as another poster mentioned.........check idle switch contact at idle, and
how close to 'zero throttle' the contact point is.
...especially if it's at light throttle, and very small throttle openings,
as might occur going around a city turn .

I had this in my 2.1 engined 85 Adventurewagon ( FS btw ) . It even has a
shiny new throttle body and new switch on it ...and at very light throttle,
it would do just that, buck.  Accelerate a little.......and it was fine. Try
to drive steady at low throttle.......can't do it, too much bucking.

I checked 'when' the throttle switch was making and breaking contact.
( it's in the Bentley .....the precise german way to adjust it ) .
I found perhaps a quarter inch of throttle cable travel ( checking it by
hand at the engine ) before the idle contact switched off.
So that means I could be at say ..........some throttle angle above idle ,
like up to 10 % opening ......yet the switch would still be closed, telling
the ECU it's still at idle .
  I adjusted that so quite slight movement of the throttle will result in
the switch clicking open, and each time I release it back to idle .....the
switch closes for sure.
I find that it tends to not return to full, full zero .........so you have
to check that it also makes contact, and clicks, each time you release the
throttle.......even from only slightly open, and gently released.
Doing that ...........only moved it into the shop since that adjustment, but
I bet it's fixed for the bucking I was getting at light throttle.
I've seen some worn enough .........I think, anyway........that were too
worn to reach proper adjustment.
I have one 2.1 throttle body that's just generally funky and worn .....and
it doesn't seem to want to return cleaning to idle position quite.  Point
is, the throttle body and/or switch can be too worn to work really
correctly.

Be nice if it was just that simple adjustment for you !
I find them adjusted incorrectly quite regularly on vanagons.
Scott
www.turbovans.com
----- Original Message -----
From: "Joel Cort" <joel_cort@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, July 06, 2009 3:27 AM
Subject: Help with van bucking and spitting

Hey gang,

I'm trying to help out a buddy with a 86 2.1Ltr. Westy.

The van idles great hot or cold and starts right up.

While driving along all the sudden it will hicup and miss loosing all RPM
under load. And pick right back up.
When slowing down to take a turn and picking up speed it will buck and miss
with some backfiring.

I have checked the wiring and it all looks good. I have also checked and
replaced the easy things like:
New TempII sender and
I swapped a good AFN (out of my van) AFM
A good Idle Stabiliser relay

but the symptons are still there.

Any hints where and how to track this gremlin down? I will swap the brain
next and the O2 is new.

Thanks,
Joel Cort
Rochester NY.

89 Syncro Westy (CinnabarVan)
87 Syncro Transporter (Stella)
73 Westy Campmobile (agent orange)

Founding Member of the Empire VW Camping Club
&
Westies at Watkins - www.westies-at-watkins.org