Misfire Monitoring: General description

The method of engine misfire detection is based monitoring the crankshaft acceleration. The engine roughness is derived from the differences in the segment period durations that are corrected and compared to engine speed- and load-dependent thresholds.

This method consists of the following main parts:

• data acquisition and adaptation of sensor wheel
• calculation of engine roughness
• comparison with a threshold depending on operating points
• monitoring for extreme road and operating conditions, during which misfire detection should be disabled for a short time to avoid false indications
• statistics and fault processing