Fuel Injector: Description and Operation

Injectors And Related Components:

Fuel Injector:

The fuel injectors, located on the intake manifold near the cylinder head, are electrically operated, high impedance solenoid valves that open when energized. The injectors get battery power from the main relay when the ignition is in the either the "START" or "RUN" position, and are energized when the ECU completes the circuit to ground. Injection timing and duration are determined by the engine control unit. Injectors are energized either all at the same time once each crankshaft revolution (during cranking and cold engine operation), or in pairs (normal warm engine operation).

Typical Fuel Injector:

The injectors are constructed of stainless steel and high density plastic, to resist corrosion. They consist of a fuel inlet with filter screen, an electrical solenoid and connector, and a pintle valve and nozzle. Injectors are held in place by the fuel rail and sealed by an O-ring and insulator.

To calculate fuel injection quantity and timing, the ECU utilizes information from various input sensors, making adjustments needed to maintain good driveability, fuel economy and low emissions under the full range of operating conditions.

Input information is calculated from these devices:

Distributor "Ne" signal
Distributor "G" signal
Water thermosensor
Oxygen sensor
Airflow meter
Intake air thermosensors
Throttle sensor/idle switch
Atmospheric pressure sensor
Inhibitor switch (A/T)
A/C switch