Theory Of Operation

For proper engine control and combustion stability the Camshaft and Crankshaft positions must be aligned and known such that fuel injection and spark timing can be introduced at the Intended piston and intake/exhaust valve positions. During vehicle manufacturing, at end of line, or if a Cam/Crank Relearn is performed, the system learns the difference between the Camshaft and Crankshaft position in terms of engine degrees and stores it in the EEPROM. During drive cycles, the actual Cam/Crank position is monitored and compared to the stored value in the EEPROM. If the PCM detects a difference that exceeds a calibrated threshold, a fault is detected.