The engine can be damaged as a result of detonation that occurs when the fuel mixture is burned. High compression ratios, which improve the fuel efficiency of the engine and change the quality of the fuel used, increase the tendency of the engine to knock, i.e. explosive combustion of the fuel mixture in the engine cylinders. The knock sensor responds to high-frequency oscillations of the cylinder block and transforms them into electrical signals, the magnitude of which increases with increasing knock. Based on these signals, the engine control unit shifts the ignition timing to the side of delay, for a certain number of cycles, after which it gradually returns to its original position. The knock sensor is located on the rear side of the cylinder block, directly under the head of the block.
Replace knock sensors as follows:
- turn off the ignition and disconnect the wire «masses» from the storage battery;
- drain the coolant from the cooling system;
- on models before 2001 and on all-wheel drive models, remove the intake manifold;
- on front-wheel drive models before 2001, raise the front of the car and secure it on supports;
Pic. 7.19. Knock sensor on models up to 2001: 1 - electrical connector; 2 - knock sensor
Pic. 7.20. Knock sensor on models from 2001: 1 - electrical connector; 2 - knock sensor
- disconnect the electrical connector, unscrew and remove the knock sensor (pic. 7.19, 7.20).
When installing the knock sensor, apply a layer of sealant to its threads.
Screw in the sensor and tighten it to 44 Nm.
Note. The threads of the new sensor are already sealed with sealant.
Further installation is carried out in the reverse order of removal. After installing the sensor, fill the coolant into the cooling system.