Knock Sensor
The sensor is located on the engine block, below the intake pipe between cylinders 2 and 3. The resonance frequency of the piezo sensor is 8 kHz, which corresponds to the engine knock frequency.
Mechanical vibration in the engine block is continually converted by the sensor into an electric signal (alternating voltage). If there is a considerable increase in the output voltage level, the sensor signals engine knock to the knock module in the control unit.
For diagnostic reasons, the control unit sets a constant voltage of approx. 2.5 volts to the knock sensor.
If the constant voltage level changes due to a lead short circuit or interruption, the system switches over to the 91 RON characteristic map.
In addition, the firing angle is retarded by 5°CA in the interests of safety.
| This prevents the risk of damage to the engine. | |||
|---|---|---|---|
| .P. F0322.tif | 9 | 7,5 | tiff;; |
| Engine | Part no. | Knock frequency | |
| X 14 XE / X 16 XE | 10 456 190 | 8000 Hz. |