Date: Mon, 19 Jan 2004 13:15:38 -0500
Reply-To: Jay L Snyder <Jay.L.Snyder@INVISTA.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jay L Snyder <Jay.L.Snyder@INVISTA.COM>
Subject: Re: 85 wbx 1.9 miss at idle
Content-Type: text/plain; charset=us-ascii
Yes, idle speed is initially set by the screw, but it is controlled by the
idle stabilizer. If you turn the idle speed screw while the engine is
running, the stabilizer will try its damnedest to maintain 900 rpm. If you
get too far off, it will start cycling up and down. This is why you need
to set both the idle speed and the timing with the stabilizer by-passed.
(Put your timing light on the crank with and without the stabilizer in
place. You will see the timing jumping around with it on-line. Without
it, the mark stays put.) My point is, with the timing advanced to 5BTDC,
the stabilizer can not as effectively control the idle speed. It is
already advanced 10 degrees from stock. I have seen this over and over.
The idle wanders high and drifts. I was failed at my last inspection for
this reason. (They check idle speed as well as tailpipe emissions.) I knew
my timing was advanced to around 2BTDC. I pulled in the parking lot,
loosened the distributor clamp and turned the distributor. The idle
settled down and I went back through for a re-test. Only ten minutes
later, all passed easily. I checked the timing when I got home and it was
set a about 2 or 3 ATDC.
The Digijet distributor has a vacuum retard built into it for emission
purposes. The retarded timing (5ATDC) causes it to burn hotter and cleaner
at idle. As soon as the throttle is cracked, the retard goes away. Total
advance is in line with the other engines.
All of this is in the Bentley.
Jay
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