Electronic Engine Controls

The electronic engine controls consist of the following:
^ Power Control Module (PCM)
^ Throttle Position (TP) sensor
^ Idle Air Control (IAC) valve
^ Engine Coolant Temperature (ECT) sensor
^ Camshaft Position (CMP) sensor
^ Crankshaft Position (CKP) sensor
^ Mass Air Flow (MAF) sensor
^ Intake Air Temperature (IAT) sensor
^ Heated Oxygen Sensor (HO2S)
^ catalyst monitor sensor
^ Output Shaft Speed (OSS) sensor

The PCM:
^ accepts input from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range.
^ outputs a command to the fuel injectors to meter the appropriate quantity of fuel.
^ determines and compensates for the age of the vehicle and its uniqueness, also automatically senses and compensates in altitude (i.e. from sea level to above sea level).

The TP sensor:
^ sends the PCM a signal indicating the throttle plate angle.
^ is the main input to the PCM from the driver.

The IAC valve:
^ is used to control engine idle speed.
^ is controlled by the PCM.

The ECT sensor:
^ sends the PCM a signal indicating engine temperature.
^ resistance decreases as coolant temperature increases.

The CMP sensor:
^ provides camshaft position information which is used by the PCM for fuel synchronization.

The CKP sensor:
^ sends the PCM a signal indicating crankshaft position.
^ is essential for calculating spark timing.

The MAF sensor:
^ uses a hot wire sensing element to measure the amount of air entering the engine.
^ sends a signal to the PCM to determine the intake air mass. The PCM will then calculate the required fuel injector pulse width in order to provide the desired air/fuel ratio.

The catalyst monitor sensor:
^ has the ability to create a voltage signal dependent on exhaust oxygen content.
^ provides feedback information to the PCM used to calculate fuel delivery.

The HO2S:
^ monitors oxygen content after it flows through the catalytic converter.
^ provides a voltage to the PCM used to calculate catalytic converter integrity.

The PSP switch:
^ is a normally closed switch that opens as pressure increases.
^ is used to send a signal to the PCM to adjust idle speed. This compensates for the additional load on the engine.

The OSS:
^ is able to provide a signal which tells the PCM the vehicle speed.