O2 Sensor Extender?

[cooltechie]

Originally Posted by hockeyadc

Do the O2 Sensor extenders really increase your mpg?

This is how Oxygen Sensors work, regardless of what people are saying all over the Internet (they are all saying it because they heard it from someone who heard it from someone who heard it from someone else but no one really knows).

Oxygen Sensor "only" measure the amount of "heat" coming out of the pipe. As the Oxygen Sensor heats up due to a reach mixture (above 600f) starts to produce a small voltage (from 100mv in some cases up to 3v). Any time the ECU reads below 450mv it will take it as the engine running "lean", why? because the air coming out is so cold (due to high oxygen) that the sensor will not heat up to high, giving a low voltage output.
When the ECU compensates by giving more gas the engine starts to run more reach, making the output gases hotter and therefor heating up the OS sensor who then starts to produce more voltage. The ECU will do this until the output voltage will average to 450mv (perfect mixture according to the CPU programming).

Now, to the point that I am trying to make. If you install an extender, this will pull the OS a bit out of the pipe, less hot gases will go through it (if any) making the OS work a bit colder ... yes, you guessed it, it will output less voltage telling the ECU that the output is high in oxygen (or at least that's how the ECU will see it). The ECU then will try to compensate by giving gas and yes, you guessed it again.... that does not sound like it will be saving you any gas, now does it?

OS extenders => "Bad Idea"