o2 sensors, help on sensors Options

[Ericsofrosty]

So I have an important question, if i'm correct.. there is 2 o2 sensors on a 7A-FE 94 St? One on the headers and one on the up pipe that connects to it. Well on the new up pipe i have, there is no placement on the pipe for the o2 sensor.. but there is a port for the sensor on the new headers i have. With that in mind, how would the car run without the bottom sensor? i've heard it CAN run a little harsh and also that it won't pass emitions which is a concern for me. But if i have the top sensor will it be okay and will it pass? i've also heard something about it not reading the 4 cylinders w/o one, if anyone can explain this to me..

[richee3]

Emissions laws vary from state to state and often even different counties within the state so we can answer whether or not your car will meet local laws and regulations. Generally the upstream O2 sensors take readings and adjust fuel trim and the downstream sensors just tell whether or not the catalytic converter is working (translated: throws a check engine light but otherwise useless.) If you are concerned about passing emissions, then it would be best to keep both sensors. An exhaust shop could take the bung from your old exhaust pipe and weld it into the new pipe.