Ford Forums banner

Need HELP solving the wandering misfire!

6.7K views 1 reply 2 participants last post by  gilo  
#1 ·
I have a 4.6 in a Crown Vic P71 that has me baffled on a wandering (literally) misfire. It started out on cylinder #5. I changed all sparkplugs, which it needed and erased the DTC and ran it again. The misfire moved to #8 cylinder. I have checked all the coils and the resistance is within spec on the primary and secondary side. I listened to the injectors and all seem to be working (clicking sound through a stethoscope). I also checked the resistance of the injectors, all are within spec. All resistance tests I listed were done with the engine cold and at normal operating temperature. The coils and injectors are all getting the required voltage at the connectors and the connections are clean. I swapped sparkplug #8 with #7 just in case it was a bad plug from the manufacturer and erased the the DTC. I ran the car again and now the mysterious misfire has moved to cylinder #6. Other than the fact that all of these cylinders are on the same bank, I am at a loss as to what to do next. I don't want to throw parts at this without knowing what the problem is. I do not have the diagnosis manual to go with my service manuals and wiring diagram manual, so I am limited on what to do. Any information would be appreciated. All I have is a DVOM and a code reader, no scan tool, etc. Thanks.