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Cylinder #6 not firing

3148 Views 12 Replies 4 Participants Last post by  Bill1013
My PSD has a miss. Took the valve covers off to determine which cylinder wasn't firing. #6 cylinder no change in the sound of the engine when I pull the injector wire off. The rest of them caused the engine to stumble even more when I pulled the injector wire off. I replaced the under valve cover harness on both sides with the newer style with integrated harness. Then ohmed the injector and that was good. Checked resistance from #6 all the way to the ECM with no breaks in the wire. Now I'm stumped. The rig only has 102K miles on it (motorhome) so I'm leaning away from a bad injector. Any thoughts?
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I'm not familiar with measuring the armature gap. What's that? I don't recall if it was spitting oil. What would it tell me if it isn't. My next step is to swap injectors but was holding off on that because of the pain in trying to suck the oil out of the cylinders.
Update: I've got oil coming from every oil spout (including #6) but #6 continues to be the only cylinder that doesn't cause the engine to stumble when I unhook the wire. What does this mean?
Thanks for the responses guys. It turn out to be a wiring issue. I swapped a couple of injectors and the misfire continues to be at #6. I can't explain the earlier test where I checked continuity all the way back to the ECM. My next step is to swap out the UVCH plug. I just hate to do that because it creates a lot of splices.
Yes, I meant splice in a new plug on the outside which I did and it didn't fix the problem. Is there a way to tell if the ECM is sending a signal to the injector without doing a buzz test? I don't have any fancy tools like that.
Alright, finally found the problem. Hole in the #6 piston. Have cracks in all of the other pistons. #6 is the one that burned through first. Time for a rebuild. BTW, pulling a PSD out of a Class C motorhome (van cab) wasn't as bad as I thought.


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