Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the:
- power control module (PCM).
- engine coolant temperature (ECT) sensor.
- camshaft position (CMP) sensor.
- fuel rail pressure and temperature sensor.
- crankshaft position (CKP) sensor.
- mass air flow (MAF) sensor.
- heated oxygen sensor (HO2S).
- catalyst monitor sensor.
- knock sensor (KS).

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 operational range.
- outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

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 fuel rail pressure and temperature sensor:
- measures the pressure and temperature of the fuel in the fuel supply manifold and sends these signals to the PCM.
- uses intake manifold vacuum as a pressure reference.

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

The catalyst monitor sensor:
- 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 (spark knock).
- sends a voltage signal to the PCM which retards the ignition timing as necessary.