O2 sensors readouts

gene

New member
Sep 29, 1999
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Brings up a point I was going to make,

You do not need a dash meter to read these O2 sensors. You could use a
digital voltmeter like I show on my instrumentation page. I think you can
read this voltage on any meter with a high input impedance like a digital
voltmeter. Don't use your old analog meter and don't try to test them with
an ohm meter.

If you look at the calibration references I have on my web page, you will
see these sensors are voltage generators and the standard ones are designed
to provide .45 volts at the optimum air/fuel ratio of 14.7 to one.

They don't output voltage until they are up to temperature.I am not sure
just how accurate they are since they live in a hellish environment. They
have a S curve at the optimum voltage, which says the voltage output
changes very quickly at the optimum point. This is why the EFI computers
vary the mixture back and forth to go through this active region.

>From what I read they are somewhat fragile and they often fail from :
leaded fuel
shorting the output
after engine overhauls
stressed mountings
low resistance meters

To debug EFIs', most shops change this first then go looking for other
problems.

gene

>
>I am wondering how many might be going to the GMC Western States Roundup
>in April 24-29. If there are a number planning to go and if one person
>could get them in time before leaving home, it would save Alan alot of
>trouble in the shipping. We will be there, however we will be away from
>home from the beginning of April. I f there was an interst in this I
>would be interested in such an arrangement.
> One other thing- Are these sensors generic as to electrical sensitivity
>so they will work for any dash gauge? In other words is there any
>question of matching them to any particular gauge?
>
>Alan I will give you all the details you need as soon as I sort out what
>i want.
>
>Claude
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
also the voltage goes from abot .1volt to close to 1 volt, so the swing in
voltage is generated from the fuel air mixture. Anyone can install one and
read the voltage at various times can see this swing. The voltmeter will move
up and down. The air /fuel gugaes we installed run up and down and the
mixture is made richer or leaner by the fuel injection.
al

> Brings up a point I was going to make,
>
> You do not need a dash meter to read these O2 sensors. You could use a
> digital voltmeter like I show on my instrumentation page. I think you can
> read this voltage on any meter with a high input impedance like a digital
> voltmeter. Don't use your old analog meter and don't try to test them with
> an ohm meter.
>
> If you look at the calibration references I have on my web page, you will
> see these sensors are voltage generators and the standard ones are designed
> to provide .45 volts at the optimum air/fuel ratio of 14.7 to one.
>
> They don't output voltage until they are up to temperature.I am not sure
> just how accurate they are since they live in a hellish environment. They
> have a S curve at the optimum voltage, which says the voltage output
> changes very quickly at the optimum point. This is why the EFI computers
> vary the mixture back and forth to go through this active region.
>
> >From what I read they are somewhat fragile and they often fail from :
> leaded fuel
> shorting the output
> after engine overhauls
> stressed mountings
> low resistance meters
>
> To debug EFIs', most shops change this first then go looking for other
> problems.
>
> gene
>

> >
> >I am wondering how many might be going to the GMC Western States Roundup
> >in April 24-29. If there are a number planning to go and if one person
> >could get them in time before leaving home, it would save Alan alot of
> >trouble in the shipping. We will be there, however we will be away from
> >home from the beginning of April. I f there was an interst in this I
> >would be interested in such an arrangement.
> > One other thing- Are these sensors generic as to electrical sensitivity
> >so they will work for any dash gauge? In other words is there any
> >question of matching them to any particular gauge?
> >
> >Alan I will give you all the details you need as soon as I sort out what
> >i want.
> >
> >Claude
> >
> Genef -- 77PB/ore/ca
> GMC MOTORHOME INFORMATION
> mr.erf
> http://www.california.com/~eagle/
 
You are doing well but
Major failure modes that you missed
Silicone contamination, yes that RTV that people love to glob on,(it kills)
Impact shock
Poor connections, especially universal applications, user spliced wires.

>Brings up a point I was going to make, You do not need a dash meter to read
>these O2 sensors. You could use a digital voltmeter like I show on my
>instrumentation page. I think you can read this voltage on any meter with a
>high input impedance like a digital voltmeter. Don't use your old analog
>meter and don't try to test them with an ohm meter. If you look at the
>calibration references I have on my web page, you will see these sensors are
>voltage generators and the standard ones are designed to provide .45 volts at
>the optimum air/fuel ratio of 14.7 to one. They don't output voltage until
>they are up to temperature.I am not sure just how accurate they are since they
>live in a hellish environment. They have a S curve at the optimum voltage,
>which says the voltage output changes very quickly at the optimum point. This
>is why the EFI computers vary the mixture back and forth to go through this
>active region.
>From what I read they are somewhat fragile and they often fail from :
> leaded fuel
> shorting the output
> after engine overhauls
> stressed mountings
> low resistance meters
>
>To debug EFIs', most shops change this first then go looking for other
>problems.

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