Electronic Engine Controls

The electronic engine controls consist of the following:
^ Powertrain Control Module (PCM)
^ Throttle Position (TP) sensor
^ Idle Air Control (IAC) valve
^ Engine Coolant Temperature (ECT) sensor
^ Camshaft Position (CMP) sensor
^ Camshaft Synchronizer
^ Crankshaft Position (CKP) sensor
^ Mass Air Flow (MAF) sensor
^ Intake Air Temperature (IAT) sensor
^ Heated Oxygen Sensor (HO2S)
^ Knock Sensor (KS)

The PCM performs the following functions:
^ 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 for changes in altitude.

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:
^ controls bypass air around the throttle plate at low speeds.
^ 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:
^ sends the PCM a signal indicating camshaft position used 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. Air passing over the hot wire causes it to cool.

The IAT sensor:
^ sends the PCM a signal indicating the temperature of the air entering the engine.
^ is repaired as an assembly with the MAF.

The front HO2S:
^ creates a voltage signal dependent on exhaust oxygen content.
^ provides feedback information to the PCM used to calculate fuel delivery.

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

The KS:
^ is used to detect engine detonation.
^ sends a voltage signal to the PCM.
^ is able to provide a signal which retards the ignition timing, as necessary.