Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the:
- powertrain control module (PCM).
- camshaft position (CMP) sensor.
- crankshaft position (CKP) sensor.
- throttle position (TP) sensor.
- mass air flow (MAF) sensor.
- heated oxygen sensor (HO2S).
- catalyst monitor sensor (CMS).
- charge motion control valve (CMCV) (5.4L).
- intake manifold runner control (IMRC) actuator (6.8L).
- knock sensor (KS).
- cylinder head temperature (CHT) sensor.
- engine oil temperature (EOT) sensor.
- variable camshaft timing (VCT) oil control solenoid (5.4L).
- clutch pedal position (CPP) switch.
- fuel rail pressure and temperature sensor.

The PCM needs the following inputs to control the engine correctly:
- Camshaft position
- Crankshaft position
- Engine rpm
- Engine cylinder head temperature
- Amount of engine detonation
- Fuel rail pressure and temperature

The CMP sensor:
- sends the PCM a signal indicating camshaft position used for fuel synchronization and coil firing.

The CKP sensor:
- sends the PCM a signal indicating crankshaft position.
- is essential for calculating spark timing.

The TP sensor:
- sends the PCM a signal indicating the throttle plate angle.
- is the main input to the PCM from the driver.

The MAF sensor:
- sends the PCM a signal indicating mass airflow rate of air entering the engine.
- incorporates the intake air temperature (IAT) sensor.

The HO2S and CMS:
- have the ability to create a voltage signal dependent on exhaust oxygen content.
- provide feedback information to the PCM used to calculate fuel delivery.

The KS sensor:
- is located top forward of the block under the intake manifold.
- sends a signal to the PCM indicating engine detonation.

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 126°C (258°F), the PCM disables 4 fuel injectors at a time. The PCM will alternate which 4 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 154°C (310°F), the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F).

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

The VCT oil control solenoid (5.4L):
- 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 CPP switch (manual transmission only):
- sends a signal to the PCM indicating clutch pedal position.

The 5.4L air induction system improves engine performance by using the CMCV assemblies as follows:
- The intake manifold has 2 runners per cylinder, feeding each of the intake ports in the cylinder heads.
- The CMCV assemblies are located between the intake manifold and cylinder heads, providing 2 air passages for each cylinder.
- One air passage is always open and the other passage switches from closed to open by means of a valve plate.
- The valve plates are opened and closed by the CMCV electric actuator, which is controlled by the PCM.

The 6.8L air induction system improves engine performance by using the IMRC as follows:
- The intake manifold has 2 runners per cylinder, feeding each of the intake ports in the cylinder heads.
- The IMRC assemblies are located between the upper intake manifold and cylinder heads, providing 2 air passages for each cylinder.
- The valve plates are opened and closed by the IMRC electric actuator, which is controlled by PCM.
- One air passage is always open and the other passage switches from closed to open by means of a valve plate.
- Below 1,500 rpm, this valve plate is closed to improve fuel economy and emissions.
- Above 1,500 rpm, this valve plate opens to improve high speed engine performance.