Knock sensor

Knock sensor

I had connect the knock sensor up to an oscilloscope, in the next picture waveform of knock sensor.

Vibration the pizoelectric element generate a voltage . In this picture waveform the output voltage from the knock sensor , highest is time , arrow A shows strong , arrow B shows weak .

Knock sensor detected engine knock sends voltage signal to the ECM. The ECM uses the knock sensor signal to control timing. Engine occurs within specific frequncy range.

The knock sensor located in the engine block, cylender head or intake mainfold it's tune to detect that frequncy. Inside the knock sensor is pizoelectrec element , Pizoelectronic generate voltage, a voltage when pressure or vibrate is applayed to them .
The pizoelectronic element in the knock sensor is tuned to the engine knock frequncy.

There is vidio of waveform knock sensor , when vibrate the sensor that creat voltage output.