Sequential Multi-Port Fuel Injection (SFI)

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

The fuel charging and controls system consists of the:

Throttle Body (TB).
fuel injectors.
fuel rail.
Fuel Pump (FP) control module.

The fuel charging and controls system is:

a Sequential Multi-Port Fuel Injection (SFI) system.
Pulse Width Modulated (PWM).
Mass Air Flow (MAF) controlled.

Fuel is metered into each intake port in a sequential firing order. Fuel injectors pulse to follow engine firing order in accordance with engine demand on a tuned intake manifold.

The basic fuel requirement of the engine is determined from the data supplied to the PCM by the MAF sensor, which measures the amount of air being drawn into the engine.

Other sensors are used to measure:

air temperature.
engine coolant temperature.
engine speed.
exhaust oxygen content.

The various sensors detect any changes in the operating conditions and send signals to the PCM. This permits the PCM to control the opening duration (pulse width) of the fuel injectors and maintain optimum exhaust emission control and engine performance for all operating conditions.