Knock alarm

Kevin Vannorsdel kv at us.ibm.com
Tue Dec 16 20:52:03 GMT 1997


Shouldn't you be able to hook up the knock sensor to an ESC module and tap off
the line that goes to the ECM to monitor for knock?

Maybe someone can point out why this wouldn't work-  I haven't really tried it
myself... yet...

________________________________________________
  Kevin Vannorsdel     IBM Arm Electronics Development
    408-256-6492                Tie 276-6492     kv at us.ibm.com




owner-diy_efi at efi332.eng.ohio-state.edu on 12/16/97 07:46:31 AM
Please respond to diy_efi at efi332.eng.ohio-state.edu @ internet
To: diy_efi at efi332.eng.ohio-state.edu @ internet
cc:
Subject: RE: Knock alarm


Tony Cooper wrote:
>
> David Piper wrote:
>
> > Can someone comment on the availability of a knock sensor alarm.  Which
> > sensor would have universal applicability?  How could I fab a circuit to
> > ...
>
> You may have a problem here.
> The sensor sounds about right, but you will have a problem making a
> generic system.
> All engines knock at different frequencies - no 2 engines are the same.
> What you need is
> some intellegence built into the system, something like a DSP would do
> the trick, but even then
> the system may need some 'tweaking' just to get the correct frequency,
> and that would only
> ever work on that engine. Even aging can move the frequency of knock.

Is there somewhere I can go to learn more details about how knock sensors
work? It sounds like they use a resonant sensor, chosen & tuned for the
application, and maybe look for a build-up of oscillation?

I had this idea to use something like a (non-resonant) quartz transducer,
maybe one per cylinder, to get a signal when each cylinder fires. Then I
could monitor the signal under normal conditions, to get a baseline. A
knock should give a stronger, shorter signal, a bit earlier, right? Even if
it needed a DSP, and tuning for each engine, it'd still be useful to me.

I had heard that some aftermarket ignition system had this kind of setup,
but I can't find any info on any such thing.

   TIA,
   Chris Conlon

p.s. Hi, I'm new :)






More information about the Diy_efi mailing list