Fuel Charging and Controls

FUEL CHARGING AND CONTROLS

Sequential Multiport Fuel Injection (SFI)

WARNING: Do not smoke or carry lighted tobacco or 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 personal injury.

The fuel charging and controls system consists of the:
- throttle body.
- fuel injectors.
- fuel rail.
- fuel rail pressure and temperature sensor.
- fuel pump driver module.

The fuel charging and controls system is:
- a sequential multiport 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 powertrain control module (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.

Throttle Body (TB)

CAUTION: Do not hold the throttle plate open with any object that could scratch the bore or plate while servicing or cleaning the throttle body. Refer to Throttle Body.

The TB:
- controls air supply to the intake manifold by electronically positioning the throttle plates.
- is not adjustable.
- must be removed from the vehicle to be cleaned.

Fuel Rail

CAUTION: 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.

Fuel Injectors
The fuel injectors:
- are electronically operated by the PCM.
- atomize the fuel as the fuel is delivered.
- each have an internal solenoid which opens a needle valve to inject fuel into the intake manifold.
- are deposit-resistant.

Fuel Rail Pressure and Temperature Sensor
The fuel rail pressure and temperature sensor:
- maintains constant fuel pressure to the fuel injectors and throughout the fuel system.
- is spring-loaded and operated by intake manifold vacuum.

Fuel Pump Driver Modules (FPDM)
The FPDM(S):
- each controls one fuel pump.
- receives signals from the PCM.
- duty cycles the fuel pumps.