when it acts up. Or, a bad PCM. Anybody had similar electrical issue. I'm going crazy with this crap.

 

what were your numbers on the compression test?

Plug a noid light in to that injector connector, and make sure it is pulsing.

Is it an intermittent miss? or is it a dead cylinder? (no fire at all)

 

Injector is pulsing, didn't get individual numbers but they all showed strong,(had a trusted mechanic do it), he said.

 

Sounds like the same trouble I have. 2002 1500SLT 4x4 5.9- Replaced plugs, wires, dis. cap and rotor, filters.. Still get a #8 misfire when I start the truck, after about 30 seconds it runs fine. Thinking it might be an O2, cat, or injector. Don't know what else it could be. My truck only has 33K miles on it and when I looked down the intake I didn't see any oil pooling.

 

How's your fuel pressure? (though, if that were the issue, I would be more inclined to think cylinder 2 would be the problematic one.....)

Does it always miss? or is it intermittent?

 

It sprayed like hell off the rail, when I removed the old one, lol.