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 data 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). The regulator is downstream from the injectors.
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 eight solenoid-operated fuel injectors are:
- Are mounted in the fuel injection supply manifold and the Intake Manifold Runner Control (IMRC) assemblies above the cylinder heads (6049).
- Positioned so that their tips direct fuel just ahead of the engine intake valves.
- Connected in series 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 ignition firing order.
- The period of time that the fuel injectors are energized (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 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).
- Mass Air Flow (MAF) sensor.

Operation
The air induction system performs the following functions:
- Supplies clean air to the throttle body.
- Allows outside air to enter from an air cleaner outlet tube, through an opening in the inner fender to the engine air cleaner.
- Filters air through the air cleaner element.
- From the engine air cleaner, the filtered air travels through the mass air flow sensor, located inside of the engine air cleaner and air cleaner outlet tube and into the throttle body.
- Supplies clean air to the Positive Crankcase Ventilation (PCV) system through a fitting on the air cleaner outlet tube
- Effectively eliminates air induction noise by means of the sealed and tuned resonator chambers located in the air cleaner intake resonator.