System und Verfahren zur Detektion von Fehlzündungen in einem Motor

Exhaust manifold pressure measured by a single gauge-type pressure sensor 126 positioned in the exhaust manifold of an internal combustion engine is used to detect misfires in any cylinder of the engine. The pressure sensor detects the exhaust manifold pressure and feeds a signal to a microcomputer 611 via an analog-to-digital converter 602. A data processing device 606 monitors the pressure waveform created by the data from the sensor 126 to determine if a misfire occurs. Partial or complete misfiring in a cylinder reduces the strength of the pressure pulse for that cylinder, allowing the data processing device to identify the misfire. The data processing device may determine a misfire by comparing the peak sensed pressure for a cylinder with a minimum pressure value derived from the running average peak pressure for all cylinders over a combustion cycle, less a pressure threshold reduction as a function of engine speed and fuel consumption rate. The arrangement may be used in a fuel control system in which the air/fuel ratio is made leaner until misfiring just fails to occur.