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My question is whether we can:

a: move some o the resolution on this map down into the rich areas of operation in order to improve the resolution and accuracy there

b: can we extend the range a little??? Can someone find a datasheet or article on these sensors so we can have so idea as to what the reliability of data in that range is?? It would be extremely beneficial to better utilize the stock 02s obviously.

Todd

Well it looks like you could rescale it. You might have some precision up top you can lose and move a point down. Some of the points are nearly in a straight line, like the 7th point. The total graph looks predictable, like a 2nd order poly, you could probably make a pretty good guess as to what it would do lower. Confirming with another known working O2 would probably be a good idea.

I think there are two types of Denso A/F sensors. The older type (Denso refers to it as a "cup type") is used on older new age WRXes. I think the newer type (Denso refers to it as a "planar") is used on STIs. The cup type sensor is only accurate to about 12:1 (assuming 14.5:1 is stoichiometric) whereas the planar sensor is accurate to about 10:1.

I'm not aware of a spec sheet for these sensors, but there is an SAE paper which describes the planar sensor and compares it with the cup sensor at http://www.denso.co.jp/DTR/vol7_no1/dissertation5-i.pdf. As you can see, the sensor's signal is current flow. I believe a sensor controller subsystem in the ECU translates that current to a voltage which is what the main ECU processor sees.

Here's a figure from that paper which shows the response curves of the two types of sensors:

The cup type curve sems to make sense with the map off a WRX that I had above.

Have we found this map on STIs yet??? Maybe there is scaling which we can use on a WRX w/ a sensor off an STI.

Todd

Hitokiri wrote:The cup type curve sems to make sense with the map off a WRX that I had above.

Have we found this map on STIs yet??? Maybe there is scaling which we can use on a WRX w/ a sensor off an STI.

Todd

How about replacing it with a wideband instead. Correct me if im wrong but if you can scale it and you have the specs for the sensor it is possible in theory right?

ooooo...

Good idea!

Freon wrote:Good idea!

I found the datasheet for the Bosch LSU4.2 Planar Wide Band Lambda Sensor which I believe is what my Tuner Pro uses but im way out of my league in understanding how the sensor works or if it would work at all.

Found alot of info over on Megasquirt.

http://www.megasquirt.info/PWC/LSU4.htm
http://www.megasquirt.info/PWC/PWC.htm
http://www.megasquirt.info/PWC/wire.htm

Datasheet
http://wbo2.com/lsu/Y258K01005e03mar21eng.pdf

there would on;y be the possiblity of replacing the rearo2 with a wideband. The planer and cup sensors use current rather than voltage.

Therefor I doubt retrofitting a wb would work.. But putting a planar sensor in and rescaling for it surely would!!!!

now. the question is. Does the vup type sensor used in the standard WRX use the same control circuitry as is needed for the planar sensor. If so, everyone can have a cheap wideband!!!!!

John. Do you have part numbers for the different sensors? or have any idea when Denso switched over?

do non DBW STIs have the planar sensors? I was just looking at some 03+ JDM STI etc, that seem to have the same sensor scaling as the WRXs wth aparently the cup type sensors.

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what rom images should we look at in finding out the scaling for a planar sensor???

John do you have any ideas??