Date:         Fri, 9 Jul 2010 01:03:32 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: engine revving at idle
Comments: To: Mark <mbrush@GMAIL.COM>
In-Reply-To:  <AANLkTimoaA0UaMQrBFRI5CnoGOp4cehxL6aNJWyxu9gt@mail.gmail.c om>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 09:02 PM 7/8/2010 Thursday, Mark wrote:
>but I can't get any continuity when I "slowly" bring back into place
>
>So what now?  How do I fix this?  Is it just a matter of adjusting the
>throttle valve?  Why does it get continuity when it snaps back into place,
>but not when I slowly bring it back?

Fix it by adjusting it the way the book says, so that it closes when
you slowly close the throttle.

The reason it closes when you let the throttle snap shut smartly is
that all the little resistances in the entire system from pedal to
throttle plate are overcome by inertia, and the cam follower that
operates the switch itself also is driven by inertia.  The switch is
an "over-center" type so that it will snap closed and stay there even
though the cam follower retracts slightly.

Very likely you have a worn throttle body, as somebody pointed out
above.  VW designed it poorly and when it wears it makes the
closed-throttle switch setting more tricky.

This must be correct or the engine will not idle properly, so fix
it.  However I don't think it's the cause of your very high idle after warm-up.

To watch the operation of the switch from the driver's seat, run a
couple wires up from the switch wiring and connect a small yellow LED
across them.  At closed and wide-open throttle the LED should be off
or dim; at all other throttle positions it should be bright.

Once the symptom is happening and supposing that the LED stays
bright, pull out of traffic and check to see if the throttle is stuck
partly open.

Yours,
David