Fault handling and misfire statistics (%DMDMIL): Notes
Each combustion, apart from those deactivated, has to be checked for misfire since misfires can be distributed arbitrarily (see Fig 1). A fault handling action will, however, only take place if specific percentage misfire levels are exceeded.
The different effects of misfire (emission impairment and catalyst damage) are handled separately in two branches of the function.
During the fault entry a distinction is made as to whether it is an emissions relevant fault after start, during the driving cycle, or whether it is a catalyst damaging fault. Furthermore a cylinder identification of the misfiring cylinder is performed. At catalyst damaging misfire rates it is possible to switch off the injection of the corresponding cylinder to protect the catalyst. If more than one cylinder is misfiring, both the cylinder-individual fault entry and a "multiple misfiring" entry will be carried out (see Figure).
Any pending fault code is erased when monitoring in the next driving cycle encounters similar conditions without detecting a malfunction.