Seeing threads about dual exhausts made me wonder about the O2 sensor placement in such a system. An obvious location would be in an X pipe if you add one as all the exhaust is passing through. What would happen if the O2 sensor was in one pipe before an X or Y fitting? Does the sensor measure the absolute amount of O2 or does it compare the concentration with the outside air? Ideally you'd have one sensor in each pipe but could one sensor in one pipe send the correct signal to the ecm? Could the signal be doubled? Halved? This would assume that each bank is putting out the same concentration. I'm thinking for the track it would be easy(?) to just take each down pipe or header to the outside of the car into a couple of mufflers exiting ahead of the rear axle. But I don't know how the O2 sensor would work. ????

 

Just need one sensor in one of the pipes. If there are long tube headers then a heated sensor may be required.

The O2 sensor uses outside air as it's reference. When lean of stoich the O2 sensor measures O2. When rich of stoich the O2 sensor measures the leftover combustible materials.

RBob.

 

I assume the issue with the long tube headers is that the exhaust gas cools too much for the sensor to work correctly and the same would apply if the sensor was too far along the standard system. How can you tell the exhaust is too cool for the standard sensor? Is a heated sensor a direct replacement? What is it connected to to heat it?