DIY_EFI Digest V5 #591

[Eric Fahlgren]

Glenn & Debbie Woodhouse wrote:
> 
> Eric,
> 
> I have dug through the archives and found the Bosch LSM11 curves that relate
> A/F ratio to voltage and temperature (in the rich range) but I have not seen
> the curves for probe resistance vs. temperature, which is the key to using
> this sensor as a wide band meter without incorporating an EGT into the
> system.  If you have this data or know where to get it I would be very
> interested.

Glenn,

A quick scan of the '96 archives gives me this in a post from
Frank Parker <fparker at umich.edu> dated 27 Nov 1996:

> 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 #

I seem to remember seeing a post in the '96 or '97 archives where
someone had scanned and posted the actual Bosch datasheets.  If I
find that I'll let you know.

Eric
-- 
Eric Fahlgren                            Mechanical Dynamics, Inc
efahl at adams.com                          Ann Arbor, Michigan, USA
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org