Knock sensor (KS) (some models only) (Peugeot Eurovans 806)

Since detonation can occur at different times in each individual cylinder, the MM 8P uses a detonation control microprocessor (in the electronic control unit), to indicate the specific cylinder or cylinders in which detonation occurs. Knock sensor (see illustration 12.12) installed on the cylinder block. The sensor converts the signal into a voltage signal that is returned to the knock control unit for evaluation and replay of the action. The detonation frequency is in the 15 kHz frequency range.

Knock Sensor (KS) Voltage Values Note: The knock sensor signal will provide a maximum voltage amplitude of approximately 1.0 volts.

Terminal numbers

See Figure 12.6

Knock sensor frequency

Approximately 15 kHz.

Influence of external factors

• Incorrect setting of the main ignition timing angle
• Low quality gasoline
• Ignition system malfunction
• Cooling system malfunction
• Formation of carbon deposits in cylinders

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Checking the knock sensor (general check)

1. Inspect the knock sensor multi-pin connector for signs of corrosion or damage.

2. Make sure the connector terminal pins are properly installed and have good contact with the knock sensor multi-pin connector.

Knock sensor testing procedure

Note: If the engine does not have timing marks, then the piston of cylinder No. 1 must be set to the TDC position and the corresponding marking must be made on the housing and front pulley in order to perform the following procedure.

1. Connect the inductive timing light probe to the high tension wire of cylinder No. 1.

2. Allow the engine to idle.

3. Gently tap the engine block in the area of cylinder No. 1.

4. The ignition timing should be noticeably delayed.

5. Move the inductive stroboscope probe to cylinder No. 4.

6. Gently tap the engine block in the area of cylinder No. 4.

7. The ignition timing should be noticeably delayed.

Knock sensor testing procedure (Oscilloscope)

1. Connect the low voltage probe of the oscilloscope to terminal No. 2 of the knock sensor signal wire.

2. Gently tap the engine block in the area of one of the cylinders.

3. The oscilloscope should display the waveform of the knock sensor signal (see illustration 12.13).





4. Repeat the procedure for other cylinders.