Crankshaft Relearn

In order to correctly detect misfires, the ECM must learn the variation between the 58 crankshaft notches. This notch learn variation is done automatically by the ECM for 24 ranges determined by engine speed and load.

The ECM continuously updates the notch variation whenever misfire is enabled and no misfires exist in the particular range. The ECM will take about 20-30 seconds to learn the notch variation for each speed/load range. If a speed/load range has not been learned, misfire diagnostics will still be enabled, but misfire criteria will be relaxed.