Circuit Description

Each knock sensor is fitted to the right bank and left bank of the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which generates a voltage when it becomes deformed. The piezoelectric element sends a signal to the ECM, when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.

HINT:

• Bank 1 refers to the bank that includes cylinder No. 1.
• Bank 2 refers the bank that does not include cylinder No. 1.

Reference: INSPECTION USING OSCILLOSCOPE 

• With the engine racing (4,000 RPM), check the waveform between terminals KNK1 and KNK2 of the ECM connector and body ground.

HINT:

The correct waveform is as shown.

• Spread the time on the horizontal axis, and confirm that period of the wave is 0.13 msec. (Normal mode vibration frequency of knock sensor: 8.1 kHz)

HINT:

If normal mode vibration frequency is not 8.1 kHz, the sensor has malfunction.