O2 sensor pullup resistor values?

[Peter Florance]

Thanks for the reply
On my L jet box there is some sort of 'bias' that provides .45 volts at the
sensor input before the sensor warms up or if it disconnected. I've read
that's how they sense whether the sensor is working or not.
How do they accomplish that?




Peter Florance
81 euro 528i w/ 3.5L


> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Bernd Felsche
> Sent: Wednesday, December 05, 2001 8:16 PM
> To: diy_efi at diy-efi.org
> Subject: Re: O2 sensor pullup resistor values?
>
>
> 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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