Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the following:
- PCM
- Throttle position (TP) sensor
- Camshaft position (CMP) sensor
- Crankshaft position (CKP) sensor
- Mass air flow (MAF) sensor
- Heated oxygen sensor (HO2S) - front
- Catalyst monitor sensor - rear
- Knock sensor (KS)
- Cylinder head temperature (CHT) sensor
- Fuel rail pressure and temperature sensor
- Output shaft speed (OSS) sensor

The PCM needs the following inputs to calibrate the engine correctly:
- Air temperature
- Throttle position
- Crankshaft position
- Camshaft position
- Engine rpm
- Cylinder head temperature
- Amount of engine detonation
- Engine coolant temperature
- Mass airflow

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

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

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

The MAF sensor:
- sends the PCM a signal indicating the temperature of the air entering the engine.
- sends the PCM a signal indicating mass air flow rate of air entering the engine.

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 catalyst monitor oxygen sensors:
- monitor oxygen content after the catalytic converter.
- provide a voltage to the PCM used to calculate catalytic converter integrity.

The KS:
- is located in the intake valley.
- sends a signal to the PCM indicating engine detonation.

The CHT sensor:
- is mounted into the front of the left 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 some fuel injectors. The PCM will alternate which fuel injectors are disabled every 24 engine cycles. The 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 124°C (255°F).

The OSS sensor:
- is gear driven by the transmission.
- sends a signal to the PCM indicating transmission output shaft speed. Refer to Transmission Control Systems.