Fuel Delivery and Air Induction: Description and Operation

FUEL DELIVERY
The Sequential Multiport Fuel Injection (SFI) provides the fuel/air mixture needed. The induction system is mounted on an aluminum intake manifold. Fuel flow is as follows:
1. Fuel is supplied from the vehicle fuel tank by a high-pressure electric fuel pump mounted in the fuel tank.
2. The fuel is then filtered and sent to the fuel injection supply manifold.
3. A fuel pressure regulator on the fuel injection supply manifold controls the fuel delivery pressure at a constant 269 kPa (39 psi).
4. Excess fuel supplied by the fuel pump, but not needed by the engine, is returned to the fuel tank by a fuel return line.

Fuel Injectors
The six fuel injectors are:
- Positioned so that their tips direct fuel just ahead of the engine intake valves.
- Connected in parallel with the fuel pressure regulator.

Fuel Injection Timing
For fuel injection timing:
- each fuel injector is energized once every other crankshaft revolution in sequence with firing order.
- the period of time that the fuel injectors are energized (fuel injector on time or pulse width) is controlled by the vehicle's Powertrain Control Module (PCM).
- air entering the engine is monitored by flow and temperature sensors.
- the outgoing signals of the electronic engine control sensors are processed by the PCM.
- the PCM determines the needed fuel injector pulse width and sends a command to the fuel injectors to meter the exact quantity of fuel.

AIR INDUCTION
Components
All engines are equipped with:
- Replaceable dry-type Air Cleaner Element (ACL).
- Engine air tray, attached to the RH front fender apron.
- Mass Air Flow (MAF) sensor.

Operation
The air induction system supplies clean air to the throttle body. It operates as follows:
- Outside air enters from an air intake in the engine air tray through an opening in the front fender apron.
- In the engine air tray, air is filtered by the air cleaner element.
- From the engine air tray, the filtered air travels through the mass air flow sensor and air cleaner outlet tube to the throttle body.
- The Positive Crankcase Ventilation (PCV) system is also supplied clean air through a fitting on the air cleaner outlet tube.
- Air induction noise is effectively tuned by means of the sealed cover with integral resonator, which is part of the mass air flow sensor.