knock sensor

[steve ravet]

GM ECMs use a basic piezoelectric knock sensor.  It's a microphone.  It
goes to what's called ESC, which does some sort of filtering that varies
by application.  Output of the ESC module is an on/off signal to the ECM
that knock is occurring.  On C3 style ECMs the ESC circuitry is a
separate module, about 2" x 2" x .5".  On P4 style ECMs it's on the
module that also holds the EPROM.  In general, some vary.  Bruce did
some work characterizing the response of ESC modules.  If you're using a
GM engine you can probably get an ESC module for it from the junkyard
along with a sensor and be done with it.  Lots of knock sensor info in
the archives also.

--steve

Brian Lewis wrote:
> 
> Hello Everyone,
> 
> I am thinking of adding a knock detection circuit to an engine management
> system that I am developing.  What type of signal conditioning do I need to
> add a GM style sensor? What type of output does this sensor produce and how
> do I determine if detonation has occured? Are there any resources on this
> somewhere? Thanks in advance.
> 
> Brian Lewis