Medallion L4-2165cc 2.2L (1988)
Manifold Pressure/Vacuum Sensor: Description and Operation
This sensor reacts to absolute pressure in the intake manifold by providing a voltage signal to the ECU. This signal is then used to calculate the
amount of fuel that enters the engine through the injectors.
The sensor is connected to the intake manifold by a tube and receives a 5 volt reference signal by the ECU. Changes in intake manifold pressure as a
result of different throttle openings alter the resistance of areas inside the sensor. Due to this resistance, the voltage signal sent back to the ECU will be
less than 5 volts. By measuring the difference between the reference voltage sent and the signal voltage received, the ECU is able to determine the
absolute pressure inside the intake manifold. As pressure in the intake manifold changes, the ECU determines the amount of change by measuring the
voltage drop across the sensor.
