m54 engine - BMWClub.lv

MISFIRE DETECTIONAs part of the CARB/OBD regulations the engine control module must determine if misfireis occurring and also identify the specific cylinder(s) and the severity of the misfire event,and whether it is emissions relevant or catalyst damaging. In order to accomplish thesetasks the control module monitors the crankshaft for acceleration losses during firing segmentsof each cylinder based on firing order.Misfire Detection Example: M54 (6 Cyl.) with Siemens SystemThe misfire/engine roughness calculation is derived from the differences in the period duration(T) of individual increment gear segments. Each segment period consist of an angularrange of 120° crank angle that starts 78° before Top Dead Center (TDC).If the expected period duration is greater than the permissible value a misfire fault for theparticular cylinder is stored in the fault memory of the ECM. Depending on the level of misfirerate measured the control unit will illuminate the "Service Engine Soon" light, may cutofffuel to the particular cylinder and may switch lambda operation to open-loop. All misfirefaults are weighted to determine if the misfire is emissions relevant or catalyst damaging._________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________29M54engMS43/ST039/3/17/00