What sort of signal is the knock sensor?

[rr]

Try a rapidly changing frequency, see if that trips a count.

BobR.

Each milli-sec is a 'count' at the ecm. . .You can get them strung
together.

Don.F.Broadus at ucm.com wrote:

> I 'm using a 1.5 inch threaded pipe (1/4 inch NPT)  I removed the pipe and
> butted the  sensors together. This did not provide enough coupling to
> trigger the ESC. I don't have any more NPT pipe so  I then filled the pipe
> with ultrasonic coupling fluid to see if the cavity was resonating. 6KHz was
> still the sweet spot although a little quieter now.  I believe each det
> sensor being a peizo transducer has been tuned like a quartz crystal at a
> certain freq. (6KHZ)  By using two  DR 562 sensors they both are in
> resonance at 6 KHZ. I need to find more det sensors as I only have one of
> certain types right now. The DR 562 is by far the easiest to find being used
> on V8's , V6's four's carbed and injected. I'm looking for Quad  4 sensors
> to test believing that they will be tuned  higher to mask the bucket tappets
> and chain noise.
>                                                  Don
>
> > -----Original Message-----
> > From: jsg at donet.com [SMTP:jsg at donet.com]
> > Sent: Tuesday, November 23, 1999 3:59 PM
> > To:   gmecm at efi332.eng.ohio-state.edu
> > Subject:      Re: What sort of signal is the knock sensor?
> >
> > | By using the output of a HP3324A function generator connected to  DR 562
> > | knock sensor coupled with a 1/4 pipe to another DR 562 knock sensor I
> > was
> > | able to track the freq. curve of the sensor. The sensor responds to
> >
> > <delete>
> >
> > | with a scope the DR 562 sweet spot was 6KHZ. A loud tone could be heard
> > at
> > | 6KHZ indicating resonance.  7-10KHZ had good outputs. The voltage
> > dropped
> > | off at 12 KHZ . An output was observed up to 50KHZ very small amplitude
> > 4
> >
> > Don, is this a resonance of your test setup or of the sensor? (i.e.,
> > if you double or halve the length of pipe, does it stay the same?)
> >
> > john gwynne