I'm having the same problem with my '88.
In my case, the replacement of the idle stabilization control with a new
one caused the idle to go high.
I cleaned out my valve and it is also buzzing away.

If I use my old (bad) idle stabilization unit, it idles correctly.
Interestingly, I replaced the voltage regulator transistor on my "bad"
unit and when I plugged the "repaired"  one in, the idle went up again
(but not as much as with the new "D" unit.)

So I'm suspecting that the high idle is caused by something else.
Its almost like the motor thinks the A/C or Power steering switch is on,
and is trying to bump up the idle accordingly.
The other interesting thing is turning the idle adjustment screw has
absolutely NO effect on reducing the 2500 RPM idle.

Time to test the usual suspects one by one.

Todd
'88 Westy

Mark G wrote:

>Just got my '87 Westy back from the shop today. I wanted them to install new ground cables and clean all the grounds. I also wanted them to check a surging problem, and a cold idle problem which (of course,) mysteriously vanished on the drive over to them.
>
>They suggested I install a new idle stabilization valve and a new idle stabilzation control unit. (Both very expensive) Anyway, upon arriving at my driveway and putting the van into park, the idle shot up to about 2500 RPM and stayed there, even after I kicked the throttle a bit.
>
>FWIW. The ISV is definitely buzzing, and I cleaned all the contacts on the control unit a couple of months ago. Any ideas?  This needs to be sorted out soon, as this van may be a daily driver come March.  TIA.
>
>Mark Garcia
>Alhambra, CA
>1987 Vanagon Westfalia (for going slow)
>2000 Passat 1.8T 5SPD(for going fast)
>1981 Vespa P200E (for just going!)
>
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