Electronic Engine Controls

Electronic Engine Controls

The electronic engine controls consist of the:

- PCM

- Cylinder Head Temperature (CHT) sensor

- 4 Camshaft Position (CMP) sensors, 1 for each camshaft

- Crankshaft Position (CKP) sensor

- Mass Air Flow (MAF) sensor

- Heated Oxygen Sensor (HO2S)

- Catalyst Monitor Sensor (CMS)

- 4 Variable Camshaft Timing (VCT) oil control solenoids, 1 for each camshaft

- 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 CHT (Cylinder Head Temperature) sensor:

- sends the PCM a signal indicating cylinder head temperature.

- decreases resistance as cylinder head temperature increases.

The CMP (Camshaft Position) sensor sends the PCM a signal indicating camshaft position used for fuel synchronization.

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. Air passing over the hot wire causes it to cool.

The HO2S (Heated Oxygen Sensor) :

- creates 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 voltage to the PCM to calculate catalytic converter integrity.

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 KS (Knock Sensor) :

- detects engine detonation.

- sends a voltage signal to the PCM.

- provides a signal which retards the ignition timing, as necessary.