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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


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