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

ENGINE 113.967 in MODEL 219

ENGINE 113.964 in MODEL 164.1

ENGINE 113.971 in MODEL 251

Fig 1: Identifying Right Knock Sensor 1 And Left Knock Sensor 2

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location

The knock sensors are located at the top of the crankcase below the intake manifold.

Fig 2: Identifying Right Knock Sensor 1 And Left Knock Sensor 2

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Knock sensor signal

Task

Detects combustion knocks at excessive vibrations at the crankcase. Anti-knock control thus corrects the ignition timing for each individual cylinder when the engine is warmed up.

Fig 3: Knock Sensor Signal Pattern

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Design

The knock sensors work according to the piezo ceramic principle. The screened cables are connected directly to the knock sensors.

Function

Any vibrations which occur are converted with the aid of the piezo ceramic into electrical signals.

The noise signal is modulated to a DC voltage from 0.13 V to 4.7 V for transmission to the ME control unit.

Piezoelectric effect: If a mechanical force acts on a crystal, electrical voltages are produced.

Knock sensor signals can also indicate engine damage (e.g. increased engine noise due to widened piston grooves).