Intake air OBD2 Scanner Code pressure sensor

Overview of the intake air pressure sensor
EFI engine intake pressure sensor is OBD2 Scanner Code used to detect the intake air amount is called a D-type injection system (speed-density type). Intake air pressure sensor detects the intake air is not directly detected as the intake air flow sensor, instead of using indirect detection, but also influenced by many factors, and thus there are many different from the amount of the sensor into the airflow in the detection and repair , arising from the failure of its particularity.
Intake air pressure sensor works
Intake pressure detected by the sensor section, the the valve rear of the intake manifold absolute pressure, which in accordance with the engine speed and the magnitude of the load detected by the change of the absolute pressure in the manifold, and then converted into a signal voltage supplied to the electronic controller (ECU) , ECU according to the magnitude of the voltage of this signal, the control of the size of the basic fuel injection quantity.
More types of intake air pressure sensor, pressure-sensitive resistive and capacitive. As the pressure-sensitive resistive response time, high detection accuracy, small size and installation advantages of flexible, they have been widely used in the D-type injection system.
The varistor type intake pressure sensor works.
Strain resistor R1, R2, R3, R4, and they constitute a Wheatstone bridge and are bonded together with the silicon diaphragm. Silicon diaphragm in the manifold absolute pressure can be deformed, thereby causing a change in resistance of the strain resistance R, the higher the manifold absolute   MaxiScan OBD2 Scanner pressure, the greater the deformation of the silicon diaphragm, thereby the greater the change in resistance of the resistor R . That mechanical changes of the silicon diaphragm is transformed into an electrical signal, and then output to the ECU by IC amplified.
The output characteristics of the intake air pressure sensor
During engine operation, as the throttle opening degree of change, the degree of vacuum within the intake manifold absolute pressure, and the output signal characteristic curve changes. However, changes in the relationship between them is what? The output characteristic curve is positive or negative? This problem is often difficult to be understood, that some maintenance personnel in the work with a feeling of "not sure".