Guys, in chasing down a couple of cylinder misfire codes I changed all the usual suspects...plugs, wires , cap rotor on a newly acquired clunker. Question is , what parameters, or inputs, are provided to the ECU and logic used when the ECU posts misfire codes. I am sure these cylinders are firing at some rpm, but have not determined the level of efficiency of the cylinders. May have burnt/damaged valves, broken rings, bad cam lobes or maybe ineffienct fuel delivery to these cylinders. Just wish to learn how the system works........