OK
New o2 sensor installed and it doing exactly the same as before.
With engine warm and running and o2 sensor connected, Ive got 0.92 v  sensor to ground. Does not come down and engine stumbling on throttle open.
Disconnected sensor heater and sensor voltage slowly come down to 0.45v and stumbling goes away.
Engine off,  Green sensor wire disconected. It looks good and has no continuity to ground or shield. It has continuity to pin 2 ecu.
Shield is grounded to distributor ground.

While running I plugged the heater back in and the sensor voltage started to climb slowly to 0.92 v

Ive refreshed the grounds on firewall and side recently but am going through them again.

Dennis 
If testing with a dry cell battery how do i tell its going lean or rich?   Engine running? Check voltage sensor to ground?

Thanks 
 Bob
 
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> On 23, Mar2020, at 4:26 AM, David Beierl <dbeierl@GMAIL.COM> wrote:
> 
> ---------- Forwarded message ---------
> From: David Beierl <dbeierl@attglobal.net>
> Date: Mon, Mar 23, 2020 at 5:26 AM
> Subject: Re: O2 Sensor problem
> To: Dennis Haynes <d23haynes57@hotmail.com>
> Cc: vanagonlist a <vanagon@gerry.vanagon.com>
> 
> 
> Rarely will an O2 sensor go over 1 volt so what happens is that even after
>> the O2 sensor is saturated and reaches its limit the ecu is still trying to
>> go rich until it sees something.
>> 
> 
> High voltage signals rich and should drive the ECU lean.  However I think
> the programmers must have anticipated the possibility of heater element
> leaking to the sensor, because this condition in fact drives the ECU rich
> just as does a sensor line shorted to ground does.
> 
> Yrs,
> d