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

[Mark S. Riley]

Stoich is not 100% utilization of the O2. Stoich is the point at which the
gas emissions are the lowest and highest. I'll have to break out a book,
can't remember  the exact numbers but stoichimetric is not neccessarily
where you might want to run your engine. But it does give the lowest
emissions there. So, that's why the all the OEM's are so concerned with it.
And that's why O2 sensors and all fuel air meters currently used are so
concerned with it.
As for the range 10:1 to approximately 22:1 is not really where gas engines
run. Quite frequently meters will read over a far larger range than what is
neccessary or wanted. I think the fact that the sensor will read to 20/22:1
is like the air conditioning freon sniffers. I have one of those that is so
sensitive, the manufactor claims it will detect a 1 OZ. per year leak. Any
idea what that kind of ratio that might be, 5 million to 1 or something
ridiculous. Gasoline engine will run fairly reliably in the range of 11.5:1
up to 16.5:1. Numbers that low don't make max power and numbers that high
can't make much but it will run. I don't think anyone has every come close
to 100% utilization of the O2. Top Fuel might be the closest but I still
think they have a long way to go to 100%. later, Mark

----- Original Message -----
From: "John Dammeyer" <johnd at autoartisans.com>
To: <diy_efi at diy-efi.org>
Sent: Sunday, September 02, 2001 10:21 PM
Subject: RE: DIY-WB... It's alive...


> 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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