>From: Jim Piper

I'm sorry. I forgot to post my e-mail address. Dumb mistake. I'll repost the
message, then add the address. Sorry for the double posting.

Hi. I have an 86 Vanagon with roughly 74,000 miles on it. Over the weekend, it
developed a new problem that I am having problems tracking down. While warming
up the car on morning, the engine reved from its usual 1,000 rpm to
aproximately 4,500 rpm and stayed there until I shut it down. Since then, it
has happened numerous times, including while driving. It does not seem to be
pulling full power when it does (it will only pull the car at 50 mph or so)
and I can go faster by pressing on the gas pedal. Engine temperature seems to
have nothing to do with it.Oh, it is the manual transmission.

Looking through the Bently manual, it seemed to suggest that the idel
stabilizer could be allowing air to bypass the throttle valve, so I tested it.
At times when the engine was running properly, the idle bypass valve was
humming and vibrating as the manual said it should. When the engine went to
high rpm, I shut it off and turned the key back on and the valve was not
vibrating. There was 12 v at the valve connections. Turning the engine back on
right away again produced the high rpm. After several minutes with the engine
off, I checked it again and the bypass alve would vibrate. Starting the engine
at this point produced a normal 1,000 rpm.

 A member of this newsgroup had the good suggestion to try tapping the valve
body with a hammer while it was misbehaving (wish I could do that to some of
the people I work with), so I will try that tonight.

 My questions are first, has anyone experienced something similar, and if so
did replacing the idle stabilizer valve fix the problem? Second, does it sound
like the idle stebelizer valve could produce this problem? Bently is not too
much help (at least in this case) as it doesn't get down to basics and tell
you how the system works or how to trace down problems.

 I would greatly appreciate any help/suggestions that could be offered.

My e-mail address is JPIPER@UMDACC.UMD.EDU