Knock Sensor Control

The knock sensors of the M73 engine are identical to those used on other BMW engines. The use of knock sensors allows the DME to constantly maintain the optimum ignition timing curve for all engine operating conditions. If detonation occurs, the signal from the sensors allows the DME to retard the ignition timing to prevent engine damage.

Each DME control module monitors detonation through two knock sensors which are mounted on the cylinder head close to the combustion chamber.

This configuration is similar to the M3.3.1 system using two sensors per 6 combustion chambers. The DME recognizes the knock location based on the ignition firing sequence and cylinder ID sensor input.