It sounds like it is the temp II sensor.  Check the plug on that and the
wires...Mine are all brittle and the plug sucks.  If you unplug the Temp II
and the running behavior doesn't change...that is probably it..some kinda
connection issue...since you say you know the sensor is good again.  Those
things (the sensors themselves) are sometimes no good even when new..Bosh..
  Don Hanson

On Tue, May 26, 2009 at 8:04 AM, David Clarkson <Dvdclarksn@aol.com> wrote:

> Just a follow up to the previous post. The oxygen sensor voltage seems to
> be swinging between .1-.7 volts with the engine warmed up. Thanks for any
> help  that you can offer fellow vanagonauts.
>
> David
>
>
> In a message dated 5/26/2009 10:34:31 A.M. Eastern Daylight Time,
>  Dvdclarksn@AOL.COM writes:
>
> I'm  having an intermittent rich running problem with my 90 2.1 liter
> Westy.
> This was the same symptom that I had that was fixed 13 mos. ago with  a new
> temp  II sensor. This has been replaced with no effect. One  other
> interesting thing  that I noticed when attempting to install a  wire to
> feed an oxygen
> sensor  monitor was that just connecting an  additional wire to the sensor
> causes an  immediate rich running  condition. I had a problem this morning
> when the engine  was started  cold with running rich also. Am I looking at
> a
> problem involving   cleaning up some grounds again. I'm thinking that I may
> also
> need to test  the  voltage coming from the sensor and also at the ECU. Any
> ideas  towards diagnosing  this problem would be greatly  appreciated.
>
>
> David  Clarkson
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