Date:         Fri, 14 Nov 2008 18:17:00 -0800
Reply-To:     Don Hanson <dhanson@GORGE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Don Hanson <dhanson@GORGE.NET>
Subject:      strange idling behavior ? (long post with plenty of diagnostic
              hints)
Content-Type: text/plain; charset="Windows-1252"

84 vanagon with an inline VW 1.8 motor.

  Not really a vanagon question, I guess but many on the list seem pretty
familiar with the little inline 4 VW motors.  They also have the same or
similar fuel injection to vanagons, so Helpful hints would certainly be
appreciated as to where I might look.

This little 1.8liter, 8-valve, from a '92 rabbit cabriolet (Digifant II
injection) , has always behaved perfectly until just this morning.  Upon
start up..not super cold or anything, the idle didn't drop like it always
has after the motor warmed up.  It usually runs at like 1200rpm for a few
minutes, then drops down to a normal idle..This morning it seemed to be
idling a little higher than normal, and it didn't fire up and settle right
into it's pace, but kinda stumbled around a bit, then settled in at it's
warm up RPM.  (no throttle from the gas pedal, ever)

 No dash warning lights, no abnormal driving preceded the onset of the
problem, all the gauges read the same as always.  I did run the tank dry a
few weeks ago and I have noticed my fuel pump is slightly more audible than
before, but I've had no indications that the fuel pump is having
problems...yet.  And it does run fine down the road..

  I headed out, with the high idle,  and at my first normal stop sign, the
idle was still up at around 12-1500rpms.  It normally would have gone to
it's regular idle (about 7-800rpms, I guess)  mode by that point, but not
today.  Then, as I came into the next stop-after about 20 miles of highway
speeds,( totally normal behavior, other than the high idle between shifts)-
the idle was "hunting"...it was doing about 3-second cycles...Up to
1500......down to normal....up......down... up..I blipped the gas pedal
without any effect to the hunting...It did that for my cross town trip of
about 3 miles and a couple of stop signs, then I shut it off and went bike
riding...It cooled down for about 2 hours then.
  Under throttle, when driving, everything seems to be running properly.  No
smoke, no missing, no detectable loss of performance.  Weird... I drove
around town and put about 45 miles on today with no problems other than the
high/and or/hunting idle..
  Just now, coming home, the 'hunting' has stopped again, but the idle
remains much too high...1500+ rpms (guess-ti-mate)  I left the van running
and went round to check the exhaust...smells normal..not super-rich or in
any way stinky.

  So, any guesses or suggestions?  First thing I'll be looking at will be
the Temp II sensor, my guess.  That seems to cause all kinds of weirdness in
the Digifant II system and other VW injected vehicles.  I have never been
able to find a 'throttle position switch' on this vehicle...but then the
Bentley I have (for the Cabriolet motor) is not worth squat on that
particular point..I may not have one, who knows..I wouldn't think that would
cause the "hunting"...Hope it isn't the EMS Brain...

  Thanks in advance...Hey, it's even Friday so if this isn't list
appropriate..it's at least posted properly..

  Don Hanson

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