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 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 basic fuel requirement of the engine is determined from the data supplied to the powertrain control module (PCM) by the mass air flow (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.

Electronic Throttle Body
The electronic throttle body:
- controls air supply to the intake manifold by electronically positioning the throttle plate.
- is not adjustable.
- must not be cleaned.
- is serviced as an complete assembly only.

Fuel Injectors
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.