Hi Rich,
     For proper o2 readings under most circumstances it is adaquate  to have
the exhaust system in proper condition.  Then clean the grounds on the
transaxle nose, both ends of the strap from the left head to the vans body
near the coil, and all the other brown wires on the left head and  near the
coil.  Clean / polish the connections so they will make good contact.
     A better solution may be to install a 4 wire o2 sensor. Wire up the
white and black wires  as normal then  take another wire from the gray o2
wire and connect it to the  ecu pin 19 ground.  I have never tested a 4 wire
o2 sensor on a van but it should provide the ecu with a very precise
exacting mixture reading from the o2 sensor.  Many cars after about 90
models use the 4 wire sensors.
    It would be difficult to attach a seperate ground wire to a 3 wire
sensor that would keep a good conections after all the heat /  cold cycles
the o2 sensor is subjected to.
Darrell

----- Original Message -----
From: "Rico Sapolich" <JKrevnov@AOL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, November 01, 2000 8:50 AM
Subject: Re: WRONG INFO - O2 Sensor, Bucking, etc.

> In a message dated 11/1/00 8:56:51 AM, midwesty@midwest.net writes:
>
> << The minus signal must travel from the sensor
>
> device assembly,  to the o2 case,  to the exhaust system,  to the engine,
>
> and then to pin 19 of the ecu wiring harness.   This is why the grounds
are
>
> so critical on our vans. >>
>
> Darrell,
>
> So, it would be beneficial to clamp a terminal on the body of the OXS and
> bond it to the reference ground.
>
> Rich
>