Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position (CKP) sensor to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. The camshaft position (CMP) sensor is used to identify which cylinder is misfiring if a majority of the misfire occurs on the same cylinder. If there is a camshaft position (CMP) sensor error, misfire will be detected but the specific cylinder cannot be identified.