On Mon, 31 Mar 1997, Cory Zumbrennen wrote:

> Since returning from Baja my Vanagon, an '86 Westfalia, will not
> run with the O2 sensor connected. [snip]
> When I
> disconnect the O2 sensor the van runs great...better than it used to run 
> when the sensor was working.  However my gas mileage goes to crap, and it 
> wasn't that good to begin with. 

This sure sounds like a bad sensor/sensor connection situation.  You can
give this a test by getting the engine good and hot.  Disconnect the O2
sensor and start up the engine again.  Put an appropriate wrench in the
idle air mixture adjusting screw and an volt meter on the disconnected
O2 sensor.  Screw the wrench all the way in (count your turns so you can
get it back to its original setting) and the volts coming off the O2 sensor
should jump up to the .9 to 1.1 volts range.  Screw it all the way out and
the volts should drop to around .3 volts.  If you get these kinds of fluc-
tuations, then the O2 sensor is OK, and you probably have a wiring problem.

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Tom Young               young@sherlock.SIMS.Berkeley.EDU
Lafayette, CA  94549    '81 Vanagon
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