Barometric Pressure Sensor: Description and Operation

The pressure sensor, installed on the firewall, senses ambient barometric pressure and absolute pressure in the intake manifold. Ambient barometric pressure is sensed by the sensor energizing the solenoid valve by the ECU for a pre-set time period immediately after engine starting and thereafter once every time period. Ambient pressure information is sent to the ECU for controlling fuel delivery time. During times when barometric pressure is not being sensed, the solenoid valve is de-energized and the sensor detects intake manifold pressure. This information is sent to the ECU for controlling fuel delivery time and idle speed.