If less than $200, not very accurate. Google a bit on narrow-band vs. wide-band 02 sensors to see why. In a nutshell, the cheaper narrow-band sensors test for a given state -- and the results indicate whether the gas mix is in that state (the narrow band), above it, or below it. Thus, all you can really strive for is a fast cycle alternating up and down. Wide-band 02 sensors actually provide useful numbers across a calibrated range... but I haven't seen one for under $400.


No, for a narrow-band o2 sensor. Yes, for a wide-band o2 sensor.


That's easy -- the ratio is the same for all gas motors. You're shooting for stoich, at 14.7 or so.

Here's a tool I'd love to have: http://www.widebandcommander.com/

..and here's a relevant FAQ which should get you started:
http://www.widebandcommander.com/faq.htm#1

Randii