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Component description for the knock sensor - GF07.04-P-6030MCC

ENGINE 132.9 in MODEL 451.3 /4 

Fig 1: Identifying Knock Sensor
G07077257Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location 

The knock sensor is located on the engine crankcase under the exhaust manifold.

Task 

The knock detects vibrations which are emitted by the cylinders and transmits these in the form of an electrical signal to the ME-SFI [ME] control unit (N3/10).

IMPORTANT In the event of failure of the knock sensor, the ignition performance map for low quality fuels or fuels with a low octane rating is used by the ME control unit.

Design 

The knock sensor consists of:

Function 

The knock sensor is screwed through the thrust sleeve to the crankcase. The vibrations which are coming from the individual combustion chambers are transmitted by the seismic ground to the piezoceramic perforated disc. The piezoceramic generates an electrical voltage signal and passes this on to the ME-SFI [ME] control unit.

IMPORTANT The piezoceramic consists of crystals on whose surface an electrical voltage is generated through deformation.