External MAP and SD Calculator transform + maths issue

[Ranger Coyote]

I'm trying to fine tune my SD tables. The problem I'm having is the AEM Map sensor is measuring pressure and vacuum and the SD calculator wants just positive values. I tried to add the Barometric pressure value to my AEM but when I set that as my axis it logs really slow. How am I supposed to do it and not lose accuracy by using my calculated barometric pressure pid?

Thanks!

SDCalc.jpg
externalmap.hpl

[murfie]

Log the sensors voltage. Convert voltage to absolute pressure using a math.
or
Just add the value your MAP sensor is reporting and not the PID, MAP doesnt change that much.

[Ranger Coyote]

Thanks Murfie! I found this sheet when I was trying to figure out how convert voltage. Has the formula right at the top

AEM.jpg

[murfie]

X is voltage

Grey is formula for units in KPA

Blue is for units in inHg

Orange is for units in PSI

x is voltage.PNG

Clicking this unit under SD changes it, and the units in the SD calculator. I like inHg because thats what fords actual formula uses. airmass to inHg or viseversa.

SD calculator units.PNG

SD calculator units1.PNG


SD calculator units3.PNG
SD calculator units2.PNG

[Ranger Coyote]

I changed everything over to inHg and used the formula from your spreadsheet to convert the voltage directly. Appears to be working!! I'll remove some of the extra pids and go try to fill in my SD table and see how it works.

aemworks.jpg

Drive Log with updated formula

externalmap2.hpl

Thanks Murfie!

[Ranger Coyote]

Update: It works, my calculated map now matches my actual map almost perfect... no more weird fuel spikes and stuff... THANK YOU MURFIE!

[onefastt]

Not sure if its correct but I have the 30-2130-75 sensor. I used the transform function (Input/.02986)+ -14 + output. The way i did the math was convert 75 psi to inhg 152.70 and divided 4.5/152.702 which is .02986 i had to subtract 14 to get the inhg to match barometric. Is this the correct way to do this Murfie or should I do it another way?

[murfie]

I say just log the voltage as is, then use a user defined math. You are not stuck having to divide the input.
You can right click the MPVI channel and select transform. HPT has a few sensor transforms already in there for you. they might not be absolute, in which case you have to change the offset to reflect absolute.
You can always right click the channel and change the unit from these predefined transforms.


transform.PNG

[onefastt]

that transform only works for PSI i tried to change the unit of measure to INHG and it didnt read map correctly.

[murfie]

for the AEM 30-2130-75 this is what I got. I did the inverse to get the values you would use in the channel transform. you can see the divisor came out the same as HPTs predefined, but the offset is -14.7 more(-24.075 compared to -9.375), so it is not absolute as its unit indicates.Always good to just do the math yourself so you know the values you are getting are correct.

AEM 75.PNG

user defined transform:
volts / .026195 + (-19.088)= should be the transform to get your output in inHg absolute pressure.

[onefastt]

Thank you Murfie that Transform worked.