Red21
Well-Known Member
Some simple tech info I gathered from the net
3 digit numbers for identification (see picture 1):
1 Bar: 039, 460, 883, 876
2 Bar: 886, 012, 539, 609, 701
3 Bar: 749, 861
The logic module uses the manifold absolute pressure (MAP) sensor to determine the absolute pressure (not the relative to atmospheric pressure) of the air inside the intake manifold and the atmosphere (barometric pressure).
This information is used to determine the density of the air entering the combustion chamber (in conjunction with the IAT(Intake Air temperature) sensor), which is used when calculating the proper air/fuel mixture for the engine, especially at WOT since the system is not in closed-loop at this time.
It is also used to help adjust the IAC(Idle Air Control) motor during idle.
It uses a silicon wafer that is thinner in the centre (0.001") than around the edges (0.045"), which causes it to act as a diaphragm.
It is mounted with a perfect vacuum beneath the chip so that the air pressure from the other side flexes the chip.
This flexing causes a change in resistance and the circuitry inside the sensor converts this to a voltage ranging from 0.02V to 4.94V when the output is pulled up towards 5V by the ECM(Electronic control module).
1 Bar MAP sensors are used on NA(naturally aspirated) vehicles.
2 Bar MAP Sensors are used on forced induction vehicles (Turbo & Supercharged). They can measure up to 2x the atmospheric pressure (29.4psi), so that means it can measure up to 14.7psi boost (the atmosphere is 14.7psi + 14.7psi from the turbo/supercharger).
3 Bar MAP sensors can measure up to 44.1psi, which translates to 29.7psi boost from a Turbo/supercharger.
They all share a common pin out, although the connector keying may be different:
Pin A -- Ground
Pin B -- Sensor output
Pin C -- +5 volts
Places to order MAP Sensors
You can order them direct from:
www.SummitRacing.com
PN# MSD-2313 3bar MAP
PN# MSD-2312 2bar MAP
PN# MSD-2311 1bar MAP
or
www.GMPartsDirect.com
PN# 12223861 3bar MAP
PN# 16040609 2bar MAP
PN# 16137039 1bar MAP
The chart below describes the pressure-to-voltage relationship of the stock GM Turbo MAP sensor (2 bar):
Manifold Pressure (relative sea level / absolute) 2 Bar MAP Output
14.31psi / 29.01psi 4.90V
14.00psi / 28.70psi 4.84V
13.00psi / 27.70psi 4.67V
12.00psi / 26.70psi 4.50V
11.00psi / 25.70psi 4.33V
10.00psi / 24.70psi 4.16V
9.00psi / 23.70psi 3.99V
8.00psi / 22.70psi 3.82V
6.00psi / 20.70psi 3.47V
4.00psi / 18.70psi 3.13V
2.00psi / 16.70psi 2.79V
0.00psi / 14.70psi 2.45V
5.00inHg / 12.24psi 2.03V
10.00inHg / 9.78psi 1.61V
15.00inHg / 7.33psi 1.19V
20.00inHg / 4.87psi 0.77V
25.00inHg / 2.41psi 0.35V
29.10inHg / 0.40psi 0.02V
MAP sensor output based on altitude (Ignition "ON" and engine stopped)
Altitude Voltage Range
Meters Feet --------------
Below 305 Below 1000 3.8--5.5V
305--610 1000--2000 3.6--5.3V
610--914 2000-3000 3.5--5.1V
914--1219 3000--4000 3.3--5.0V
1219--1524 4000--5000 3.2--4.8V
1524--1829 5000--6000 3.0--4.6V
1829--2133 6000--7000 2.9--4.5V
2133--2438 7000--8000 2.8--4.3V
2438--2743 8000--9000 2.6--4.2V
2743--3048 9000-10000 2.5--4.0V
Low altitude = High Pressure = High Voltage
GM 1bar, 2bar, 3bar
1 PSI = 2.036" of Mercury (HG)
1" mercury = 0.4911541 PSI
3 digit numbers for identification (see picture 1):
1 Bar: 039, 460, 883, 876
2 Bar: 886, 012, 539, 609, 701
3 Bar: 749, 861
The logic module uses the manifold absolute pressure (MAP) sensor to determine the absolute pressure (not the relative to atmospheric pressure) of the air inside the intake manifold and the atmosphere (barometric pressure).
