Electronic Engine Controls (EEC)
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 Airflow (MAF) sensor
Intake Air Temperature (IAT) sensor
Heated Oxygen Sensor (HO2S) - front
Heated Oxygen Sensor (HO2S) - rear
Cylinder Head Temperature (CHT) sensor
Powertrain Control Module (PCM):
-accepts input from various engine sensors to complete to complete the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire operational range.
-outputs a command to the fuel injectors to meter the appropriate quantity of fuel.
-determines and compensates for the age of the vehicle and its uniqueness, also automatically senses and compensates for changes in altitude.
Throttle Position (TP) sensor:
-sends the PCM a signal indicating the throttle plate angle.
is the main input to the PCM from the driver.
Idle Air Control (IAC) valve:
-controls bypass air around the throttle plate at low speeds.
is controlled by the PCM.
Camshaft Position (CMP) sensor:
-sends the PCM a signal indicating camshaft position.
is used for fuel synchronization.
Crankshaft Position (CKP) sensor:
-sends the PCM a signal indicating crankshaft position.
is essential for calculating spark timing.
-sends the PCM signals to indicate engine rpm.
Mass Airflow (MAF) sensor:
-sends the PCM a signal indicating fresh air flow rate of air entering the engine.
Intake Air Temperature (IAT) sensor:
-sends the PCM a signal indicating the temperature of the air entering the engine.
-resistance decreases as temperature increases.
Heated Oxygen sensor (H02S):
-has the ability to create a voltage signal dependant on exhaust oxygen content.
-provides feedback information to the PCM used to calculate fuel delivery.
rear H02S:
-monitors oxygen content after it flows through the catalytic converters.
-provides a voltage to the PCM used to calculate catalytic converter integrity.
Cylinder Head Temperature (CHT) sensor:
-is mounted to the wall of the cylinder head and is not connected to any coolant passages.
-sends a signal to the PCM indicating cylinder head temperature.
- if the temperature exceeds 250°F (121°C) the PCM disables four fuel injectors at a time. The PCM will alternate which injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine.
- if the temperature exceeds 330°F (166°C) the PCM disables all of the fuel injectors until the engine temperature drops below 310°F (154°C).
