Gary Z

I would like to know how the CKP variation learn procedure works. I know that CKP error values are stored in the PCM and that these values must be relearned if the PCM or CKP sensor are replaced. I know that the CKP sensor generates a position code every 15 degrees of crankshaft rotation. It is obviously easy to determine relative variations of individual sector periods from the average but I wouldn’t think these are significant. I assume that the most important error is the absolute difference between the 0 degree CKP signal and true cylinder 1 TDC. I know that the relearn procedure involves running the unloaded engine up to speed. My guess is that the relearn procedure varies the timing to somehow determine TDC but, as I say, that is only a guess. If anyone were willing to share knowledge of this subject I would very much appreciate it.

Thanks, Gary