Charge air absolute pressure sensor: Notes
There are two metal coated ceramic discs mounted close to each other in the pressure sensor. The disc closest to the pressure connection is thinner and bends when exerted to pressure. This changes the capacity between the metal coatings on the discs in relation to the pressure. Integrated in the sensor is a circuit that converts the capacity to an analogue voltage. The pressure sensor, which is combined with the temperature sensor is located on the engine intake manifold before the throttle and is powered with 5V from control module pin 46 and grounded from control module pin 70.
Depending on the pressure in the charge air pipe, the pressure sensor delivers a proportional voltage to control module pin 35.
The air mass control determines which air mass/combustion is to be drawn in during the cylinder's induction stroke. The value corresponds to the engine torque.
Throttle control adjusts the throttle so that the current air mass/combustion is the same as the requested.
If the air in front of the throttle has a high density, a smaller throttle angle will be required than if the air density is low. The density of the air is therefore calculated by the control module using the charge air pressure and the intake air temperature.
At normal atmospheric pressure, 100 kPa, the pressure from the sensor is approx. 2.1 V.