MASS AIRFLOW SENSOR Mass airflow sensor is installed in the air intake hose. Mass airflow sensor is composed of an extremely small heatsensing resistor. The mass airflow sensor controls the amount of electric current flowing into the heat sensing resistor to keep the heat sensing resistor at a constant temperature to the intake air temperature. The faster the air flow speed, the higher the mass flow rate.Because the amount of heat transfer from the heat sensing resistor to the air increases, the mass airflow sensor increases the amount of electric current to the heat sensing resistor. Thus, the amount of electric current increases in accordance with the air mass flow rate. The mass airflow sensor measures the air mass flow rate by detecting the amount of electric current. The mass airflow sensor amplifies the detected electric current amount and outputs it into the ECM. ECM uses this output current and engine speed to calculate and decide basic fuel injection time. Sensor properties are as shown in the figure.
MANIFOLD ABSOLUTE PRESSURE SENSOR The manifold absolute pressure sensor is installed in the intake manifold. Manifold absolute pressure sensor uses a piezo resistive semiconductor to output the voltage according to manifold absolute pressure to ECM. ECM uses this output voltage to compensate fuel injection volume according to manifold absolute pressure. Sensor properties are as shown in the figure.