Knock Sensing with MACXXX ECU...

[Gerard <gerard@poboxes.com>]

Hi!

Dumb question ahead. Avoid if not interested at all. :)

Just sitting here inbetween part collecting and fixing of the 200
as usual, and I'm thinking again about engine management computers
as a "hobby". :) EFI332 sounds good, most of the stuff can be
done on the 5 cylinder MC (excluding easy fuel rail building
and injector placing), but one thing that has bugged me is the
knock sensing bits. Anyone electronically and technically
inclined have insights into how the MACXXX ECUs do the knock
sensing? Is it simply the conditioning circuitry listening to the
knock sensor/microphone and filtering out all frequencies below
the "knock" and then outputing a "high signal" when the frequency
of knock is heard? What would be the "knock frequency" of the
MC motor? Like a high-pass filter/crossover. Or am I as usual on
the wrong track here and should just rip open a Hitachi ECU and
"super-reverse-engineer" from the knock input to the lines to the
CPU top half? :)

Blah blah blah yadda yadda yadda should be doing work blah blah
bored.

G. (erratically idling mind cooking up dumb ideas)

PS: no way I'm doing the electronics, that's up to a friend who is
    keen on it.