This sensor is a semiconductor type sensor. It measures pressure utilizing the piezoelectric effect that when the pressure on the silicon element in the sensor changes, its electrical resistance changes. In addition, the air pressure on this sensor is switched between the pressure within the intake manifold and the atmospheric pressure, so both the intake air pressure and the atmospheric pressure are detected with one sensor. The switching between intake air pressure and atmospheric pressure is handled by the VSV (vacuum switching valve). When any one of the conditions below is established, the VSV is switched ON for 150 msec. by command of the engine ECU to detect the atmospheric pressure. When none of the conditions below is established, the VSV is switched OFF to detect the intake air pressure.
Atmospheric Pressure Measurement Conditions
– Engine speed = 0 rpm
– Starter ON
– Stable idling state
