My experience has been that 9 times out of ten idle problems with 85-91
Vanagons are related to the throttle position switch. This switch lives
under the throttle body and is actuated by a plastic cam. Over the years
the plastic cam will wear to the point that the switch is not being
closed when the throttle is at idle position. You can easily check this
without electrical equipment.

Have the van shut off.
Go to the rear of the van and open the engine bay
Move the throttle lever with your hand slowly to full throttle
At this point you should hear a faint click noise.
Now slowly move the lever back to throttle position with your hand.
Again, right before you are back to idle position your should hear the
exact same click noise.
Move the throttle lever a few times back and forth and you will hear the
noise at full throttle every time. You should hear this noise right
before you get to idle.
If not then your throttle position switch needs to be adjusted. Bentley
tells you how to do this.

If it is adjusted properly then I would suggest testing it with an ohm
meter to be sure that the electrical switch is actually working and has
zero resistance. If it has resistance then it needs to be replaced. If
you find that you need any parts keep me in mind.

Hope this helps,
Ken Wilford
John 3:16
www.vanagain.com

Jeff Hartman wrote:

> Hi, I have been struggling with an unstable idle. It is very cyclic
> and the
> cycles and frequency increase with an electric load (fans etc.) With
> the O2
> sensor and temp sensor replaced, and other tuneup adjustments made,
> the VW
> dealership claims I need a mass airflow sensor. This was determined
> without
> any computer diagnostics. In fact the dealer's service department says
> that
> their new computer testing equipment no longer can test our obsolete
> Vanagons.
>
> I don't have a lot of faith in them, so do you have any ideas of whether
> they are right and what I should test next? I made a cursory review of
> the
> archives over a couple of recent years, without finding this exact
> problem
> described.
> Thanks, Jeff Hartman
> Juneau, Alaska
> 86 2.1 Vanagon
>
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