Date:         Tue, 4 Feb 97 08:56:48 -0600
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Rocko Flamefart <-@--.-->
Subject:      '83-'85 hunting idle

Dan (another Dan) had asked about his hunting idle on a Digijet system...  i
remember experiencing fits of that when the basic idle setting would get out
of whack.

the idle system is a balance between many things.  the basic throttle plate
setting, the idle screw setting, the idle mixture setting, the actions of
the black box idle stabilizer (which regulates speed thru timing changes),
and the throttle switches.  all must be in balance and adjusted in the
proper sequence per Bentley.  this is one time where following the manual
really does pay off.

but screw the book!  :)

a hunting idle can sometime be remedied by slowly adjusting the idle speed
screw on the throttle body-- that big round screw canted up at a 45 degree
angle.  what you are trying to achieve is a match between the preprogramed
speed the electronic idle stabilizer wants to run the engine at versus the
amount of bypass air the throttle body is allowing.  when *mismatched* the
electronic portion changes the timing to lower or raise the idle... but it
can overshoot and thus tries to correct itself, hence the hunting.  when
*matched* the stabilizer has very little work to do and the system does not
swing high and low.

you can hear the changes in *timing* when the idle speed screw is turned.
the engine will smooth out or 'work' against the ignition point yet the
actual speed changes little due to the timing advance/retard.  this requires
a delicate hand and yes, you can really screw up the basic setting to the
point where you don't know where the hell you are.  and for gosh sakes don't
mess with the throttle plate stop screw unless you are going to set it by
the book with a feeler gauge.  then it is time to go back to Bentley and do
it by the book.  but for the brave of heart, it may be a quick and dirty way
to relieve hunting.

-dan