Manifold Absolute Pressure Sensor (MAPS) & Intake Air Temperature Sensor (IATS)
In order to determine the fuel injection volume, the exact amount of air flow to the engine must be measured. The Manifold Absolute Pressure Sensor (MAPS) indirectly calculates the amount of air by measuring the pressure inside the intake manifold.
This mechanism is called Speed-Density Type.
The MAPS transmits to the engine Electronic Control Unit (ECU) analog output signals that fluctuate proportionally to the change of intake manifold pressure. With these signals and RPM, the engine ECU calculates the amount of intake air flow. The MAPS has a built-in intake temperature sensor (Intake Air Temperature Sensor (IATS)) and is mounted on the surge tank to measure the pressure of the intake manifold. It consists of a piezoelectric element and hybrid IC which amplifies output signals from the element. The piezoelectric element is a silicone diaphragm that incorporates piezoelectric effect. One side of the diaphragm is a vacuum chamber, while the other side is controlled by intake pressure. That is, if the intake pressure changes, the silicone diaphragm generates signals by flapping.