O2 sensor question

[Garfield Willis]

On Fri, 24 Mar 2000 03:02:33, "Mike (Perth, Western Australia)"
<erazmus at wantree.com.au> wrote:

>At 11:07 AM 22/3/2000 -0800,  garwillis at msn.com (Garfield Willis) wrote:
>
>>For those unfamiliar, "EGOR-the-module" is an interface for a
>>current-pump-style NTK-Honda 5-wire wideband sensor, basically it's a
>>black-box with pins, around which you'll be able to build a
>>WOT/wideband-O2 engine manager; and "EGOR-the-meter" is a hand-held
>>precision AFR meter with large digital and bar-graph display (and an
>>analog out for logging, of course), useful for tuning/cal work.
>
>Are there any specs for the sensor ?
>
>I'd like to integrate the display into my own equipment,
>
>Tah

Hey, one thing I gotta know...what's this "tah" interjection you often
use, mean in WestOz? Is it like a grin, or a "heh heh" or "hee hee" like
we do in the States? I've never seen it before and kinda appreciate the
general Aussie verbal style, so I had to ask. If it's difficult (or
embarrassing) to convey via public typing, don't sweat it.

Anyway, on to your question. This has been explained before, but this
type of sensor (the Honda-NTK sensor is one of the so-called
"current-pump" types) REQUIRES a special sort of interface electrics to
go with it. It's not merely a passive sensor like the older "Nernst" or
switch type sensors, which just put out a voltage you read. There's a
little pump inside these new sensors that squirts oxygen ions into (or
out of) another measurement cell, in an attempt to balance out excess or
depletion of oxygen in the exhaust gas. This clever trick is what allows
these sensors to be so "linear" and good as O2 measurement devices, but
makes operating the sensor more complicated than the older type.

EGOR *is* that special interface electrics. If you want to roll your own
display, you could use just an EGOR-module, and build your own
instrument around that, but when you see how snarky and inexpensive our
EGOR-meter is going to be, you'll probly just go for that instead.

This discussion allows me to add another comment/recommendation about
how to plan for using these sensors. Ya know, they're all still pretty
spendy, even with the Honda sensor available with a goodly discount over
the net for slightly less than $100, that's still a pretty decent
chunkOchange for "consumables". I would think twice about planning on
having such a sensor left in the exhaust ALL the time, and part of your
normal everyday panel meters. Everybody knows that rich running, oil
burning, and lead mix all contribute to shorter lifetimes for these
sensors. Add to that the fact that any heated sensor has a VERY hot
ceramic bit in them that can be instantly fractured if clobbered by a
errant drop of water from a cold exhaust system. All it takes is
condensation in the wrong place, a (perhaps unbeknownst to you) poorly
chosen placement of the O2 bung, and all these things may put you in the
position of test engineer where the supplies of sensors is paid for out
of your own pocket. The auto mfgs. found out about those types of
mistakes and paid for them (usually, hopefully) during engineering
trials. You might want to avoid those costs if possible.

Sure, you're gonna go for it if you're planning on a WOT/wideband ECU,
because you don't have any choice, and you need that WOT tight control
to get your track times down, or whatever. But if you're using it for
tuning and tweaking your open-loop fuel maps in your EFI controller from
time to time, I'd suggest you consider it a hand-held instrument that
you use via a tail-pipe probe, and you only expose the sensor to these
attendant dangers whenever you need to be performing those kinds of
measurements. On the front panel of the EGOR-meter right below the ON
switch, you're gonna see a litany of cautions (like a pilot's checklist,
if you will) to help you avoid damaging the sensor, just because the
bloody things still cost $100, and in most places that can still buy a
nice dinner for two. But of course, it's everyone's choice. I'm just
trying to point out some realities of the situation. Everything possible
has been done to keep the deployment of this cool measurement technology
as absolutely low-cost as possible. So the clients we're targeting we
just ASSUME will want to be very careful with their sensors and baby
them. But if your gameplan (e.g., WOT controller) or robust pocket
change allows it, sure go for a permanent wideband sensor in your
exhaust full-time, and use an EGOR-module to interface that sensor to
your own custom electrics. That is one of the uses it's intended for,
except we think mostly for both economy and appreciating the finer
things in life, if you're not building an engine manager, you'll
probably find our meter irresistible. :)  But like I said before, both
the module and meter are going to be very affordable, so the choice will
be yours.

Gar


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