An oxygen sensor generates its own voltage, supposedly from 0-1 volt and it changes very rapidly. A "perfect" 14.7:1 air/fuel ratio which produces exhaust emissions of nothing but CO2 and water vapor is 0.5 volts. The term for that condition is "stoichiometric". You'll need some sort of stand-alone computer that is capable of sampling the O2 sensor output several times a second. The older GM computers had a clock circuit that worked at 10 Hertz (cycles per second) but I believe most of the newer systems have a much higher sample rate. At one time MOPAR was using a 90 hertz clock circuit. I believe there are some aftermarket kits that include a dash gauge with a digital O2 readout.
Jerry

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