[sci.electronics] Car ECMs: try the analog approach!

hobbit@vaxeline.ftp.com (*Hobbit*) (04/26/91)

These ECMs tend to rely on analog inputs of one sort or another to sniff out
what's going on in the engine.  For instance, O2 sensor, crank angle, ambient
temp, airflow.  The airflow sensors are sometimes the hot-wire type mounted
in the incoming air throat after the filter.  On my Isuzu, I installed a
little pot to add a voltage into the airflow sensor input, and now have a
rich/lean mixture control.  I haven't researched diddling the timing on the
fly yet, but I'm reasonably certain a simple pulse-delay circuit hung off
the crank-angle sensor would take care of this.

This was a secondary choice to what I *really* wanted, but when I went car-
shopping last year and kept saying "carburetor?" and getting laughed at a
lot by dealers, I figured it was time to learn something about how the ECM
I wound up with works.  What a pain in the ass, though.

_H*