Date:         Wed, 3 Jan 2001 16:15:36 EST
Reply-To:     Wolfvan88@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Lilley <Wolfvan88@AOL.COM>
Subject:      Clues to the cold start/running problem- my test
Content-Type: multipart/alternative;

Well, I finally had some time to test my thinking about the cold
start/running problem.

I put my old idle control module back in and started the van to see if the
problem would surface.  Cranked it and it started fine and ran fine with no
problems. Revved the engine OK cold and it would idle and not die (It might
just mean that my control unit was OK after all, but it did smell burnt...).

Waited about 4 hours, to make sure it was cold, and then this time unplugged
the throttle switch (to simulate a misadjusted throttle switch).

Well, it started fine, but when I pressed the gas it stumbled would not rev
smoothly.  I would press the gas and then let off and it would die.  Each
time it took a few cranks longer to start.

I took it for a short test drive down the block.  I was in first and it lost
power when I let up on the gas and then pressed it to accelerate back up in
first.

The idle speed was bouncing between 800 to 1100 after it had warmed a few
minutes.

It seems that when the throttle switch is out of adjustment, the cold
start/running problem surfaces.  While cold, the engine cannot run on the
amount of fuel/air mixture the ECU thinks the engine needs (it thinks the
engine is revving higher and not idling. The mixture is different for idling
Vs running.  Vacuum changes, when pressing the gas pedal, increase the fuel
pressure and the mixture).  And therefore the loss of power feeling is due to
lack of enough mixture to support a COLD engine idling.  As the engine warms,
the fuel can then support the idling.

Other problems with the FI can make this problem worse or mask it.

I would recommend all who read this to check there throttle switch(es) and
listen for the click.  If you do not hear it adjust it until you do.

Robert

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