I don't know if it uses a time or count base but I do understand how it
operates. Idle stabilizer is a poor description. It is really an idle speed
booster. When the engine speed goes below a certain limit it begins to
advance the timing to bring the speed back up. There are two versions, green
and black. The black begins to work at a higher set point ~750 rpm from
experience. This is way below where you want to be anyway. When doing the
basic settings/tune-up it should be bypassed. AC and power steering should
have idle boost solenoids so this device really only helps to compensate for
electrical loads and O2 sensor variations.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Larry Alofs
Sent: Sunday, September 16, 2012 4:46 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Idle stabilizer question--1.9

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.