O2 (knock) sensor experts plz

[Jonas K.]

> From: JShadzi at aol.com

> Correct me if I'm wrong here, the knock sensor is a piezo electric device
> that, when sensing 5-10khz resonance in the block, will output a voltage.
> What I want to know is, how much voltage to retard how much timing?  If
> anyone has any of these specs, I would be very interested. 

Well, you misled me with the O2 sensor intro, I was all set, but now I'm a
little un-schooled.  Anyway, I think you're right, the sensor is basically a
piezo-electric microphone. I don't think that it generates a variable voltage
(per se) but that the Control unit interprets the sound for knock and retards
timing until it this sound drops below threshold. Timing is then advanced until
it detects knock. It attempts to hold timing just before knock occurs. 

> I am working on a timing retard device based on boost for NA cars.

Why do you need boost-based timing retard on a NA car... :-) 

Nah, I get your question, and actually Saab used a system called APC in their
late 80's turbo cars (86-93 900, 86-89 9000). Find one in the junkyard and pull
the pieces. 

Here's a great site that shows all the info (apparently Volvo guys use the
system too). Shows pieces you need, location on car, and how to install. 

http://www.teleport.com/~bertram/volvoapc/index.shtml

HTH, 
Jonas