Monitoring Process

A new function for pre-filtering of sensor wheel segment duration signal is introduced to Sephia in order to enlarge the misfire monitoring range. The sensor wheel segment duration is pre-filtered by this function and then the filtered value is used to calculate the engine roughness which is compared with the reference value to detect misfiring. With this function, it is possible to eliminate the influence of the crankshaft-synchronous oscillations on the detection of misfire. These oscillations can be caused by sensor wheel tolerance or crankshaft torsional vibration. The misfire monitoring of Sephia covers nearly the full range of engine operation in case of random or continuous misfire, and for symmetrical misfire.