Multi-Port Fuel Injection (SFI)

Multi-Port Fuel Injection (SFI):

The purpose of the fuel control system is to deliver the correct amount of fuel to the engine under all operating conditions. Fuel is delivered to the engine by individual fuel injectors mounted in the ports of the intake manifold.

The ECM controls the amount of fuel delivered by changing how long fuel injectors arc turned On and Off. Injectors are turned on individually and sequentially before intake valve opening Sequential Fuel Injection (SFI).

During closed loop operation, the main control sensor is the oxygen sensor, which is located in the exhaust manifold. This sensor indicates to the ECM how much oxygen is in the exhaust gas, and the ECM changes the fuel to the engine based on this information by controlling how long the fuel injectors are pulsed. The best mixture to minimize exhaust emissions is 14.7:1 air/fuel ratio, which allows the three way catalytic converter to operate most efficiently. Because of the constant measuring and adjusting of the air/fuel ratio, the fuel injection system is called a Closed Loop system.

Fuel injector pulses are synchronized with the ignition reference (2X) pulse to the ECM.