Checking the condition and replacing the knock sensor

Knock sensors respond to an increase in engine vibration, usually caused by detonation of the air/fuel mixture. Based on the information received from the sensor, the PCM corrects the ignition timing, trying to maintain it at the highest possible level, guaranteeing sufficient engine efficiency. The sensor generates an AC signal whose amplitude increases in proportion to the level of vibrations. To compensate for detonations, the PCM, if necessary, issues a command for shifting the ignition timing in the direction of deceleration. On models 1993 and 1994 issue The sensor is mounted on the right side of the engine, directly below the exhaust manifold. On models since 1995, no. The sensor is placed under the intake manifold.

Examination

Disconnect wiring from sensor. Measure the resistance between the two terminals of the sensor connector - the ohmmeter should register the presence of conductivity, otherwise replace the sensor.

Note. The electrical resistance of the knock sensor is very high, use an ohmmeter whose connecting wiring is rated at least 10 mΩ.

Replacement

Models 1993 and 1994 issue

Attention! Wait until the engine has completely cooled down before proceeding with the procedure.

1. Empty the cooling system (see chapter Settings and ongoing maintenance).

2. Jack up the car and put it on stands

3. Disconnect the electrical wiring from the knock sensor and release the harness from the intermediate clamps.

4. Remove the sensor from the engine block.

5. Installation is carried out in the reverse order.

6. Don't forget to charge the cooling system (see chapter Settings and ongoing maintenance).

Models since 1995 vol.

1. Remove both (top and bottom) intake pipe sections (see part SOHC engines Head Engine).

2. Disconnect the wiring from the sensor.



3. Turn out a fixing bolt and remove the gauge from the block of the engine.

4. Installation is carried out in the reverse order.

5. Reinstall intake manifold (see part SOHC engines Head Engine).