Fuel air Ratio Meter

[thomas g. warner]

just put a sensor in each side with a switch going to the panel and switch
from one to the other.

>GMCers
>
>OK here I go again. While going through my Summit catalog I noticed
>They had two different meters to measure the fuel air ratio. Both are
>based on an O2 sensor. The one by Elderbrock looks to be a simple
>meter. The one by MSD has a meter with two lights. Red means you
>are running lean and green means you are running rich. Both on you
>are just right. Both are in the $120-130 range. The problem is that each
>of them just has 1 sensor. Now if we had 2 sensors we could read each
>side of the exhaust. I think this would be very handy. We could tell if our
>tuning was off. If we got some dirt in a jet it would tell us we were lean.
>Then we would know why we are running hot. We know that a stoi
>ratio of 14.7 (I think) yields a voltage of 1. Even a couple of cheap
>voltmeters
>would tell us something. Maybe the guy that builds the digi---what ever
>could come up with something for us. The idea is free for the taking.
>Somebody go build us a cool new toy.
>
>Take Care
>Arch
>
>

 

[bartz paul]

Arch:

Westach, http://www.westach.com, 800-400-7024, tells me they have three
different models of a dual air fuel ratio gauge for $68.80.

Paul Bartz

From: warner [mailto:warner]
Sent: Wednesday, October 13, 1999 10:39 PM

just put a sensor in each side with a switch going to the panel and switch
from one to the other.

>GMCers
>
>OK here I go again. While going through my Summit catalog I noticed
>They had two different meters to measure the fuel air ratio. Both are
>based on an O2 sensor. The one by Elderbrock looks to be a simple
>meter. The one by MSD has a meter with two lights. Red means you
>are running lean and green means you are running rich. Both on you
>are just right. Both are in the $120-130 range. The problem is that each
>of them just has 1 sensor. Now if we had 2 sensors we could read each
>side of the exhaust. I think this would be very handy. We could tell if our
>tuning was off. If we got some dirt in a jet it would tell us we were lean.
>Then we would know why we are running hot. We know that a stoi
>ratio of 14.7 (I think) yields a voltage of 1. Even a couple of cheap
>voltmeters
>would tell us something. Maybe the guy that builds the digi---what ever
>could come up with something for us. The idea is free for the taking.
>Somebody go build us a cool new toy.
>
>Take Care
>Arch
>
>

 

[donald w. miller]

Arch,

I copied the following report from somewhere on the WWW about a year ago.
Sorry I didn't save the credits.

Don Miller
75 project
Shenandoah Valley of Virginia

****************************************************************************
**************
O2sensor

I just bought the Edelbrock air/fuel ratio monitor and hears what
I discovered:

Sensor is a Bosch PN E971-9F472-AA .
A lot of numbers stamped on it, but I think this correct Bosch
part number.

I believe this is a standard three wire conventional O2 sensor
though I do not have manufacture's literature.

The "little black box" is nothing more than little and black.
It has a surge suppresser, filter capacitor, a resistor to
control LED brightness, and a LM3914 Dot/Bar Display Driver. The
design is straight from application books with no creativity.

Did I mention the lack of input signal conditioning / filtering
to remove engine / ignition noise?

Given the speed of LM3914 comparators, this is a problem in my
implementation.

The electronics clearly runs sensor in voltage mode drawing only
a 25nA biasing current for LM3914's internal buffer.

The sensor voltage and air/fuel ratio have the following
corresponds:

volts air/fuel Lambda (open circuit)
=====================================
.250 15.0:1 1.02
.375 14.5:1 0.99
.500 14.0:1 0.95
.625 13.5:1 0.92
.750 13.0:1 0.88
.875 12.5:1 0.85
1.00 12.0:1 0.82

>From what I have read in the SAE Transaction pertaining to O2
sensors, this relationship is "bull shit".

I can not believe this mode of operation would let the sensor go
as low as .8 lambda or have this linearity.

I would have expected Edelbrock to use a current mode of
operation.

My next step is to change to current mode operation.

****************************************************************************
******************

> GMCers
>
> OK here I go again. While going through my Summit catalog I noticed
> They had two different meters to measure the fuel air ratio. Both are
> based on an O2 sensor. The one by Elderbrock looks to be a simple
> meter. The one by MSD has a meter with two lights. Red means you
> are running lean and green means you are running rich. Both on you
> are just right. Both are in the $120-130 range. The problem is that each
> of them just has 1 sensor. Now if we had 2 sensors we could read each
> side of the exhaust. I think this would be very handy. We could tell if
our
> tuning was off. If we got some dirt in a jet it would tell us we were
lean.
> Then we would know why we are running hot. We know that a stoi
> ratio of 14.7 (I think) yields a voltage of 1. Even a couple of cheap
> voltmeters
> would tell us something. Maybe the guy that builds the digi---what ever
> could come up with something for us. The idea is free for the taking.
> Somebody go build us a cool new toy.
>
> Take Care
> Arch