Knock Sensors (KS) - Monitor The Frequency When Detonation Occurs
Knock Sensors (KS) – Monitor The Frequency When Detonation Occurs

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Engine Spark Knock – That Annoying Knocking, Pinging Or Rattling Sound

Engine Knocking – Pinging – Rattling Noise – Common Causes


So, The knock sensors job is to monitor the engine for any signs of detonation. Consequently, Detonation is the premature ignition of the air/fuel mixture. Furthermore, Detonation produces a distinctly mechanical knocking sound. But, Is usually detected at higher engine speeds or a sudden increase in engine load.

So, To improve engine efficiency, the (PCM) keeps the ignition timing as far advanced as possible. Based on the current operating conditions such as engine speed/load, throttle position, and vehicle speed. However, Any increase in the engine speed/load from current conditions will cause the air/fuel mixture to ignite prematurely.

Consequently, Producing the same knocking sound as detonation. So, To prevent detonation, The knock sensor monitors the frequency at which normal detonation occurs. Also, Providing the (PCM) with a continuous live data stream, that allows the (PCM) to control the ignition timing.

But, If the knock sensor detects a change in that frequency, it will generate a new signal voltage. Consequently, That signal voltage is based on the changed frequency. Which the (PCM) then interprets as detonation.

So, To correct this condition, the (PCM) then retards the ignition timing. But, Only when the detonation frequency matches a wave amplitude, that is based on a pre-programmed value.

So, The advantage of this is that the (PCM) can always keep the ignition timing advanced. As a result, Suitable for any given set of engine operating conditions. Therefore, Increasing engine efficiency and fuel economy, while reducing emissions. Finally, A defective knock sensor has a direct bearing on engine operation and efficiency.

Knock Sensors Failure Symptoms:

  • 1) Engine Warning Light
  • 2) Loud Sounds
  • 3) Bad Fuel Mileage
  • 4) Poor Acceleration
  • 5) Poor Engine Performance

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