Fuel Delivery and Air Induction: Description and Operation

Engine View:

The Electronic Fuel Injection system (EFI) is classified as a multi-point time pulse fuel injection system. Fuel is metered into the intake air stream through six injectors mounted in the lower manifold near the intake ports.

An on-board digital Electronic Engine Control (EEC-IV) microcomputer receives inputs from various engine sensors and uses this information to compute the required fuel flow rate necessary to compute the prescribed air/fuel ratio for a given engine operation. This allows the air/fuel ratio to be very accurately controlled. The EEC-IV computer is programmed to automatically compensate for vehicle age or variability and change in altitude and also to permit push-starting the vehicle should it become necessary (manual transmission only).
The fuel delivery subsystem consists of a high-pressure, in-tank mounted fuel pump, delivering fuel from the fuel tank through a 20-micron fuel filter to a fuel charging manifold assembly.
The lower intake manifold assembly contains the solenoid actuated fuel injectors. The injectors (when energized) spray fuel into the intake stream near the intake valve.
Constant fuel pressure is maintained at the injector nozzles by a pressure regulator. Fuel supplied by the high-pressure pump, but not required by the engine, bypassed through the regulator and returns to the fuel tank.
The period of time the injectors are energized (injector "on time" or pulse width) is controlled by the vehicle computer. The pulse width is calculated by input data received from the Exhaust Gas Oxygen (EGO) sensor, Manifold Absolute Pressure sensor (MAP), Engine Coolant Temperature (ECT), engine rpm (PIP), Air Charge Temperature (ACT) and time since-start.