Lambda Sensors....

[Frank Parker]

> My understanding is that the current oxygen sensor used on mass 
> produced vehicles are only good to tell you if you're at stoich.
> Other wise it can tell you that you're rich or lean, but it can't
> tell you how much.  If it did, then the ECU can just make adjustments
> constantly and you won't ever need to go open loop unless something
> fails. 

That is essentially true but it does not preclude you from getting
pretty decent info from the sensor since for a particular application,
they are very repeatable and soon you learn, with a Gtech Pro for example,
that the car runs best at a certain O2 voltage. Buick GN guys do this all
the time with pretty good results. Plus you can tell alot from collecting
data rapidly and plotting. A OTC scanner, especially with the older car
computers, makes it hard to see trends. A recent vtec turbo project was
pretty easy to tune by collecting O2 voltage @ 100 times/sec and plotting
vs fuel press. This does have to cost alot either as there are cheap serial
port data collection boxes or even Radio Shack data collection voltmeters
for < $100.

> 
> Now, I don't understand the difference in a $5000+ Horiba oxygen
> sensor and a $30 Bosch for regular cars.  I mean, I know a good
> sensor has a wide range and can tell you the exact A/F ratio.  But
> why are they so expensive.  Please, get techical if you have to.
> I'd love to learn more.


The main thing to know is that the Horiba is a repackaged NTK with the
price doubled for a couple of decals. Horiba has marketing rights for
NTK UEGO sensors in the USA. The NTK/Horiba is an excellent sensor but
can not be read with a voltmeter but needs the interface box to supply
a constant current to its dual cell design. The Bosch LA-2 meter uses the
LSM-11 sensor, which alone may be purchased for about $140. It is a highly
modified std O2 sensor made for accurate a/f measurements even in rich 
range. Much more in an excellent book by Ronald Jung, available from SAE,
called "Automotive Electronics". LArge chapter on O2 sensors and all
other auto electronics. Can get ISBN # of there is interest of group.
Some of the changes in this sensor are the reduced flow( no slots on side)
and the better tolerence to which it is made.



> When I first posted to the list couple of weeks ago I asked about
> the LambdaView (LV) from C&M Racing Systems.  Frank Parker from the list
> told me last he heard it was not ready yet.


Still not ready I do not think. HAve not talked to Mike recently but he
is a pretty busy guy and it is not a top priority. His idea was to also
use the Bosch LSM-11 sensor. BUT all hope is not lost. I was working on
a design and have curves from Bosch when I found out that Mike Licht of
Modern Muscle, Maker of some pretty nice stuff for GN guys, is very close
to a meter using LSM-11 sensor that will sell for about $800 and be the
equivelant of the $5000 Bosch LA-2.
I talked to him this week and they expect to start production next week.
For those interested, you may call Mike @ MM at 810-754-0261. That is in 
MICH. Reference this list.

The advantage of this sensor is that its voltage curve will match a std
sensor and thus the car will run on it. Thus you do not have to add a 2nd
bung likr you would with a NTK UEGO sensor. Just replace std factory sensor
with the Bosch LSM-11 and tap off in parallal and connect both to car cpu
and the external a/f meter. External a/f is high impedance like a digital
voltmeter and will not affect the car cpu.

Frank Parker
 


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