Geza,

It sounds like your electronics (and your electronic troubleshooting
skills) are in good order, new O2 sensor, sure and solid grounding., new
TempII sensor... I'm beginning to suspect that your engine *really is*
running lean when you see that low O2 signal.

Have you looked into fuel supply issues? I've seen lots of posts on the
lists about clogged filters, floating rust flakes clogging the pickup in
the tank, and bad fuel pump. I would expect that any interruption in fuel
flow *should* cause the engine to run lean, and the O2 sensor signal should
reflect the lean condition.

About the only electronic thing left would be some intermittent problem in
your harness or ECU pulling the signal down. Unlikely, but anything is
possible.

Tim

At 12:16 PM 2/16/2006 -0500, Geza Polony wrote:
>My interpretation of the whole thing (I'm dealing with similar issues) is
>that the O2 sensor works, no matter what temperature it's at, but the ECU is
>programmed not to pay any attention to the voltage it produces until the
>Temp II sensor says the engine is warm enough. Before that time, the O2
>sensor produces voltage, but it's erratic.
>
>I installed one of Ken Lewis' O2 sensor volt meters on my instrument panel
>to have a constant monitor, and it's truly eye-opening to see what's going
>on. When the engine's running rough and has no power, sure enough, the
>oxysensor is putting out low voltage, indicating a lean condition.
>
>If I were to replace the one-wire oxysensor system, it would be with a
>four-wire, not three, because I think the ground needs to be absolutely
>certain for these to work, and the old tailpipe structure seems a poor
>ground at best. I grounded my O2 sensor with a wire and a radiator hose clamp.
>
>The engine will run ok without the O2 sensor, but you'll spend a lot on gas...