4. Fuel Injection System
4-9
Manifold Absolute Pressure (MAP) / Engine Water Temperature (TW) / Intake Air
Temperature (TA) Sensors
Engine water temperature / Intake air temperature sensor:
Use the variable resistor of negative temperature coefficient (thermistor) to sense the outside temperature.
The electrical resistance value goes down when the temperature rises. On the contrary, the electrical
resistance value becomes higher when the temperature falls. Sensors provide the temperature of the
engine coolant and intake air to ECU to determine the injection and ignition timing.
Manifold absolute pressure sensor:
Manifold absolute pressure sensor (MAP Sensor) uses the piezoresistive resistor composed of silicon
diaphragm, forming the Wheatstone bridge circuit to measure the atmospheric pressure and the intake
manifold pressure, which are both transmitted to ECU for reference of engine control.
TW Senso
T
Senso
ECU
Working voltage (5V)
Output voltage
5V
MAP Senso
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Inlet
pressure
Inlet pressure (kPa)
Output voltage
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