Fuel Charging and Controls

Fuel Charging and Controls


Sequential Multi-Port Fuel Injection (SFI)

WARNING: Do not smoke, carry lighted tobacco or have an open flame of any type when working on or near any fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

The fuel charging and controls system consists of the following:

- Fuel injectors
- Fuel rail and fuel pressure relief valve
- Throttle Body (TB)

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.

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.


Fuel Injectors

The 8 fuel injectors:

- are electronically operated by the PCM.
- atomize the fuel as the fuel is delivered.
- each have an internal solenoid that opens a needle valve, which injects fuel into the intake port in the cylinder head.
- are deposit resistant.

For removal and installation, refer to Fuel Rail and Fuel Injector - Exploded View Fuel Rail and Fuel Injector - Exploded View and Fuel Rail Fuel Rail.


Fuel Pressure Relief Valve

The fuel pressure relief valve is located on the fuel rail and is used to relieve fuel pressure from the fuel system and for diagnostic testing.


Fuel Pump (FP) Control Module

The Fuel Pump (FP) control module:

- receives signals from the PCM.
- controls the duty cycle of the FP.


Fuel Rail

NOTICE: The fuel injectors and the fuel rail must be handled with extreme care to prevent damage to sealing areas and sensitive fuel-metering orifices.

The fuel rail:

- receives fuel from the fuel supply tube.
- delivers fuel to the fuel injectors.

For removal and installation, refer to Fuel Rail and Fuel Injector - Exploded View Fuel Rail and Fuel Injector - Exploded View and Fuel Rail Fuel Rail.


Throttle Body (TB)

The TB:

- controls air supply to the intake manifold by electronically positioning the throttle plate.
- is not adjustable.

Refer to Throttle Body Service and Repair.