I'm hoping that someone can give me some details about the 1.9 idle
stabilizer.  I have been trying to tune-up and evaluate the engine in
an '84 that I bought for parts.

Does an idle stabilizer contain some type of tachometer?  I understand
that it adjusts the idle speed by adjusting the ignition timing
slightly.  Does it watch the time interval between between ignition
pulses and use some absolute standard to decide if the idle is too
fast or too slow?

Is the timing adjustment always by the same amount, faster or slower,
or does it vary depending on how much the idle is out of adjustment?

When setting the timing on this engine, I have just guessed at the
idle speed, since I don't have any tach.  Afterwards when I reconnect
the idle stabilizer, I can see the timing jumping back and forth.  It
seems to jump between just two positions.  It also seems to spend more
time in one position than the other, depending on how I adjust the
idle speed using the big screw in the throttle body.  It feels to me
that the stabilizer would like me to set the idle speed so that it
spends about the same amount of time in each spot.
Thus it would be able to do more advance or more retard as needed.

Does this make sense or am I all wet?   David are you there?

Larry A.