O2 sensor pullup resistor values?

[Bernd Felsche]

Peter Florance tapped away at the keyboard with:

> Anyone have any idea of typical ECU pullup resistor (to ~ .45V)
> values for O2 sensors inputs? I'm trying to make a analog circuit
> to average 2 sensors for my L-jet box and would like to
> incorporate it in the front end of the buffers.

The "pullup resistors" would be infinite. The sensor is a voltage
cell; it provides a voltage. Attempting to bias the sensor can cause
damage to the sensor. If you want to level-shift or add/average two
sensor inputs, the easiest solution is to use op amps to perform the
task. Their high input impedance ensures minimum current draw and
sustained operation.

> Also interested in any comments regarding averaging O2 sensors for
> dual exhaust systems and idle performance (in line 6 engine)

Before you go and build a simple adder circuit however, look at the
response curves and the consequences of what will happen if one is
receiving rich and the other a lean mixture. The ECU needs then to
see a constant switching between the levels for correct operation.

-- 
Bernd Felsche - Innovative Reckoning, Perth, Western Australia
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