Circuit Description

Crankshaft Position (CKP) sensor reluctor (4X) is located on front of crankshaft. CKP sensor will send a pulse on every falling edge of 4X reluctor wheel. A misfire will cause a change in crankshaft speed. The PCM times the interval between each pulse and compares each new interval with the previous one to determine when an excessive change in crankshaft speed has occurred. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes are greater than expected amount, PCM will interpret this as a misfire. PCM continuously calculates crankshaft position from the low and high resolution signals. This information is used to determine which cylinder is misfiring so that the PCM can increment the appropriate misfire counter.