Problem creatingformula for a new item to the .adx Values

[bobdec]

Did a lot of searching but could not find the method to calculate the formula for a new .adx value I trying to add. I have a flash PCM 16188051 $EE files and I'm trying to add A/C Evaporator Temperature F* to the values in the .adx using ADX editor. I have found that the Evap temp byte is Mode, 1 Msg 0, Word 26 on the PCM data stream and in the ADX editor I'm using offset 0X19 (hex) 25 D on the Values, Item creation screen. By experimenting with another program I have found the following.... Temp sensor wire enters the PCM on pin D24, at 0v (ground) potential on D24 the scanner reads 90* F (32.3* C) and at +5V potential on D24 scanner reads 20*F (-6.7* C) . My problem is calculating the conversion equation to display temperature in degrees F. I've understand the 5V/255 fraction but am getting confused on how I factor that into the 90-20= 70/255 fraction needed to convert the voltage to degrees. The other point is the temp display value drops as voltage increases. If so then the fraction in the equation will be negative using start point or 90* F EG:( n* -fraction +90.00) this assumption could be my problem.

[RobertISaar]

the fastest way to work around this with a linear equation is to create a lookup table and only enter two values: 0 A/D counts and it's corresponding real-world value and 255 A/D counts and it's real-world value. Tunerpro will interpolate for any value in-between.

non-linear requires more data points, but essentially the same process.

[EagleMark]

I have found that the Evap temp byte is Mode, 1 Msg 0, Word 26 on the PCM data stream and in the ADX editor I'm using offset 0X19 (hex) 25 D on the Values, Item creation screen.

That's only going to be in a F body Camaro bin file to output to data stream, it's not in a B body Caprice.

26      EVAPTEMP    A/C EVAPORATOR TEMPERATURE
                      DEG F = N/2
                      DEG C = (N - 64)/3.6
 27      ADACPRES    A/D RESULT FROM A/C PRESSURE TRANSDUCER
                      VOLTS = 5N/255
                      PSI = 1.833N  - 14.95

It's 26, but the list starts at 1, should start at 0, so just type in 25 and packet offset will fill in automatically. You got that, not sure what you meant by 25 D ?

[RobertISaar]

25 D seems like it would imply 25 in decimal format, which would be correct.

anyways, if the B-bodies didn't use it, that leaves an easy option to pipe in a wideband AFR signal.

[EagleMark]

Dam we were looking for that awhile ago... we ended up using 26

Cool, I didn't know about D, makes sense when your talking $hex.

[RobertISaar]

i tend to do it myself.... 10h = 16d, stuff like that.

[gregs78cam]

-0.27451 * X +90, I think that should work.