DIY-WB... It's alive...

[John Dammeyer]

Good description but if the Stoich is 100% utilization of the O2 in the
mixture how does the catalyst burn off the HC.  Or is that why the WB
sensors don't do much better than 10:1 AF ratio whereas they can go
considerably further in the lean direction?

John


-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org] On
Behalf Of rr
Sent: Sunday, September 02, 2001 5:15 PM
To: diy_efi at diy-efi.org
Subject: Re: DIY-WB... It's alive...



As mentioned the O2 sensor responds first & foremost to O2. When the
exhaust is stoich, the partial pressure of O2 in the atmosphere will
cause the O2 sensor to generate ~450mV. In order for the O2 sensor to
detect a rich condition, there is a platinum coating on the sensor cone.

Platinum being the catalyst it is will burn off the HC by pulling O2
through the porus cone. This action generates a voltage > 450mV.

BobR.

John Dammeyer wrote:

> I have a question about O2 sensors in general.  On a fuel injection 
> setup where the ignition has a bad miss or even fails for a 1/4 second

> while injection continues,  will the O2 sensor go rich because the 
> fuel isn't being burnt or lean because the O2 is still in the mixture.
>
> That then begs the question.  If the Stochimetric condition is when 
> all the O2 used to burn all the fuel,  how can it ever show a rich 
> condition?
>
> Regards,
>
> John Dammeyer
>
> -----Original Message-----

<snip>


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