[Diy_efi] Crank sensor for knock detection?

[Bevan Weiss]

> Is it possible to use the knock sensor for detecting knock in an engine?
> How to the PCM/ECM's on knock-sensorless engines handle ignition timing
> when knock occurs?
>
> Thanks
>
> Mike

A knock sensor is used to detect knock... however it does so in a weird way.
It is simply an acoustic microphone.  It is mounted into/onto the actual
engine block and when a compression wave passes through the engine block
(from a cylinder knock) and reaches the knock sensor it produces a voltage
(depending on construction).  The voltage (or other) is detected by the ECU
and the ECU responds in an appropriate way, retard timing by 3degress or
similar.  Quite often they will use an analog input, if it exceeds some
particular threshold value the ECU will retard the timing by 3degrees or so,
otherwise it will continue to increase the timing by 0.5degrees every
minute(or so) until it reaches another low level of knock.

The better way, and more revolutionary is ION sense.
http://www.hut.fi/~vvartiov/ion/ion.html

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