Ls1 turbo ms3x external map question

[dtown827]

Hey I am new to this form I have ms3x on a turbo ls1 I just got running and Im sure this has been covered but I can not seem to find it
I am using the onboard map as baro and am trying to run a 3bar external map and I have the calibration data but it is at 0.5 volts -14.70 psi and 4.25 volts 32.18 psi how do I convert this to a 0-5v values if this is a stupid question I am sorry sometimes its the simple things that stump me

[elutionsdesign]

No, that's a good question since most sensors (from the datasheets) don't go to 0.0 volts or 5.0 volts just like yours, odd that the calibration doesn't allow you to put a voltage value in it. So I would do it like this, zero is zero so 0.0 volts would be 0.0 KPa (you want to stay with KPa I assume?) Atmospheric pressure is 14.7 psia or 101 KPa for reference so you get 6.87 KPa/psi. Now your sensor spans 14.7+32.2=46.9 psi or 322 KPa and the voltage span is 4.5-0.5 or 4 volts, that is 80.6 KPa/volt. 80.6 KPa/volt times a 5 volt span is 403 KPa at 5 volts. Put that in the upper range and see if the standing key on MAP value (engine not running) is close to 101 KPa.

[dtown827]

Thank you very much I will try that first thing tomorrow

[BigLou240sx]

Is it true that map sensors must be 0kpa at 0 volts?

I get approximately:
-43 kpa at 0 volts and 388kpa at 5 volts

Changing psi to absolute kpa:
0.5 volts: -14.7 psig = 0kpa
4.25 volts: 32.18 psig = 323kpa
sensor is 323kpa/3.75 volts = 86.1kpa/volt

[elutionsdesign]

No, again if you look at the spec sheets they don't go to 0 KPa but they go low enough, maybe 5 or 10 KPa.

From a random Digi-Key search:

MPXA6400A
20 to 400 kPa (3.0 to 58 psi)
0.2 to 4.8 V Output

[racingmini_mtl]

Is it true that map sensors must be 0kpa at 0 volts?

I get approximately:
-43 kpa at 0 volts and 388kpa at 5 volts

Changing psi to absolute kpa:
0.5 volts: -14.7 psig = 0kpa
4.25 volts: 32.18 psig = 323kpa
sensor is 323kpa/3.75 volts = 86.1kpa/volt

That's correct.

Jean

[BigLou240sx]

Is it true that map sensors must be 0kpa at 0 volts?

I get approximately:
-43 kpa at 0 volts and 388kpa at 5 volts

Changing psi to absolute kpa:
0.5 volts: -14.7 psig = 0kpa
4.25 volts: 32.18 psig = 323kpa
sensor is 323kpa/3.75 volts = 86.1kpa/volt

That's correct.

Jean

sorry for being dense today - which part is correct? It is true that all map sensors start at 0kpa at 0 volts or the 0/5 volt calibration I listed?

[racingmini_mtl]

Your computations are correct. It is not true that 0V is 0kPa since that's not what the datasheet says. You will never see 0V from the sensor but that's not the same as saying 0V is 0kPa. The way you computed the values is how it is done: you simply do a linear extrapolation from the numbers in the datasheet and compute what 0V corresponds to from those numbers (as you did).

Jean

[dontz125]

Agreed. Given that so many pressure sensor datasheets list values from 0.5-4.5v, any chance of getting an option in TS to select the calibration range?

[dtown827]

Well none of the figures I've tried read correct but I noticed in tuner studio under under map calibration it says value at 0 volt (%) not kpa I am using the latest version of tuner studio but under baro settings it does say (kpa) not sure what's going on their

[dontz125]

Which 3bar sensor are you using? Given this is an LS1, I have to wonder if this isn't a GM 3bar sensor, which can already be found in the drop-down lists in TS under [Tools] [Calibrate MAP / Baro].

[dtown827]

It is a 6.6 duramax diesel map sensor under gm 3 bar it reads wrong

[ashford]

do you have a part number from it. a bit of looking and the d max has 3 sensors. the one i found info for has a useable range from 50-330 kpa .25v-4.5v respectivly

gm pn 12215049
info here http://www.daytona-sensors.com/tech_wego.html
and here http://www.daytona-sensors.com/download ... ensors.pdf

[dtown827]

I have come to the conclusion I'm just ditch the sensor I have now and get the aem 3.5 bar