There are many sensors and wiring connections in the Fuel Injection
system and it wiring harness that can cause an intermittent operation
problem.

Many times on the list people post after their mechanic has charged them
for lots of time and parts and yet not cured one of these problems (or
other operational problems).  And a reasonable percentage of the time
the cure is one related to bad grounds or bad wiring.  In other words
nothing had been accomplished by the previous work and parts.

Grounds far from the problem area, such as the one on the transaxle
nose, can create the problem.  It is not just loose grounds, but ones
with corroded connections.

One of these problems is the original "Vanagon Syndrome" which is caused
by a worn track in the AFM.   When the tip of the sensor arm in there
sits over that spot for some length of time during highway driving, it
sends intermittent signals to the ECU leading it to temporarily cut out.
  There are three fixes.  First, there is the expensive harness built by
VW which plugs in between the usual connection from the harness to the
AFM and AFM itself.  Second, there is the Capacitor fix.  A capacitor is
soldered across two of the 4 wires in the connection of the AFM and
stabilizes the output signal, preventing the drop offs from the worn
spot.  The ECU doesn't get erratic signals and the van runs smoothly.
This replicates part of what the harness addition from VW does.  Doing
both 1 and 2 would be redundant.  The third fix actually attempts to
remove the worn spot from the operation of the AFM.  The AFM top is
removed to reveal the internal electronics.  There is a small circuit
board with an arc on it inside.  The board is loosened and moved a small
distance so that the arm doesn't travel over quite the same arc and
misses the worn spot.  This supplements 1 and 2, or maybe, if tried
first, obviates the need for either one of them.  Many have done this
successfully.  I tried this on one spare AFM box and could never get the
board loose.

There are literally mountains of information about this in the
vanagon.com archives, and on individual websites.  I have a pile of
information about it stored on my hard drive, some of which is quite old
since I downloaded it when I first joined Vanagon.com and had an
intermittent bucking problem in my 84.  This turned out to be cause by
another part which was far cheaper than the AFM and took 5 minutes to
install.  I too had given at least $1000 to mechanics over a 2 year
period trying to solve the problem.  It would have been far more, but
nice guy gave me back my money when he install a new ECU and the car
quit on me the next morning leaving me stranded on the other side of
Baltimore.

I will send out a group of files to anyone who asks me by tomorrow
(Wednesday morning).  Included will be more than info about the AFM
related Vanagon Syndrome, as there are other gremlins that can attack
the FI system and cause similar problems.  These are the same files I
have sent out before.

--
Sam Walters
Baltimore, MD

89 Syncro GL, Zetec Inside
85 Westy Weekender
85 Mercedes Benz 300D Turbodiesel - to become veggie oil powered

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