How the Formula in the EIO section Works

the Formula in the EIO(AUX) section is called a transfer function
it works by you teling it a step value and then telling it an offset from 0

things you eed to know to figure out the formula for you device you are trying to use in the EIO section

A) Voltage Maximum of the Device being used
B) Value Represented by the (Volts=0) of the Device being used
If the device doen not output 0 Volts then you need to used math to figure out what value 0 volts would equal.
C) Value Represented by the Voltage Maximum of the Device being used



then its (A)/(C-B) +B



Example #1
Wideband O2 Sensor (LC1)
0 Volts= 7.35 AFR
5 Volts= 22.39 AFR

Volts Max = 5
AFR represented by 0 Volts = 7.35
AFR Max = 22.39

so 5/(22.39-7.35) +7.35
or in our EIO Formula
Volts/ 0.3324 + 7.35




Example #2
Autometer P255 Fuel Pressure
0.5 Volts= 0 PSI
4.5 Volts= 100 PSI

to get back to 0 since we do not know it yet

(4.5-0.5) / (100-0) = 0.04
0.5/0.04 = 12.5

0 volts = -12.5 PSI
4.5 Volts = 100 PSI

Volts Max = 4.5
Fuel Pressure Represented by 0 volts = -12.5 PSI
Fuel Pressure Max = 100 PSI

(4.5)/(100-(-12.5)) = 0.04

Volts/ 0.04 + (-12.5)

With my new NGK/NTK wide band, .5V=9.00 afr, 4.5V=20.00 afr

When I use my data, I come up with (4.5-.5)/20-9=.045
.5/.045=11.11
0v=11.11
4.5v=20
4.5/(20-11.11)=..506
volts/.506+11.11


What am I doing wrong?

Instead of the transfer function just use the list instead. It's a simple define 0.00v, xx.xx afr and 5.00v, xx.xx afr. Cuts the figuring out the equation out of it.

Thanks, but they did not provide a list, only a graph and the .5V and 4.5V AFRs. My problem stems from trying to figure the 0V AFR. It is obviously not 11.11 if .5V is 9.0 AFR

http://i36.photobucket.com/albums/e1...psd35f3010.jpg

When I first entered my two V/AFR into the list in scanner, instead of putting the .5 volt afr into the .5 v column, I changed the first entry from 0 volts to .5, and tried entering the 4.5 volt afr somewhere else wrong, too.
When I did it the right way, it worked. Thanks.
http://i36.photobucket.com/albums/e1...ps5d0ff10e.jpg

what was the right way? I see two different tutorials

http://www.hptuners.com/help/demos/custom%20EIO.swf

When I use the tutorial I get this:

(4.5-.5)/(20-9)
4/11 = .3636

SO I use that in the Volts box .3636 + 9

Is that correct? Its done per the tutorial.





and this thread and they seem to be different ??

I think I just responded to your other post :)

The old AFX box would run 3 different voltages at startup representing min, max, and stoich voltage output. I don't know if the new ones do that, but if they do, it gives you a really easy way to check your transfer function to see if its right. You can also log the voltage value from that EIO input directly if you want to validate that it really is .5 and 4.5V for min/max as read by the device.

Must have had a digit wrong or something... installed 2.24 and used the new PID and it seems to work fine now

So this is the same for lamda? The 10-11 Camaro V6 tables are lambda, not AFR. So would this be correct?

Wideband O2 Sensor (LC-2)
0 Volts= .65 Lambda
5 Volts= 1.65 Lambda

Volts Max = 5
Lambda represented by 0 Volts = .65
Lambda Max = 1.65

so 5/(1.65-.65) +.65
or in our EIO Formula
Volts/ 1 + .65