This information is used to determine the density of the air entering the combustion chamber (in conjunction with the IAT(Intake Air temperature) sensor), which is used when calculating the proper air/fuel mixture for the engine, especially at WOT since the system is not in closed-loop at this time.
It is also used to help adjust the IAC(Idle Air Control) motor during idle.
It uses a silicon wafer that is thinner in the centre (0.001") than around the edges (0.045"), which causes it to act as a diaphragm.
It is mounted with a perfect vacuum beneath the chip so that the air pressure from the other side flexes the chip.
This flexing causes a change in resistance and the circuitry inside the sensor converts this to a voltage ranging from 0.02V to 4.94V when the output is pulled up towards 5V by the ECM(Electronic control module).
1 Bar MAP sensors are used on NA(naturally aspirated) vehicles.
2 Bar MAP Sensors are used on forced induction vehicles (Turbo & Supercharged). They can measure up to 2x the atmospheric pressure (29.4psi), so that means it can measure up to 14.7psi boost (the atmosphere is 14.7psi + 14.7psi from the turbo/supercharger).
3 Bar MAP sensors can measure up to 44.1psi, which translates to 29.7psi boost from a Turbo/supercharger.
They all share a common pin out, although the connector keying may be different:
Pin A -- Ground
Pin B -- Sensor output
Pin C -- +5 volts
Places to order MAP Sensors
You can order them direct from:
www.SummitRacing.com
PN# MSD-2313 3bar MAP
PN# MSD-2312 2bar MAP
PN# MSD-2311 1bar MAP
or
www.GMPartsDirect.com
PN# 12223861 3bar MAP
PN# 16040609 2bar MAP
PN# 16137039 1bar MAP
The chart below describes the pressure-to-voltage relationship of the stock GM Turbo MAP sensor (2 bar):
Manifold Pressure (relative sea level / absolute) 2 Bar MAP Output
14.31psi / 29.01psi 4.90V
14.00psi / 28.70psi 4.84V
13.00psi / 27.70psi 4.67V
12.00psi / 26.70psi 4.50V
11.00psi / 25.70psi 4.33V
10.00psi / 24.70psi 4.16V
9.00psi / 23.70psi 3.99V
8.00psi / 22.70psi 3.82V
6.00psi / 20.70psi 3.47V
4.00psi / 18.70psi 3.13V
2.00psi / 16.70psi 2.79V
0.00psi / 14.70psi 2.45V
5.00inHg / 12.24psi 2.03V
10.00inHg / 9.78psi 1.61V
15.00inHg / 7.33psi 1.19V
20.00inHg / 4.87psi 0.77V
25.00inHg / 2.41psi 0.35V
29.10inHg / 0.40psi 0.02V
MAP sensor output based on altitude (Ignition "ON" and engine stopped)
Altitude Voltage Range
Meters Feet --------------
Below 305 Below 1000 3.8--5.5V
305--610 1000--2000 3.6--5.3V
610--914 2000-3000 3.5--5.1V
914--1219 3000--4000 3.3--5.0V
1219--1524 4000--5000 3.2--4.8V
1524--1829 5000--6000 3.0--4.6V
1829--2133 6000--7000 2.9--4.5V
2133--2438 7000--8000 2.8--4.3V
2438--2743 8000--9000 2.6--4.2V
2743--3048 9000-10000 2.5--4.0V
Low altitude = High Pressure = High Voltage
GM 1bar, 2bar, 3bar
1 PSI = 2.036" of Mercury (HG)
1" mercury = 0.4911541 PSI
