DIY_EFI Digest V5 #17:Knock sensor, etc.

[Carter Shore]

Thanks Bruce, 
I had not thought about noise contribution from mech
valvetrain. And of course, IGOR will allow some very
accurate knock detection, but I didn't think it was
available yet.
Here's a Q, do you know how/if GM systems handle false
KS trigger, vs RPM?
For example, say an ECU has a KS sensitive to say,
4,000 Hz. Frequency of bormal internal noise from the
motor varies with RPM, so at some RPM, it will also
create 4,000 Hz noise that would trigger the KS. Does
the code ignore KS at certain RPM?

Bill, I looked at your site, it's good stuff. I had
seen the app note, was looking for a simpler (lazy and
cheap) way to do it. Plus, if my motor's knock
signature matched a stock unit, I could just use off
the shelf stuff. 

I downloaded your knocking WAV file, to play with.
I did not see a display where you had examined the
signal in 'line' or 'bar' mode. This would show up any
resonant freq and harmonics as spikes, much easier to
pick out specific components of a sound. Requires a
sound card in PC, so I'll have to wait 'till I get
home to try it.

Does anyone have access to a supply of different KS?
It might be useful to document the resonant freq and
output levels of various stock parts. Just need a
signal generator and a scope (or Spectrograph). I'll
volunteer to run the tests, if we can work out a way
to ship the units. Some details to hash out if any
interest.

Thanks all,

Carter
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