[Diy_efi] Bernd: UEGO sensor question

bcroe at juno.com bcroe at juno.com
Sat Jul 13 16:31:39 GMT 2002


The Vs output is like a battery, a very low current one.  If 
it were a variable resistance, the pull up or pull down 
resistor value would be critical (which it is not) like the 
pullup on a water temp thermistor.  

The WB "pullup" resistor is more of a current source, 
since the voltage at both ends is controlled.  It can be 
used to detect when the "battery" is not yet operational, 
by shifting the voltage out of normal range.

Bruce Roe

On Thu, 11 Jul 2002 02:26:10 -0700 Perry Harrington 
<pedward at apsoft.com> writes:
> Bernd,
> 
> Am I dense, or does the UEGO require a pullup on the 
> Vs line?  I see in the DIYWB they have a 2v pullup.
> 
> If so that explains your comments and why I was not 
> getting it.  The Vs doesn't produce voltage, it's resistance 
> changes in response to oxygen content.   It's impedance 
> lowers as it leans and gets higher when it richens.   With
> the final impedance being < 100k.

> --Perry

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