Gen 2 3S-GTE Map Sensor Voltage/Range

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Gen 2 3S-GTE Map Sensor Voltage/Range

Postby entrax » Wed Feb 17, 2021 11:15 pm

Context
The Gen 2 Map Sensor has been attempted to be mapped out for range/volts a few times now, most notably this link being referred to a lot with a calculation.

However, a lot of these calculations gives out a calculation that refers to the boost range which 1) makes it hard to know how far down into vacuum the sensor goes and 2) makes the calculation inaccurate. The second assumption is that it's in BAR or PSI.

What are we looking at?
For reference, we are looking at the 89420-17030 map sensor as fitted in my Canadian 91 Turbo. This should be the same sensor fitted to all USDM turbos.
1) The sensor measures on an absolute scale. The sensor does not know what atmosphere is nor does it measure it.
2) The sensor is in mmHg or cmHg. Either way, it's in metric measure of mercury. The range of the sensor is from 0mmHg to 2000mmHg (or 200cmHg).

This is also confirmed in the BGB with the inspection spec being primarily in the same units (100mmhg per 0.25V change in voltage +/- 0.10V). Every other unit is a conversion.

How to find the range:
Now that you have the range of the sensor, you have to find what is "zero" based on your atmosphere.
In Vancouver as I type this, zero on the gauge is 2.634V. Given this voltage and the inspection spec voltage/pressure change, you can extrapolate that zero on the gauge translates to 1052mmHg, 1.405 bar, or 20.34psi absolute gauge pressure.
You might note that this is way off of the standard atmosphere of 1.013 bar. This is correct, because it is simply where the gauge is calibrated to read zero.

Taking that into account this means the range of the sensor is, you can now subtract your zero calibration numbers from the absolute range to find your calibrated range:
-1052mmHg to +948mmHg
-1.405bar to +1.262bar
-20.34psi to +18.33psi
Since it's also popular to measure vacuum in +inHg: 41.42inHg maximum vacuum

This means that if you're planning to use a standalone ECU and planning to stay under 18psi of boost, there is no need to get a fancy GM 4bar sensor. You can just map the range of the existing stock sensor into your ECU.

Full range of values
With that said, for quick reference this is the range of values in ABSOLUTE PRESSURE per 0.1V of the sensor:
Volts mmHg BAR PSI

5.0 2000 2667.00 38.67
4.9 1960 2613.66 37.90
4.8 1920 2560.32 37.13
4.7 1880 2506.98 36.35
4.6 1840 2453.64 35.58
4.5 1800 2400.30 34.81
4.4 1760 2346.96 34.03
4.3 1720 2293.62 33.26
4.2 1680 2240.28 32.49
4.1 1640 2186.94 31.71
4.0 1600 2133.60 30.94
3.9 1560 2080.26 30.17
3.8 1520 2026.92 29.39
3.7 1480 1973.58 28.62
3.6 1440 1920.24 27.85
3.5 1400 1866.90 27.07
3.4 1360 1813.56 26.30
3.3 1320 1760.22 25.52
3.2 1280 1706.88 24.75
3.1 1240 1653.54 23.98
3.0 1200 1600.20 23.20
2.9 1160 1546.86 22.43
2.8 1120 1493.52 21.66
2.7 1080 1440.18 20.88
2.6 1040 1386.84 20.11
2.5 1000 1333.50 19.34
2.4 960 1280.16 18.56
2.3 920 1226.82 17.79
2.2 880 1173.48 17.02
2.1 840 1120.14 16.24
2.0 800 1066.80 15.47
1.9 760 1013.46 14.70
1.8 720 960.12 13.92
1.7 680 906.78 13.15
1.6 640 853.44 12.38
1.5 600 800.10 11.60
1.4 560 746.76 10.83
1.3 520 693.42 10.06
1.2 480 640.08 9.28
1.1 440 586.74 8.51
1.0 400 533.40 7.74
0.9 360 480.06 6.96
0.8 320 426.72 6.19
0.7 280 373.38 5.41
0.6 240 320.04 4.64
0.5 200 266.70 3.87
0.4 160 213.36 3.09
0.3 120 160.02 2.32
0.2 80 106.68 1.55
0.1 40 53.34 0.77
0.0 0 0.00 0.00

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entrax
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