513 Misfiring, Cylinder 6: Function

To detect misfiring, the drop in engine speed which results when there is a partial lack of combustion at one or more cylinder is evaluated.

A distinction is made between emission relevant misfiring after start-up, emission relevant misfiring during the journey and misfiring which is damaging to the TWC. See DTC Identification (2 Of 6)  table.

The engine speed is measured with an inductive sensor that is located above the ring gear on the flywheel. The ring gear is divided into three segments. For detection the time between two segments is measured and the difference calculated. This difference is corrected by a mean value that is developed over several segments, to compensate for engine speed fluctuations caused by driving conditions. If the corrected value is above a specified threshold value which is dependent on engine speed and engine load, a misfire is detected. See Function Description of Sub-systems .