TO add a few words to this....if you ever drove an older V-8 engined car you may have heard knocking. When using cheap gas (87 octane) you push the gas pedal to the floor to accelerate. When you do this you might hear what sounds like someone KNOCKING on your engine with a hammer. It is a very distinctive sound, it is also a very bad sound. On turbocharged engines it can be deadly to your motor.

The sound is made by the gas in the combustion chamber lighting off before it is supposed to, before the spark plug fires to start the combustion. Your gas engine is starting to act like a diesel engine....VERY BAD.

Knock sensors are essentially sophisticated microphones that listen for knocking. When it hears knocking it it tells the computer, which then adjusts engine timing, fuel mixture, or what ever else it needs to do to get rid of the knocking.

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Nathan Valles, Black 855R, Tint