Intake Air Distribution and Filtering

Intake Air Distribution and Filtering

COMPONENT LOCATION









INTRODUCTION
The intake air distribution and cleaning system comprises:
- Dual air intakes, air cleaners and air ducts.
- An intake manifold.
- A noise feedback system.

AIR INTAKES, AIR CLEANERS AND AIR DUCTS









The air intakes supply air from behind the front bumper to the air cleaners. A grommet and bracket attaches each air intake to the related side air deflector of the radiator. The RH (right-hand) air intake incorporates a bracket for the pollution sensor.
The air cleaners are located forward of the front wheels, behind the fender splash shields. Two mounting points, both consisting of a grommet installed on a bracket, attach each of the air cleaners to the fender extension of the related front side member and to a bracket on the front bumper beam. Each air cleaner consists of a casing with inlet and outlet connections. A removable cassette drawer holds a tray and a replaceable air cleaner element in the casing. Two screws secure the cassette drawer in the closed position in the casing. The underside of the casing incorporates a drain valve to prevent the accumulation of water in the air cleaner. The outlet connection of each air cleaner incorporates a MAFT (mass air flow and temperature) sensor.

Air Cleaner









The air ducts direct the air from the air cleaners to the electric throttle. The air ducts consist of LH (left-hand) and RH (right-hand) outlet ducts, LH (left-hand) and RH (right-hand) engine intake ducts and a throttle T-piece duct. Hose clamps connect the ducts together and to the air cleaners and the electric throttle.
The air ducts incorporate the following mounting points, which all consist of a grommet installed on a bracket:
- One on each outlet duct, attached to the related front side member.
- One on each engine intake duct, attached to brackets on the front cross member.
- One on the throttle T-piece duct, attached to a bracket on the RH (right-hand) cylinder head.
The air ducts also incorporate the following:
- On the outlet ducts, quarter wave tubes and Helmholtz resonators to reduce air induction noise.
- On the LH (left-hand) engine intake duct, a connector stub for the engine full load breather pipe.
- On the throttle T-piece, a connector stub for the noise feedback tube.


INTAKE MANIFOLD









The intake manifold is installed between the cylinder heads and directs air from the electric throttle to the individual cylinders. The inlet port connects to a central chamber in the intake manifold. Eight separate tracts connect the central chamber to the outlet ports. A cover plate seals the rear of the intake manifold.
The intake manifold incorporates:
- A stub pipe for connection of the part load breather.
- A stub pipe for connection of the evaporative emissions system.
- A MAP (manifold absolute pressure) sensor.
- A vacuum connection for the brake booster.
- Threaded inserts to provide attachment points for the electric throttle, fuel crossover tube, engine cover and an engine harness shield.
- Compression limiters in the cylinder head attachment points.
- Seals in the inlet and outlet ports.
- A VIS (variable intake system).

Variable Intake System









The VIS changes the length of the tracts in the intake manifold to improve the air flow to the cylinders, which improves the engine power and torque.
A cassette in the intake manifold contains eight flap valves, each located in an opening part-way along one of the tracts. Two drive shafts connect the flap valves together in two groups of four. Each drive shaft is connected to a pneumatic actuator installed on the cover plate of the intake manifold.
A tuning valve, also installed on the cover plate, controls the application of vacuum pressure to the pneumatic actuators. The tuning valve is a normally-closed solenoid-operated valve installed in the vacuum line between the cover plate and the pneumatic actuators. A vent cap on the tuning valve allows atmospheric pressure into the vacuum line to the pneumatic actuators when the tuning valve is closed.
The ECM (engine control module) controls the operation of the tuning valve.

NOISE FEEDBACK SYSTEM









The noise feedback system generates a sporty, powerful engine sound in the passenger compartment to enhance the driving experience. The noise feedback system consists of a feedback tube and a resonator.
The feedback tube transfers induction sound waves into the resonator. Clips secure the feedback tube to the resonator and to the throttle T-piece air duct.
The resonator modifies sound waves of a specific frequency range to produce the required engine tone and sound volume. The resonator is installed in the passenger compartment side of the engine bulkhead, mounted on two grommet assemblies consisting of an isolator and a compression limiter.

CONTROL DIAGRAM (VARIABLE INTAKE SYSTEM)

NOTE:
A = Hardwired









PRINCIPLES OF OPERATION

Variable Intake System
The flap valves can be set to one of two positions, to produce short or long intake tracts in the intake manifold. Short intake tracts are produced with the flap valves closed. Long intake tracts are produced with the flap valves open. The flap valves are closed at engine speeds up to 4700 rev/min and open at engine speeds of 4700 rev/min and above, with a hysteresis of 50 rev/min.
The intake manifold tuning valve receives a power feed from the power distribution box and is connected to ground through the ECM (engine control module). To close the flap valves, the ECM (engine control module) connects the intake manifold tuning valve to ground. The energized intake manifold tuning valve blanks off the atmospheric vent and opens the vacuum line between the cover plate and the pneumatic actuators. The depression in the intake manifold is sensed at the pneumatic actuators, which turn the drive shafts and move the flap valves to the closed position.
To open the flap valves, the ECM (engine control module) disconnects the ground connection and the intake manifold tuning valve is de-energized closed. