PIC's and EST on a GM for traction control

Bruce Plecan nacelp at bright.net
Thu Jun 25 02:53:28 GMT 1998


-----Original Message-----
From: Thomas Matthews <Tmatthe1 at worldnet.att.net>
Subject: PIC's and EST on a GM for traction control


>This recent PIC thread has got me really interested in one of my
>"pie in the sky" ideas.... Namely my dream of having traction
>control in my old car... So here's my idea: PIC are available in
>BASIC, so I can handle that (barely), what I would like to do is use
>the PIC to compare inputs from front wheels and the rear wheels,

The fronts live in a brutal world.  gm has all kinds of wheel speed sensors,
but adapting them is the trick.  Also these sensors get
expensive.  Like the s-10 were 50-80 each, plus the pulse ring
in the rotor made them expensive also.

What I did was compare engine speed change to rear wheel speed
change.  For 1+2 gear worked fine.

 and
>when rear RPM is greater than front (by like 5-10 % or so, I could
>see having to play with this too) output a signal to the EST filter
>of a 747 or 165 ECM... Any thoughts?

Recovery of retard too slow, could alter decay rates.
What I did was hide every 7th ign pulse, still wheel spin then every
5th, then 3rd.  That worked fine.

Also tried MSD multi set retard had 3-6-9d chips in it, and turned
various stages on+off so toal was 18d.  the cyl drop was cheapest.
and as good.  By using prime numbers min cyl loading changes.
Sounded real cool when working.  Variable frequency stutter box
if you will.

What does the knock sensor
>output to the filter, and is it easily mimicked by a simple PIC? Any
>thoughts on how fast the ECM could respond to a faked knock signal?
>Or could I tap into the wires from the filter to the ECM and send
>the ECM a direct signal from the PIC?
>Any comments?
>Tom
>




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