Close:

(19.98-10.0)/255*x + 10.0 = 0.03914*x + 10.0

 

Your formula would be:

0.03914*x + 10.0


That's assuming that a reading of 255=4.99V

Edit: mrfred just beat me to it

 

Ah I meant to add the 10 in there, just forgot. Thanks guys, much appreciated.

 

By the way what does the 255 value represent?

 

The voltage signal from the AFR sensor is digitized by the ECU. The ADC converter in the Evo ECU can digitize a value up to 5 V, with 5 V = 255.

 

Cool, thanks for the explanation

 

I'm logging the Uego now through MUT12 but, the response rate is REALLY slow plus the log doesn't match what the gauge is showing me? Any suggestions??

 

have u got 10 and 19.98 right?

 

I think I have it right, not sure exactly what/where you mean?? I used the values 10 and 19.98 in the formula to determine the correct Eval formula but, where else would it be used?

I did notice from looking over the EVOScan .xml file that the "External Wideband A/F Ratio" line differs from the new entry I added for this patch to read the wideband hardwired through the rear O2 sensor ADC.

The last bit of the entry for the "External Wideband A/F Ratio" line reads:

GAUGEMAX="60" ChartMin="0" ChartMax="60" ScalingFactor="10"

The entry for the hardwired wideband entry reads:

GaugeMax="22" ChartMin="0" ChartMax="22" ScalingFactor="1"

That is the only difference I see. Could this be the issue in difference between what the Uego gauge is showing versus what is showing in EVOScan from the Uego O2 sensor?

 

See the reference sheets I have here:
https://www.evolutionm.net/forums/6384799-post94.html
(the have the values and formula built in for the UEGO)

You may want to adjust your values slightly if you can log both serial and analog.

 

Good info thanks. I assume than this means I need to adjust the formula I came up with of 0.03914*x + 10.0 by 0.14423 (I rounded it off)? Next question would be do I add or subtract that figure from the formula?

 

Hello Mrfred

instead of using the pin of the rear O2, is it possible to use the pin 64 in the Evo IX?

Pin 64 is declared as ADC input 0-5V with 5V=255, and it seems unused in the code.

How would your patch be changed for that?

Thanks

mlocatel

 

whats wrong with the rear02? why dont you want to use it?

 

Basically nothing, but I'm not sure it is free in my version 88840017.

If we could use the ADC which is not occupied it is safer.

I'm not 100% sure that my EVO doesn't have a rear O2 though

 

Pin 64 is used for tephra's map switching.

Its not hard to figure out whether pin 73 is used for anything. Best way would be to have a look in the factory service manual for your car. Second best is to pull the ECU plugs and look to see whether a wire runs into the connector hole for that pin.