Electronic Engine Controls

Electronic Engine Controls

The electronic engine controls consist of the following:

- PCM

- Camshaft Position (CMP) sensor

- Crankshaft Position (CKP) sensor

- Mass Air Flow (MAF) sensor

- Heated Oxygen Sensor (HO2S)

- Catalyst Monitor Sensor (CMS)

- Cylinder Head Temperature (CHT) sensor

- Knock Sensor (KS)

- Variable Camshaft Timing (VCT) oil control solenoid

- Manifold Absolute Pressure (MAP) 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 CMP (Camshaft Position) sensor:

- provides camshaft position information which is used by the PCM for fuel synchronization. Refer to Computers and Control Systems.

The CKP (Crankshaft Position) sensor:

- sends the PCM a signal indicating crankshaft position.

- is essential for calculating spark timing.

The MAF (Mass Air Flow) 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 HO2S (Heated Oxygen 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 CMS (Catalyst Monitor Sensor) :

- monitors oxygen content after it flows through the catalytic converter.

- provides feedback information to the PCM used to calculate fuel delivery.

The CHT (Cylinder Head Temperature) sensor:

- sends the PCM a signal indicating cylinder head temperature.

- resistance decreases as coolant temperature increases. Refer to Computers and Control Systems.

The KS (Knock Sensor) :

- 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.

The VCT (Variable Camshaft Timing) oil control solenoid:

- is an electrically controlled hydraulic valve that directs engine oil to the variable camshaft. Once the PCM transmits a signal, the solenoid moves a valve spool, directing oil into the camshaft phaser cavity. This action changes valve timing by either inducing an advance or retard condition. The camshaft is, thereby repositioned in relation to crankshaft timing and allows for optimum engine performance and lower emissions.

The MAP (Manifold Absolute Pressure) sensor:

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