it goes to the evap control device.....a vacuum operated valve.
which is hidden on the forward side of the firewall on a 2.1 wbxr vanagon.

you will find it in the 'fuel supply' section of Bentley I believe.

the valve allows gasoline fumes to be absorbed by the charcoal canister when
the engine is off.
when you start the engine ..vacuum from the throttle body opens the valve ..
so the stored gas fumes are sucked into the engine and burned.

it's just vacuum hose available at any FLAPS.
The system has very little affect on engine operation.
it's a smog device..
a very good rather passive device.  No electrics involved, usually works
'forever'  ( though I have seen a charcoal canister where the charcoal is
falling out of the bottom. You can see it in your right rear fender well
area.  a tall black plastic can ) Just connect it with good new hose.

Scott
www.turbovans.com

----- Original Message -----
From: "John Rodgers" <inua@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, June 18, 2011 1:57 PM
Subject: Throttle Body Question

>  I have an '88GL, 2.1L WBX, manual tranny. The fuel system is Digifant.
>
> The throttle body lays transverse over the engine. From the Right hand
> side of the firewall, through a hole, there is a plastic tube that comes
> across and attaches by a little rubber hose to a nipple on the forward
> (firewall) side of the throttle body. The hose is rotted through and
> needs replacing.
>
> I cannot find a picture with that nipple showing, nor that plastic tube.
> May have just missed it in Bentley, but what is the purpose of that tube
> to the throttle body, and where does it go/come from through the
> firewall? How does it affect engine operation?
>
> Thanks,
>
> John
>
> --
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com