O2 sensors details
the O2 sensors are not measuring pressure, but they are sensitive to it. (as explain in the Bosch book)
the curve of an O2 sensor is about like this (I hope HTML from Roadfly will not distroy it)
sensivity to O2
|
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|x x
| x x
| x x
| x x
| xxxxxxxxxxxxxxxxxxx
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|_________________________________________________________________ Pressure >>
Basically, when the pressure increase, too much, or decrease too much, you get into an area of the sensor that is not linear anymore.
Then no back pressure, you are on a f(x) ax+b instead of a constant.
That can be problematic to smog ... then you 1st gear and 2nd gear air flow are different at 15mph and 25mph ...
Back pressure increase as well the temperature into the exhaust:
as you can see, you are far from the deam case:
If you want the formula of the responce of the O2 sensor, couple of people published online some nice article. A BOEING dude give a good overview of the science behind. He is speaking about avionic 0O2 sensors, your O2 sensors have more drift than those... enjoy the lecture, it is facinating:
http://ls1edit.slowcar.net/o2volts.htm [3]
Let's see if the graph goes through, if it does not, I ll post a pic.
FrancoisP
