At 04:52 PM 6/24/2015, Tyler Hardison wrote:

>My '85 Weekender is doing the same thing. I was going to pull the throttle
>body and give it a good cleaning and adjustment this weekend. I suspect
>that the throttle never fully closes but the burp snaps it back into place.
>
>--t

Many/most of these old throttle bodies are worn out.  VW took the
approach that the throttle plate would be the thrust bearing that
holds the shaft in position vertically, so both plate and bore wear;
combined with wear in the bushings you end up with a butterfly
assembly that moves both horizontally and vertically, and has a
different rest position when air is flowing through it.  So if you
can't afford to fix it properly you have to set the idle switch with
the engine running, and you may have to add material to the end of
the idle asjust screw to get the basic idle down to spec.

That said, on a 1.9l (Digijet system) the idle switch plays no role
in setting rpm, it's a logic input to determine whether the ECU
should go into deceleration (fuel shutoff mode.  Failing to open will
give you serious heartburn that cannot be ignored, but failing to
close will only affect your wallet.

Yrs,
d