One thing that is missing from this thread is a separation between NARROW band and WIDE band O2 sensors.
Deves first comments seemed to describe a NARROW band sensor. If that is correct I would have to agree with HotRod Lincoln. The narrow band sensor is designed to flip up and down around the stoic point of 14.7:1 air/fuel ratio. This flipping is nearly impossible to work with unless you have a computer as HotRod describes. Narrow band is '70s technology.
WIDE Band is a completely different animal and gives a nearly linear output curve over the whole range of air/fuel ratios 5.0-20.0. It will teach you a lot about what is "actually" happening in your engine.
I always recommend welding in an O2 bung on ANY engine so you'll have it if you want to test and tune. Wide band sensors and systems are relatively cheap these days at about $200.
Paul
