what is the exact purpose for 2 o2 sensors

[nosv6]

I have a 95 3.4 and there are two oxygen sensors and i was pondering splicing the two together so i can install an exhaust temperature guage in the o2 sensor slot. Has anyone installed an exhaust temperature guage. May sound stupid but can't make sense of 2 o2 sensors.

[sped214]

Having 2 allows the PCM to compare the emissions both pre and post cat to determine the efficiency (and existence) of the Catalytic converter.

[nosv6]

I am confused since both of my O2 sensors are in the exhaust manifolds, i.e. one on each side, before the Cat converter. Please clairify. Thanks

[Backfire]

<blockquote>quote:</font><hr>Originally posted by sped214:
Having 2 allows the PCM to compare the emissions both pre and post cat to determine the efficiency (and existence) of the Catalytic converter.<hr></blockquote>

The two O2's you are refering to are not found on the OBD-1 3.4L cars. They only have one sensor in each manifold, nothing down by the cat.

I don't know how removing one of them would work. The PCM would loose the ability to differential between the two banks of cylinders. It might prevent you engine from operating as close to an optimum A/F mixture as it could. For example, if something goes wrong on the side where you removed the O2, the PCM won't pick it up through the O2 A/F reading like it normally might. Never heard of anyone replacing their O2 in the manifold on any car, I have only heard of sims used as sped214 mentioned on OBD-2 cars.

You could probably have an exhaust shop weld in a boss for you to mount the temp sensor in and still keep the O2's.