Re: Odp: Leading guestions+1

[Ludis Langens <ludis@cruzers.com>]

jamesc@venturalink.net wrote:
> 
> Why would you need a lambda interface to amplify the Oxygen signal?  My research
> found O2 output straight into a 10 bit A/D has enouph resolution to determine
> not only stoichiometric or not, but a full range of A/F ratios.

First, GM only has an 8 bit ADC.

Second, the interface chip allows a differential input signal.  In other
words, it senses the ground voltage at the sensor.  The ground voltage
in the ECM might be different, and/or might be noisy.

Third, the interface provides enough of a bias to go to a safe value
when the sensor is cold, or there is a circuit break.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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