EGOR Output Signal Survey

[Gonyou, Jeremy (.)]

Isn't Circle Track supposed to be a grass-roots type deal?  The system referenced is based off a plain-ol' EGO and costs $1500.  The wide-band system is $3500.  

Jeremy


The July 2001 issue of circle track magazine has
an article on A/F Ratio measurement for power.
Powertrain Electronics Co. 
www.powertrain.net 
AFM1000 wide range exhaust gas sensor
I haven't checked the site yet but the article
looks good.                   Don

> -----Original Message-----
> From:	Bruce Plecan [SMTP:nacelp at bright.net]
> Sent:	Wednesday, May 16, 2001 9:11 AM
> To:	gmecm at diy-efi.org
> Subject:	Re: EGOR Output Signal Survey
> 
> 
> > The first item is the Rcal resistor, the resistor
> > built into each wideband sensor at the factory
> > to cancel differences between sensors.  A simple
> > circuit has been designed to use this feature, and
> > I think it should be included in any group design.
> 
> Definetely
> 
> > Next is the output voltage.  A curve seen in some
> > equipment reads like
> >     A/F             Volts
> >     22:1           3.5
> > 14.57:1         3.0     stoich
> >   10.5:1          2.0
> > A circuit from the list runs about 0.5 V lower
> > than above, but otherwise the same.  My ckt
> > runs 0.2 V lower than above.  I propose we use
> > a design that can produce any of the above by
> > changing a couple of resistors.
> > I have a reason for running mine at 2.8 V stoich
> > instead of 3 V.  The most accuracy is desired
> > around stoich, so my circuit is intended to be
> > dead on at that point.  Calibration and other
> > errors come into effect as you move away from
> > stoich.  To minimize errors, the stoich output V
> > is the same as my reference power supply, and
> > my reference power supply is 2.8 V.  The reason
> > for that is to allow use of newer parts, eliminating
> > a couple dozen other parts.
> 
> Simple is a GOOD thing.
> 
> > My next item is a real time display, a readout.
> > I propose a bar graph with a center LED to
> > indicate operation at stoich.  As operation
> > moves more rich, a column of green LEDs would
> > light forming a bar growing away from stoich.
> > For lean operation, a column of red LEDs would
> > grow in the opposite direction.  The length of the
> > bar would show how far you are from stoich, and
> > the color indicates in which direction.
> >      RRRRRRRRRRSGGGGGGGGGG
> > If we have a readout, how should it be calibrated,
> > and to what resolution?  I would suggest 10
> > divisions in either direction might be good for a
> > dashboard gauge, but up to 20 each way might
> > be better for wide range tuning and operation.
> 
> > What are meaningful divisions?
> 
> This is where we kinda get to too much of a good thing.  IMO, as long as
> the
> results are repeatable, is the number one concern.  If there is enough
> resolution to see that the changes are having the expected results we're
> in.
> For me 10 is fine, but I can see where others would want the 20 flickering
> lights.
> 
>   The A/F to
> > voltage curve is pretty badly curved, but is
> > that even what we want to display?  Here is
> > how I see it.  Imagine we have this box of air
> > and add a bit of fuel.  We get a voltage reading
> > from our sensor when we burn the fuel.  Every
> > time we add a larger amount of fuel (increase
> > injector pulse width), Ip and our Vout shift a
> > proportional amount.  A nice linear function of
> > fuel increase to voltage.  So why is the A/F
> > curve so UN straight?  BECAUSE the function
> > described above IS NOT A/F, IT IS F/A.  So I
> > propose a linear display of the voltage out is
> > really what we need, to relate tuning to output.
> > We can MARK it in A/F, but the markings will
> > not be linearly spaced.
> 
> Mark a high end, and a low end reading and be done with it.  The MAGIC is
> the tuning, not in the display.   Let me rephrase that, knowing where you
> are, and beeing able to see that your going in the right direction is what
> we need.  IMO, too often folks get lost in their tuning.
> 
> > Allright, there is one more factor.  That almost
> > perfectly linear delta fuel to delta voltage
> > relation, shifts as you pass stoich, to a slightly
> > different very linear relation.  I propose that the
> > gain (number of divisions per volt) BE SLIGHTLY
> > DIFFERENT on the 2 sides of stoich.  So now a
> > given increase in fuel will cause the SAME
> > number of divisions movement of the bar, from
> > one side of the display to the other.  Circuit wise
> > this function is almost free.
> >
> > Something else we could add is a switch for
> > free air calibration.  This would normally be
> > off scale, but it would reduce gain to put an
> > indication at 22:1.
> >
> > There is a warmup time approaching a minute
> > for the sensor.  I suggest the display be blanked
> > (turned off) during warm up.   Besides giving an
> > indication of operation, it allows the considerable
> > LED current to be "stolen" from the sensor
> > heater circuit, saving power, heat, and heat sinks.
> > The cost is one transistor.
> 
> I'd agree with that, avoiding a too soon reading.
> 
> > One more output that might be useful would
> > have a 1 volt output range, reading 0 to 1 volt as
> > we moved from 15:1 to 14:1 A/F.  The idea is to
> > look like a conventional narrow band OX sensor.
> 
> YES, YES, YES.
> Using the 0-1 will allow data logging with all the conventional
> scanners!!!.
> C/L can be blocked, and then just info logged to see where things are.
> THANKS
> Bruce
> >
> > All these outputs could exist at the same time, or
> > just put in parts for the ones you want.  I await
> > your opinions on the subject.  Bruce Roe
> >
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