Date: Thu, 6 Aug 2009 22:26:17 -0500
Reply-To: joel walker <uncajoel@BELLSOUTH.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: joel walker <uncajoel@BELLSOUTH.NET>
Subject: Re: 1.9 automatic vanagon syndrome ??
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> Definitely not Vanagon syndrome -- that only effects 2.1 L engines
the first tech bulletin that came out WAS for only the 2.1 1986-1991
engines.
but ...
vw re-issued it a bit later for ALL water-cooled vanagons ...
=======================================================================
from Service Bulletins, Model Year 1992
......................................................................
Technical Bulletin
Group: 24
Number: 92-02
Date: April 30, 1992
Subject: Vanagon Driveability Complaints
Model(s): All Water Cooled Engine Vanagons
SUPERCEDES TECHNICAL BULLETIN 24-92-01 (February 29, 1992)
CONDITION
After driving for an extended period of time at a constant speed, the
vehicle may, on occasion, experience a deterioration of performance
which may be accompanied by a hestiation or surging.
In many cases, after turning off the engine and subsequent re-start or
without having taken any action, the symptoms disappear. These
symptoms
may not recur for several weeks or months.
SERVICE
To resolve this condition, wire harness Part No. 025 906 302A, should
be
installed. This harness provides improved signal voltage
stablization.
* remove electrical connector from air flow sensor
* install wire harness, Part No. 025 906 302A, between main harness
connetion and air flow sensor connection.
*****************************************************************
* CAUTION *
* Part numbers are for reference only. Always check with your *
* Parts Department for latest information. *
****************************************************************
NOTE
When troubleshooting this system and performing continuity checks, the
following should be noted. Due to active components in the wire
harness, Part No. 025 906 302A, there is not continuity between pin
two
of the connectors. The following chart on page 2 lists the resistence
of each circuit.
---------------------------------------------
Terminal Approximate
Number Resistance
---------------------------------------------
1 Zero Ohms
2 Greater than 1 Meg. Ohms
3 Zero Ohms
4 Zero Ohms
5 Zero Ohms
NOTE
If customer complaints persist after performing the above repair,
contact your Zone Product Support Specialist for assistance.
........................... end ......................................
harness costs about $100! very simple to install. takes about three
minutes maximum. the new harness fits between the old harness and the
silver air-flow meter box attached to the air cleaner box. remove the
silver clip, wiggle out the big wiring connector (from the side of the
air-flow meter), connect the proper end of the new harness to the big
big wiring connector you just wiggled out, put the new clip into the
new connection; then take the other end of the new harness and plug it
into the air-flow meter connection. put the silver clip back. and you
are done.
=======================================================================
and some other comments on the problem ...
IMPORT SERVICE MAGAZINE
July '93 Vol. 6 No. 8
Subject: more 'Ghost harness' info
After driving for an extended period of time at a constant speed, some
water cooled Vanagon engines may loose performance or hesitate and
surge.
In many cases, the symptoms will disappear after turning off the
engine
and restarting. After that, the symptoms may not reoccur for several
weeks or months.
A new wiring harness (P/N 025 906 302A) is available to correct this
problem. The new harness provides better signal voltage stabilization
than the old harness it is designed to replace.
To install the new harness, remove the air flow sensor harness
connector. Install the new harness between the main harness
connector and the air flow sensor connector.
There are active components in the new wiring harness. For this
reason, there is no continuity between terminal number 2 at one
of the harness connectors and terminal 2 in the harness connector at
the other end of the new harness. This is normal and should not be
considered a fault.
All other connector terminals should have 0 ohms resistance from one
harness connector to its mate in the connector at the other end of
the harness. Keep this in mind when troubleshooting this system and
performing continuity checks.
From: "Dan Houg" <HOUGD@mdh-bemidji.health.state.mn.us>
========================================================================
My first experience related to the problem was when I drove on the
highway on
a constant speed and after an hour or so my engine just suddenly lose
all
power, and after I stop and start again it work fine , the same
problem that
Derek has told about in the Technical bulletin TB#12 and TB#13 he has
put
togeteher from VW information he has. I phone some friends in Sweden
and
quite soon I understod that the problem was known as well as very
special.
This was back in 93.
It seems like that the fault first was found in Sweden but when
reported first
didn't the german compane Boch belive that it was a problem with the
air flow
meter but a local VW service person use a oscilloscope to monitor the
output
voltage from the resistor wiper that measure the air flow value during
a long
measuring time. And his work pays off; He found out that if the engine
runs
for a long time very constant and specially also when the weather type
is
little frosty then the wiper could start to lose the electrical
contact on the
resistor trace (It is not to easy to find the word in english, but I
think you
understand what I mean) and the voltage starts to oscillate instead
of have
a relative stable value.
The DIGIJET (and probely DIGIFANT) electronically box accumulate this
oscillator voltage value , but after a while it thinks it is a
malfunction and
shut of the electronic pulses to that control the gasoline flow to the
engine:
the engine suddenly lose all power !!. When the engine is restarted
all memory
in the control box is reseted and the engine runs fine until the same
situation happens again , that can take days, weeks or may not happen
again
The solution ( (if the gurantee is passed and you don't want to try
the $100
version first )at least for a while ( if the air flow wiper resistance
trace
is totally unconducting(worn out) then the whole air flow meter has to
be
exchanged)) is to stabilize the output voltage round its oscillating
average
value., The air flow box connector has four pins. Between pin 1 and 4
is the
NTC-1 resistor that measures the temperature inside the air flow
meter.
Between pin 4 and 3 is the Potentiometer endpoints and pin 2 is the
wiper of
the potentiometer that moves by the air flow and also is the output
voltage
signal that must not oscillate. The easiest way is to add a $0.5 25 V
10 uF
tantal capacitor with its +side connected to pin 4 and its common to
pin 2
(who is the air flow voltage output) to stabilise the voltage. Later
Boch
came out with the $100 box that I think more or less make the same
thing.
Practically I mount the capasitor on a two wire 15 cm cable that I
solder on
the pin 4 and 2 (note the polarity) in the connector that mounts on
the air
flow meter box on the top. and then taped so it was completely water
resistant
and dust resistant.
I can only say that I have not have the problem ever since. but You
never know
if this fix was the whole solution for the engine power lose. God
Luck!! If
it not works , don't blame me, if it works use your other $ 99 to
something
more fun!
Lars Herrnsdorf
Gottenborg Sweden
========================================================================
From: smitht@jupiter.sun.csd.unb.ca (Tim Smith)
Unsolicited endorsement, from a sample size of one vanagon: This does
work,
cleared my probs immediately, so far for 14months now. My only rec. is
that
when installing simply pull back the rubber boot exposing the 4 wires
that
go to the connector. Find #s 2 and 4 and simply nick them for a 1/2"
or so
to expose the bare copper. Pry the wire out of the insulation by
pushing a
nail/knife under. Then solder the capacitor right across the bared
loops of
copper. No 15cm leads, no fighting with connector lugs etc. Use some
electrical tape over the solder sites then tuck, everything neatly
back
inside the rubber boot. The capacitor I used was a 25Volt
22microfarad
tantalum type. I read of mention of the stuttering problems not being
completely solved with 10ufd size, quoted from a LIMBO article (via
email)
maybe?
NOTE: it says to use #2 as positive, #4 as negative !!! I used it
this way.
Any electrical geeks wanna tell if it makes a diff in this
application? Prolly.
Tim Smith
'87 non-stuttering Syncro
