Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the following:
- Powertrain control module (PCM)
- Throttle position (TP) sensor
- Two camshaft position (CMP) sensors
- Crankshaft position (CKP) sensor
- Mass air flow (MAF) sensor
- Heated oxygen sensors (HO2S)
- Catalyst monitor sensors
- Two knock sensors (KS)
- Cylinder head temperature (CHT) sensor
- Power steering pressure (PSP) switch
- Fuel pressure sensor
- Fuel temperature sensor

The PCM carries out the following functions:
- Accepts inputs from various engine sensors to compute the fuel flow rate necessary to maintain a prescribed air/fuel ratio and spark synchronization throughout the entire engine operating range.
- Outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

The TP sensors:
- send the PCM a signal indicating the throttle plate angle.
- are the main input to the PCM from the driver.

The CMP sensors:
- send the PCM a signal indicating camshaft position used for fuel and spark 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 mass airflow rate of air entering the engine.

The front HO2S:
- creates a voltage signal dependent on exhaust oxygen content.
- provides feedback information to the PCM used to calculate fuel delivery.

The catalyst monitor sensors:
- monitor oxygen content after it flows through the catalytic converter.
- provide a voltage signal 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 that retards the ignition timing, if necessary.

The cylinder head temperature 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 half the fuel injectors at a time. The PCM will alternate which fuel injectors are disabled every 32 engine cycles. The cylinders that are not being fuel injected act as air pumps to aid in engine cooling.
- 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).
- The coolant temperature gauge pointer will read fully hot.
- The check gauge warning indicator will illuminate and DTC's are set.

The PSP switch:
- monitors the outlet pressure of the power steering pump and is calibrated to both an actuation and release pressure setting.
- increases the outlet pressure to match the severity of the turn maneuver.

The fuel pressure sensor:
- sends the PCM a signal indicating fuel pressure.
- The PCM uses the fuel pressure sensor signal to maintain the fuel liquid pressure in the fuel line which reduces the fuel vapor pressure in the fuel line.

The fuel temperature sensor:
- sends the PCM a signal indicating fuel temperature.
- The PCM uses the fuel temperature sensor signal to help maintain a prescribed air/fuel ratio and spark synchronization throughout the entire engine operating range.