Engine knock is an uncontrolled ignition of the air-fuel mixture in the cylinders, resulting in a “mini-explosion”. During normal combustion of fuel, the flame propagation speed is about 30 m/s, but during detonation, it increases significantly and can already reach 2,000 m/s. A knock sensor is used to prevent and control this phenomenon. The sensor is used to prevent knocking by changing the ignition timing and returning the system to controlled combustion. It is used on injection engines.

1. 3 (E36)
2. 3 Saloon (E36)
3. 3 Coupe (E36)
4. 5 (E34)
5. 5 Saloon (E34)
6. 5 Touring (E34)
7. 3 Convertible (E36)
8. 3 Touring (E36)
9. 5 (E39)
10. 5 Saloon (E39)
11. 7 (E38)
12. 7 Saloon (E38)
13. 5 Touring (E39)
14. Z3 Roadster (E36)
15. 3 Compact (E36)
16. Z3 Coupe (E36)
17. 3 (E46)
18. 3 Saloon (E46)
19. 3 Coupe (E46)
20. 3 Touring (E46)
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The usage of the knock sensor

Strong vibration is transmitted to the engine during knocking combustion. The sensor is designed so that it picks up these vibrations and converts them into an electrical impulse.

The VEMO brand Knock Sensor is installed on the engine block housing. It is usually located between the second and third cylinders. This position of the sensor allows you to adjust more accurately the operation of all cylinders. It is also placed in the area of ​​the most possible propagation of detonation.