> My '85 is running better with the O2 sensor disconnected. I have a problem
> at idle and when accelerating from a stop when the engine is cold with the
> O2 sensor connected. I have tried a generic no name from Napa and then
> went to the generic Bosch with wire from an old one. Neither made any
> difference.
>
> Any ideas?

Unless I am greatly mistaken, the ECU has a "factory default" mode that it
will revert to if it cannot get a recognizeable reading from one of the
sensors that it relies on.  In its default mode, it will ignore the readings
from several of the F.I. sensors and use its own factory preset.  Therefore,
disconnecting one sensor (such as the 02 sensor) essentially removes several
from the circuit, any of which could be the faulty one which is causing the
van to run improperly.

Another possibiliy (although less likely given your symptoms) is that in the
past someone has adjusted the fuel mixture based on the existence of an 02
sensor that was giving incorrect readings.  Now that you have installed one
that does work properly, this "compensating" fuel adjustment is causing the
mixture to be way off.  You may want to have a shop with emissions testing
equipment look at your emissions levels.

- Ron Salmon
 The Bus Depot
 http://www.busdepot.com
 (215) 234-VWVW