O2 sensors have a vent for reference air. In order to work, an O2 sensor has to have a way of comparing the O2 reading from regular air to that which is in the exhaust. I heard about this myth, wrapping the O2 sensors with aluminum foil to increase mileage. I have not tried it though.
How does the oxygen sensor work?
The sensor works as a result of the varying quantities of oxygen in the exhaust verses the amount in the atmosphere. Voltage is produced by the difference in the two amounts. If the amount of oxygen in the exhaust is closer to the amount in the air, the engine is lean and the voltage is low (under 250mv). If the engine is rich the voltage is high (about 950mv).
My guess on this myth or theory would be by wrapping the sensors they become insulated. The air around the sensor becomes hot and hot air is less dense, having less oxygen molecules. Since the outside air will have less oxygen, it changes the reference point. It must be that the exhaust appears rich under these outside conditions and the computer would actually try to go lean in order to stoich, which in reality it isn't.
Last edited by froggy81500; 07-07-2008 at 12:23 PM.