Date:         Wed, 21 May 1997 22:41:22 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         mholser@Adobe.COM (Malcolm Holser)
Subject:      RE: unplug '86 idle stabilizer?

> I have had my idle stabilizer, 1987 2.1l, unplugged for about 4 months.  =
> My VW dealer actually disconnected it, I have since added a switch to =
> turn it on for cold starts.  The idle was at 2000 before it was =
> disconnected, it ran at about 1000 for a while, now it's back up to =
> 2000.  When the idle stabilizer is connected it idles between 3000 and =
> 3500.  To get the RPM's down I now turn on the A/C.  I believe my =
> problem might be related to the hole in my exhaust that I haven't fixed =
> yet, I have the pipe, just not the bolts yet.  I hope the idle goes down =
> when I fix the exhaust, do you think the exhaust is the problem?

Definately fix your exhaust.  While most people seem to not realize it, a
sealed exhuast upstream from the O2 sensor is critical for proper operation
of the system.  While it would appear that exhaust would only come OUT of 
a hole, this is not the case.  The exhaust is pulsed with the firing of
the cylinders, and it will suck in air on alternate cycles.  This air will
make the O2 sensor think the mixture is too lean, and the computer will 
send in more fuel to "correct".  This wastes gas, and the car runs (and of
course sounds) like crap.

All that said, I think it would not be affected by unplugging the idle
stabilizer.  If the hole in the exhaust is screwing up the FI, the test
is to unplug the O2 sensor.  If things run better, then your exhaust is
the culprit.  With the O2 sensor unplugged your system will run in "open
loop" mode, and any holes in the exhaust will not have much of any effect.

If your idle is affected by unplugging the idle stabilizer control unit, 
then you *might* have a bad unit, or a bad temperature sensor, or a leaking
cold-start injector, or any of a myriad of troubles.  Basically, you should
go through the FI system step by step as in the manual.  There are way too
many factors to do anything else and hope for reliable results.

malcolm