Knock Detection

[John Dammeyer]

Hi,

I have a question regarding the detection of knocking from too great an
ignition advance and too low an octane fuel.

If I understand the process correctly if the ignition is advanced too far
and the octane level is too low the fuel will burn unevenly creating uneven
pressure wave fronts resulting in the pinging noise.  Backing off on the
timing corrects this for a given RPM/Throttle Position.  The fundamental
frequencies are 5KHz to 11Khz and the Knock Detection devices produce a
voltage out based on the amount of Knock Noise detected.

So here is the question.  For an over advanced engine does the knock only
occur between the time of ignition and Top Dead Center or does it carry over
into the Power Stroke?  Note I am curretnly not interested in Engine knock
due to lean fuel or othe rconditions.  Only knock that shows up when the
ignition is advanced too far. 

>From the ECU perpesctive, I wish to automatically back off, say 5 degrees,
when a cylinder starts pinging and then 8 revolutions later check it again
before starting a gentle move back, a degree at a time, in the direction of
maximum advance.  

Thanks,

John

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