Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the following:
^ Powertrain Control Module (PCM)
^ Throttle Position (TP) sensor
^ Idle Air Control (IAC) valve
^ Camshaft Position (CMP) sensor
^ Crankshaft Position (CKP) sensor
^ Mass Air Flow (MAF) sensor
^ Intake Air Temperature (IAT) sensor
^ Heated Oxygen Sensor (HO2S) - front
^ Heated Oxygen Sensor (HO2S) - rear
^ Knock Sensor (KS) Cylinder Head Temperature (CHT) sensor
^ Power Steering Pressure (PSP) switch
^ fuel pressure sensor
^ Vehicle Speed Sensor (VSS)

The powertrain control module needs the following inputs to calibrate the engine correctly:
^ camshaft position
^ engine rpm
^ cylinder head temperature
^ clutch pedal position
^ amount of engine detonation
^ mass air flow (MAF) sensor

The throttle position sensor:
^ sends the powertrain control module a signal indicating the throttle plate angle.
^ is the main input to the powertrain control module from the driver.

The idle air control valve:
^ supplies air to the fuel rail for better atomization of fuel
^ controls bypass air around the throttle plate at low speeds.
^ is controlled by the powertrain control module.

The camshaft position sensor:
^ sends the powertrain control module a signal indicating camshaft position used for fuel synchronization.

The power steering pressure switch:
^ is located on the power steering pump, generates a differential pressure, and is dependent on current input.
^ controls the spool valve in the power steering pump.
^ regulates the hydraulic flow and, when combined with a current controlling device, yields a variable assist power steering system.
^ is controlled by the PCM to increase power steering pump flow and power steering assist at low vehicle speeds and to reduce power steering pump flow and power steering assist at high vehicle speeds.
^ is controlled by the PCM to increase the power steering pump flow, thereby increasing power steering assist for evasive maneuvering at high vehicle speeds (steering wheel rotation rate greater than 22 rpm).

The crankshaft position sensor:
^ sends the powertrain control module a signal indicating crankshaft position.
^ is essential for calculating spark timing.

The mass air flow sensor:
^ sends the powertrain control module a signal indicating mass air flow rate of air entering the engine.

The intake air temperature sensor:
^ sends the powertrain control module a signal indicating the temperature of the air entering the engine.
^ resistance decreases as temperature increases.

The heated oxygen sensors:
^ monitor oxygen content before and after the exhaust flows through the catalytic converter.
^ provide a voltage to the powertrain control module used to calculate catalytic converter integrity.

The knock sensor:
^ is located in the intake valley.
^ sends a signal to the powertrain control module indicating engine detonation. (If detonation is occurring, the powertrain control module then changes spark timing.)

The cylinder head temperature sensor:
^ is mounted into the wall of the cylinder head and is not connected to any coolant passages.

The fuel pressure sensor:
^ sends the powertrain control module a signal indicating fuel pressure.
- The powertrain control module uses the fuel pressure sensor signal and the fuel temperature sensor signal to maintain the fuel liquid pressure in the fuel line which reduces the fuel vapor pressure in the fuel line.
^ sends a signal to the powertrain control module indicating the cylinder head temperature.
- If the temperature exceeds approximately 121°C (250°F), the powertrain control module disables half the fuel injectors at a time. The powertrain control module 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 cooling the engine.
- If the temperature exceeds approximately 166°C (330°F), the powertrain control module 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 DTCs are set.

The vehicle speed sensor:
^ sends a frequency signal to the powertrain control module.
- The powertrain control module uses the vehicle speed sensor signal to calculate vehicle speed and to determine shift scheduling and electronic pressure control.

The intake manifold tuning valve:
^ connects the plenums to improve upper rpm power.