Electronic Engine Controls

Electronic Engine Controls

The electronic engine controls consist of the:

- Camshaft Position (CMP) sensor.
- Crankshaft Position (CKP) sensor.
- Cylinder Head Temperature (CHT) sensor.
- fuel rail pressure and temperature sensor.
- Heated Oxygen Sensor (HO2S).
- Catalyst Monitor Sensor (CMS).
- Mass Air Flow (MAF) sensor.
- PCM.
- Knock Sensor (KS).

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 CHT sensor:

- is mounted into the wall of the cylinder head and is not connected to any coolant passages.
- sends a signal to the PCM indicating the cylinder head temperature.
- If the temperature exceeds approximately 121°C (250°F), the PCM disables 4 fuel injectors at a time. The PCM will alternate which fuel injectors are disabled every 32 engine cycles. The 4 cylinders that are not being fuel injected act as air pumps to aid in cooling the engine.
- If the temperature exceeds approximately 166°C (330°F), the PCM disables all of the fuel injectors until the engine temperature drops below approximately 154°C (310°F).

- If the engine reaches critical temperature, the following happens:
- The coolant temperature gauge pointer will read fully hot at approximately 121°C (250°F).

The fuel rail pressure and temperature sensor:

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

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 CMS(s):

- has the ability to create a voltage signal dependent on exhaust oxygen content.
- provides a voltage to the PCM used to calculate catalytic converter integrity.

The MAF sensor:

- sends the PCM a signal indicating fresh air flow rate of air entering the engine.

The PCM carries out the following functions:

- accepts input from various engine sensors to complete the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire 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 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.