[urq] O2 Sensors

Frank de Kat fdekat at sentex.net
Thu Nov 18 18:50:00 EST 2004

Hello All:

Someone was posting that you should get an Air-Fuel gauge that runs off a 
normal o2 sensor to keep an eye on one's mixture. Especially at boost!

Such a gauge has only limited use, as all it can tell you is if you are 
rich or lean. Can't tell you much more than that. (But that's still useful 

Why? Because the output from the sensor is basically in a high or low 
state, with nowhere in between.

See:  http://not2fast.wryday.com/instrumentation/voltage_vs_afr.gif

(From http://not2fast.wryday.com  , down in the 'hardware' section. Lots of 
interesting stuff here!)

For true 'numerical' values of A/F mixture, you need a wideband sensor, and 
the required electrical interface.

I think another useful 'tool' for turbocharged motors is an Exhaust Gas 
Temp gauge. Perhaps a different way of giving one similar information 
(Imminent meltdown of the motor!)

Anyone care to comment on how to make use of EGT numbers?

(A friend had EGT gauge on each manifold of his RX7 motor. It was a very 
useful tool when trying to track down a high speed miss. Easy to tell which 
rotor was dumping!)


Frank de Kat
fdekat at sentex.net
Dundas, Ontario, Canada

(To see the "Rally Pictures")

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