Volvo Workshop Manuals
V90 L6-2.9L VIN 96 B6304S (1998)
Powertrain Management > Sensors and Switches - Powertrain Management > Sensors and Switches - Computers and Control Systems > Knock Sensor > Component Information > Locations > Page 1601
Knock Sensor: Description and Operation
The function of the two knock sensors (KS) is to provide the engine control module (ECM) with signals to determine whether the engine is knocking.
The engine control module uses the knock sensor and camshaft position (CMP) sensor signals to identify the cylinder in which knock is present.
The engine management system incorporates two knock sensor, each of which consists of the following components:
Knocking occurs in the combustion chamber when the fuel/air mixture self-combusts. This can occur before or after the spark plug has produced an
This results in an extremely rapid combustion process, characterized by several flame fronts. Pressure increases rapidly and a metallic knocking noise is
Knock in a cylinder produces a certain type of vibration in the cylinder block. The mechanical stresses caused to the piezo-electric crystal in the knock
The knock sensors also detect some normal engine noise. Filtering, amplifying and processing the signal allows the engine control module to recognize
If the knock sensors detect knock above a threshold value, ignition is retarded and the fuel/air mixture is enriched to eliminate knocking.
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