Injection System

INJECTION SYSTEM

Injection is performed by the fuel injection valves, which spray finely atomized fuel to the intake valves. These are actuated sequentially by the PCM, in other words, one injection valve is assigned to each cylinder and meters the quantity of fuel which is calculated for the cylinder. The main measured variable for determining the fuel volume is the air mass supplied to the engine, which is detected by the hot film mass air flow (MAF) sensor.

The PCM can adapt its fuel injection strategy to meet changing operating conditions.

Fuel is injected into the intake port above the intake valve in precise metered amounts through electrically operated injectors. The PCM fires the injectors in a specific sequence. Under most operating conditions, the PCM maintains an air fuel ratio of 14.7 parts air to 1 part fuel by constantly adjusting injector pulse width based on input received from the oxygen sensors. Injector pulse width is the length of time the injector is open and delivering fuel into the intake manifold port.

The PCM adjusts injector pulse width by opening and closing the ground path to the injector. Engine RPM (speed) and manifold absolute pressure (air density) are the primary inputs that determine injector pulse width.