1.3 Misfire Detection: Notes

P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308 (MDmin, MDmax, MDnpl, MD00min...MD07min, MD00max...MD07max, MD00npl...MD07npl) 

The misfire monitor is designed to detect combustion misfire by evaluating engine (crankshaft) speed fluctuations. The entire function for misfire detection consists of various sub-functions which together guarantee complete detection of misfire according to legislative requirements (graphical description see Fig 1).

The diagnostic starts with the calculation of a segment duration (tsk) from the crankshaft signal, and correcting it with a self-learning sensor wheel adaptation (fuel-off adaptation). Engine speed fluctuation values are then calculated and again corrected by an extended adaptation (fuel-on adaptation). The misfires detected by the individual methods luts, dluts and fluts are linked together and further processed in the fault code management. The fault code management determines appropriate fault code reporting and MIL action if required.