Inventors:
Suresh M. Mangrulkar - Farmington Hills MI
John W. Piatak - Livonia MI
Assignee:
Ford Motor Company - Dearborn MI
International Classification:
G01M 1500
Abstract:
An adaptive method of detecting a misfiring cylinder in a spark-ignited internal combustion engine during substantially all engine operating conditions, including most no-load operation. The method includes the step of normalizing an engine acceleration-independent and engine speed-independent power cycle time differential signal for a particular cylinder of the engine, obtained from consecutive power cycle time periods of an engine cycle, utilizing a calibration parameter stored in the memory for the particular cylinder, to obtain a normalized power cycle time differential signal for the particular cylinder. The method also includes the step of comparing the normalized power cycle time differential signal to a misfire threshold signal stored in the memory to determine if the cylinder is misfiring. Preferably, the misfire threshold signal is based on at least one engine operating parameter. The method also includes the step of adaptively modifying the calibration parameter stored in the memory based on the comparison.