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.
- mass air flow-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 powertrain control module (PCM) controls the fuel injection system. Injector pulse width is varied to control the amount of fuel flow. Varying fuel pump output controls fuel pressure. The PCM commands the fuel pump driver module, which directly controls the fuel pump. The throttle body is electronically controlled by the engine management system (EMS). Throttle plate angle is changed electronically in response to throttle pedal movements initiated by the driver.

Throttle Body

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.

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

Fuel Injectors
The 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.

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 Rail Pressure and Temperature Sensor
The fuel rail pressure and temperature sensor:
- measures the pressure and temperature of the fuel rail and sends these signals to the PCM.
- uses intake manifold vacuum as a pressure reference.

Fuel Pump Driver Module (FPDM)
The FPDM:
- receives signals from the PCM.
- duty cycles the fuel pump.