Flex Plate: Description and Operation

Flywheel:
In connection with the automatic transmission, the flywheel is of a one-piece design and made of steel. A hydraulically dampened dual mass flywheel (ZOOMS) is used on manual transmission vehicles.

As on the M73 engine, the increment gearing for the crankshaft sensor is located on the flywheel for both variants. The inductive pulse generator is mounted in the transmission/clutch bell housing. The new installation location for the increment wheel on the flywheel now makes it possible for the DME control unit to detect misfiring.

On the previous engines, the increment wheel was mounted radially dampened by means of a vulcanized rubber element on the torsional vibration absorber. With this arrangement, it would not be possible to detect irregularities in engine speed.

On the flywheel, the increment wheel is connected rigidly to the crankshaft without a damping element.

In this way, irregularities in engine speed, caused by misfiring for example. are transmitted directly to the increment wheel. In addition to the engine speed and reference mark, misfiring caused by faults in the ignition or fuel injection systems can now be detected with the inductive pulse generator. Misfiring detection is a requirement laid down in OBD II (US).