Date:         Thu, 11 Jul 1996 09:44:52 PDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Shawn Wright" <SW@smus.bc.ca>
Subject:      Re: '87 Synro jerky running on highway

On 11 Jul 96 at 9:55, RobHalliga@aol.com wrote:

> Could anyone help me diagnose this problem with my '87 syncro? When I've been
> on
> the highway for more than an hour the van will start jerking like its starved
> for fuel. When 
> I pull over while its happening, it stalls. It never stalls otherwise. Then
> it starts right up and runs fine for another hour. This would be very hard to
> reproduce for a mechanic.
> I've owned the van for 2 months and 5000 miles. It only has 56000 on it.The
> problem just started on my last of many 200 to 300 mile trips by highway. The
> tach doesn't move during the incidences and the prob seems to be speed
> sensitive--60 to 70
> on level road. The jerks got larger with each hourly episode. Is it the fuel
> filter, fuel pump, something with the limited slip or what? One  factor could
> be that, I just disconnected the seat belt warning buzzer before the trip.
> Perhaps that effected the fuel pump? Although the wiring diagram seems to
> contra-indicate any connection.  I'm afraid to leave on a planned  trip cross
> country with my van running like this. Thanks for any advice.
> 
Sounds like the common airflow sensor resonance problem - my '88 had 
it also, but at low speeds, like when crawling in traffic. Yours may 
be solved by the resistor harness - I haven't tried that yet. Others 
on the list can tell you about this fix.

What I did to fix mine (which *may* apply to yours also):

Find the airflow sensor - it is contained under the 3x4" black
plastic cover to the left of the airfilter housing. Carefully pry
this cover off (it is glued on), then have a look at the trace of
the wiper arms across the circuit board material. Mine had worn
through the surface in a few places. By *carefully* bending the
wiper arm so it traces along a different path, the problem went
away. I resealed the cover with silicone & have driven 6000km since
with no problems. 

The micro switch under the throttle body can also give problems, but 
usually at idle or full throttle when the switch is supposed to 
open/close. Might be worth checking this also - mine was stuck at the 
idle position.





Shawn
'88 Westy 332k (Kyra)
'85 Jetta TD 350k (Jenni)