Powertrain Management: Description and Operation

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the following:

- PCM
- Cylinder head temperature (CHT) sensor
- Electronic throttle control (ETC)
- Throttle position (TP) sensor
- Camshaft position (CMP) sensor
- Crankshaft position (CKP) sensor
- Mass air flow (MAF) sensor
- Heated oxygen sensor (HO2S)
- Catalyst monitor sensor
- Knock sensor (KS)
- Variable cam timing (VCT) solenoid
- Accelerator pedal position (APP) sensor
- Manifold absolute pressure (MAP) sensor

The PCM carries out the following functions:

- 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 sensor:

- sends the PCM a signal indicating cylinder head temperature.
- resistance decreases as coolant temperature increases.The APP sensor:

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

- controls the throttle plate at all engine speeds including idle.
- is controlled by the PCM.The TP sensor:

- sends the PCM a signal indicating the throttle plate angle.The CMP sensor:

- sends the PCM a signal indicating camshaft position used for fuel synchronization.The VCT solenoid:

- controls the phase angle of the camshaft advancing or retarding timing, the PCM calculates and determines the desired camshaft position.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 MAP sensor:

- the PCM uses information from the MAP sensor to measure how much exhaust gas is introduced into the intake manifold.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.
- sends a voltage signal to the PCM.
- is able to provide a signal which retards the ignition timing, as necessary.