Correct A:F Ratio @ WOT?

[Jon Davis]

I don't want to measure the output of the O2... I can do that with my DMM. I
am going to make a circuit that adds an offset to the output of the sensor
to tell some lies to the ECU. I wanted to know the esr so I could make the
output of my offset circuit mimic the sensor better. Guess I'll just shoot
for 100k and call it good enough. When I measured the output of my O2 during
closed loop cruise, the average was .56 V which seems a little rich.

Jon Davis

----- Original Message -----
From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, October 02, 2001 4:50 AM
Subject: Re: Correct A:F Ratio @ WOT?


> Jon Davis tapped away at the keyboard with:
> > I have wondered about real vs. indicated AFR... some mods on my
> > car seem to do real well for about a week, but the power slowly
> > disappears over time. I wondered if I was changing the combustion
> > and screwing up the self-learn in my ECU. I thought about making a
> > circuit with a variable offset on the O2 sensor, to tell some fibs
> > to the ECU and see what happens. Anyone know the esr of an oxygen
> > sensor offhand, around 100k?
>
> It may be "broken" if you try to run a resistance measuring current
> of any magnitude through it for any length of time.
>
> One measures the output voltage into a high impedance (>1Mohm).
> The ECU is probably looking for the switching voltage about 0.45
> volts, which is equivalent to stoich.


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