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.
• Crankshaft position (CKP) sensor.
• Mass air flow (MAF) sensor.
• Manifold absolute pressure (MAP) sensor (2.3L).
• Intake air temperature (IAT) sensor.
• Heated oxygen sensor (HO2S).
• Catalyst monitor sensor.
• Wheel speed sensor.

The PCM:

• accepts input from various engine sensors to compute the fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operating range.
• outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

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:

• 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 the PCM a signal 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 MAP sensor:

• measures manifold vacuum and converts it to an electrical signal. This provides the PCM information on engine load.

The HO2S:

• 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 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 wheel speed sensor:

• sends a signal to the PCM indicating wheel speed.