How to: Adjust External Calc: Wideband O2 Setting form my .?

[Steve Bryant]

Paul,
Thats a good idea, because I don't quite know how to construct the formula. Also, if you would, look on the previous page at some of my questions on calculated PID's.

Thanks,

Steve

[John Skiba]

Joe,
For some reason I was thinking about the AEM UEGO AFR meter rather than the TechEdge unit you built. I looked up the data on the web for TechEdge just now http://www.techedge.com.au/vehicle/wbo2/1v5/techo.htm and I do think that you have the formula right. However, soon we'll both have a better idea on this. You'll know right away once you hook the WBO2 output up to your FlashScan interface and log some data. They should agree and you'll be able to tell that right away.

All my best,

Steve

I have the prebuilt. Which formula? The conversion from V or the EFI output?
http://techedge.com.au/vehicle/wbo2/1v5/techo.htm

Joe, I have the same unit and did it as a kit last year. I'm sure we can figure it out and Paul can maybe workup a Tech-Edge V1.5 PID? Paul?
http://techedge.com.au/vehicle/wbo2/wblambda.htm

[Blacky]

Here's a brief "tutorial" on creating calculated PIDs
http://efilive.com/forum/viewtopic.php?t=1142
Paul

[Earl H]

This formula is pretty close:

(x^5)/700 + (x^4)/650 + (x^3)/650 + (x^2)/50 + x/1.06 + 8.41

The Excel image shows actual v's function. That's as close as I can get it.
If you want I can build a calcualted PID for that formula.

That would be greatly appreciated.

[GMPX]

This formula is pretty close:

(x^5)/700 + (x^4)/650 + (x^3)/650 + (x^2)/50 + x/1.06 + 8.41

Never was any good at Maths.

[Earl H]

Would it easier to define a formula to get to line with a better fit by only using the points between 10:1 and 12.5:1 (approx.)? Yeah, I am math-challenged as well. :lol:

...based on the formula:

(x^5)/700 + (x^4)/650 + (x^3)/650 + (x^2)/50 + x/1.06 + 8.41

Here are the changes that I made in the Calc_Pids.txt file, using the Calc_pid construction thread referenced in this post:

# Add slot definitions here
# --------------------------------
# See sae_generic.txt for more information on "SLOT" formats
#
#Units Low High Fmt Expression
#------------ ------------- ------------- ---- --------------------------------------------------------------
*CLC-00-001
AFR 8.41 19.44 .1 "({EXT.AD1}*{EXT.AD1}*{EXT.AD1}*{EXT.AD1}*{EXT.AD1 })/700 + ({EXT.AD1}*{EXT.AD1}*{EXT.AD1}*{EXT.AD1})/650 + ({EXT.AD1}*{EXT.AD1}*{EXT.AD1})/650 + ({EXT.AD1}*{EXT.AD1})/50 + {EXT.AD1}/1.06 + 8.41"

(x^5)/700 + (x^4)/650 + (x^3)/650 + (x^2)/50 + x/1.06 + 8.41


# ================================================== ============================
*PRN - Parameter Reference Numbers
# --------------------------------
# See sae_generic.txt for more information on the *PRN section
#
#Code PRN SLOT Units System Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------
CALC.ELH_AFR F001 CLC-00-001 V Fuel "Ext Wideband AFR"

Does this look correct?

[Dirk Diggler]

What about a linear output like the LM1


LM1: result = volts / .5 + 10

[Blacky]

What about a linear output like the LM1


LM1: result = volts / .5 + 10

That one is built in to EFILive, just display {EXT.AD1} using the AFR units.
You can see the "formula" in sae_generic.txt as this:

#Units             Low          High      Fmt Op     Factor       Offset
#------------ ------------- ------------- ---- - ------------- -------------
*UNM-16-901
 V                 0.0           5.0      .2   /    204.6           0.0
 AFR              10.0          20.0      .2   /    102.3          10.0

This is the basic definition for both {EXT.AD1} and {EXT.AD2} PIDs and it converts the raw A/D value into both voltage and AFR.

Note, the SLOT name of UNM-16-901 defines the raw data as
UNM=Unsigned numeric
16=16 bit data
901=unique sequence number

The raw A/D values comming in from the external A/D pins is a value between 0 and 1023 (using a 10 bit A/D converter) which represents 0 to 5.0 volts.
Due to voltage protection built into FlashScan the highest voltage that can be recorded is 4.8V, but that does not alter the fact that 1023=5.0V

The voltage is defined as:
V=N/204.6+0 where N is the raw digital value in the range 0..1023.

To convert to AFR using AFR=V*2+10, use:
AFR=N/102.3+10

For simple linear values, you can add PID definitions like this to the calc_pids.txt file. Just make sure you use a unique SLOT name and a unique PID name.
You may reference existing SLOTs in sae_generic.txt if one exists that is the same as what you need. Most standard SLOTs are already included in sae_generic.txt.

#Code                      PRN  SLOT         Units            System           Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------
EXT.AD1                    F400 UNM-16-901   "V,AFR"          External         "Wide band O2"

Note: to reference the RAW data values in your PID definition, use the following reserved PRNs:
F400 = {EXT.AD1}
F401 = {EXT.AD2}
F402 = {EXT.EGT}

Regards
Paul

[Earl H]

Blacky,

Got everything to work...thanks!!!

....and thanks to everyone else that lent a hand.

[Blacky]

I found a neater exponential based expression, but EFILive does not support exp() yet!

exp(x)/25 + (x^2)/30 + x/1.2 + 8.41

The next release will have the following functions added:
exp()
log()
log10()
pow()
sqrt()

Regards
Paul