I'm hoping some of you Chrysler guys out there can help me. On a Chrysler a/f sensor what is the voltage sent to the sensor from the PCM. how exactly does this work? Does the PCM send 5v and 2.5v to the sensor and monitor the feed back on the 2.5v signal. And any ideas on how we could modify the signal.

 

whats an AF sensor? what are u tying to do any way?

 

You titled your question "o2 sensor help" and then asked about the AF sensor. Are you asking about the MAF (mass air flow) sensor? This is not the oxygen (O2) sensor. Oxygen sensors measure oxygen in the exhaust gas before and after the catalytic converters to monitor how well they are working.
TheMAF sensor operates in the intake air to measure the amount of air flowing into the engine. They work by keeping a constant temperature in a heated wire. As the air flow varies, a different voltage is required to vary the current to keep the wire at the constant temperature. The engine computer monitors the voltage and thus has a measure of the air flow. Asthe air flow varies, the computer will vary the pulse width of the fuel injectors.
If you are trying to get better power or economy out of the engine, maybe you could add or subtract some resistance to the circuit and thus fool the computer, but unless you know what you are doing and have a dynamometer handy to calibrate your work, you are much better off to not fool around with the engine calibration.