John,
  If you have access to an ECU to swap in, it might be worth a try.  I was
struggling with a '91 about a year ago.  It had various running/idling
problems that I gradually solved; during which I put in an ECU that I had
once tested and found to be OK.  Suddenly the van refused to idle down
properly and nothing I did could fix it until I put the original ECU back
in.  The idle was not 3K, more like 2300, but way too high.  I repeated the
swap to be sure and retired that ECU.  I looked at the circuit board, but
could not see anything suspicious.

Larry A.

On Thu, Oct 10, 2013 at 4:54 PM, John Meeks <vanagon@gmail.com> wrote:

> Thanks Scott -
>
> I'll try unplugging the ISV next time it does this. I think that's a good
> troubleshooting first step. Not sure yet what it will tell me. I think that
> valve just add more more less air to the mix. You can hear the little motor
> running in there with the key on.
>
> It's probably worth inspecting the ECU solder joints with a strong
> magnifying glass too. I'll be able to do that this weekend.
>
> John
>
>
>
> On Thu, Oct 10, 2013 at 3:28 PM, Scott Daniel <scottdaniel@turbovans.com
> >wrote:
>
> >  I sure wouldn't call 3K rpm 'runnaway' ..though it does sound really
> > dramtic to discribe it that way.
> > if it was really runnaway ..
> > it would be screaming at 6,000 rpm or so.
> >
> > I wouldn't think that the TPS telling the ecu that your at full throttle
> > would do this.
> > I believe all that does is bypass 02 input at WOT.
> >
> > And ..I have seen the electronic control unit and/or idle air valve cause
> > this.
> > I've had a vanagon sitting in a bay of my shop idling ..
> > suddenly jump to very high rpm all by itself.
> >
> > Unplug the Idle Air Valve right there on top of the engine.
> > ISV valve sometimes called too.  Idle Stabilizer Valve.
> >
> > Scott
> >
> >
> >
> >  On 10/10/2013 9:44 AM, John Meeks wrote:
> >
> > Yesterday I was in a 2 mile stop and go traffic jam. About 3/4 of the way
> > the low speed fan came on as expected. A minute later the engine revved
> up
> > tp 3K rpm and stayed there. The gas pedal was all the way up. Couldn't
> get
> > off the road so I turned off the engine when there was a stop situation.
> > Turning it back on the engine revved right up to 3K again.
> >
> > Finally pulled into a parking lot and waited about 15 minutes. Started
> > normally with no recurrence the rest of the way home.
> >
> > I had this same problem about a year ago (intermittant) and 'fixed' it
> with
> > a new throttle cable and cleaning out the rust and dirt from the pedal to
> > cable housing. Now it's back!
> >
> > Side note  just put the engine in after head gaskets and ring replacment
> > and It was running great for the past week.
> >
> > Could the TPS be the culprit if it made the ECU see full throttle and ECU
> > then enriched the mixture?
> >
> > Any ideas are welcome.
> >
> > John Meeks
> > '91 Vanagon MV Phoenix
> > Stock 2.1 250K miles
> > Northern Michigan
> >
> > Vanagon Rescue Squad <
> http://www.vanagonauts.com/Vanagon-Rescue-Squad74.htm> <
> http://www.vanagonauts.com/Vanagon-Rescue-Squad74.htm>
> >
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> > www.vanagonauts.com
> >
> >
> >
>