info about Honda UEGO sensor

[Frank Parker]

> Has same wires and colors as the NTK $600 sensor..
> 
> Same compensating resistance in the plug too...
> 
> The UEGO body markings are the same as the one from 
> Horiba ($900+) MEXA analyzer ..
> 
> Honda wiring diags from Civic VX show same ckt. annotations
> as the NTK fax I received .. 
> 
> For heater:     orange  Vh+
>                 yellow  Vh-
> 
> For Sensor:     red     Vs+
>                 black   Vs- / Ip-
>                 white   Ip+
> 
> Now, all we need to do is to build a DRIVER circuit
> and we will have the DIY_EFI $200 UEGO sensor...
> 
> Vs. $1000 from NTK, or $2500 from Horiba ...
> 
> Maybe $250, with a PIC and a nifty display addon ;)
> 
> Jim
> ----------------------------------------------------------
> 
> Jim, are you still here?  Any other comments about this sensor?
> 
> --steve

Yes, the Honda sensor seems to be the same as the NTK manufactured sensor
except for where the cal resistor is. Horiba has marketing right to this
sensor in the USA foe air/fuel measurement. They slap on decal and charge
twice as much. This UEGO sensor is a back to back O2 cell with a VERY
complex constant current and sensing electronics. Nobody so far to my
knowledge has been able to clone the sensor box. The sensor is easy but
it is not a voltaic cell like the std sensor and you can't just read
its voltage. If you call NTK here in Farmington Hills, MI and sign a
written statement that you won't use for air/fuel measurement, they will
sell you the sensor for $600 and box for $400. Otherwise its $2400 from
the rip-off guys @ Horiba.

BUT there appears to be another solution- the Bosch LSM-11 sensor as used
in their LA-2 $5000 air fuel meter. The sensor alone is about $190. I just
purchased 3 more at that price from a Bosch distributor. I have the cal
tables on this sensor and I also gave copy to Jim. We started to design
an interface for this sensor as it is much simpler. This sensor has the
BIG ADVANTAGE that its voltage curve is a very close match to a std sensor
as thus you can just replace the std sensor in your car with the LSM-11
and then car will run fine on it. Then can hook up your a/f interface box
in parallal and read out a/f ratio. The main thing to solve with this sensor
is the large temperature correction. The idea was to use a PIC as a
controller. Figure out a math function ( 3rd order or so) to match the
std S shaped curve, then use the temp as an offset function in the
controller. The internal resistance of the sensor changes from about
10 ohms to over 100 ohms and is a indication of the temperature.
To give you an idea of the shift with temp, note the following:

          OUTPUT      650 deg       750 deg        900  deg

	830 mv	      13.94        13.23           12.02

As you can see if you are tuning for max power, there is a big difference
between 13.9 and 12.0 air/fuel at a fixed 0.83 volts.
All is not lost, Mike Licht @ Modern Muscle here in Detroit(810-754-0261)
is in final test stages of a a/f meter that uses this sensor. Will sell
for $800 including the sensor. That is why Jim and I stopped work on our
design and are waiting for the MM meter. Interested parties can call
Mike @ above #

AND if the MM meter falls thru, one can always use the bare LSM-11 sensor
by measuring it's voltage and also the temp and using the Bosch data to
manually calculate the a/f ratio.

This may be more than you wish to know but should be of interest to this
group especially since as recent discussions have shown, even MAF cars
need to "tune in" the a/f ratio.

Frank Parker
fparker at umich.edu
313-763-3470 ph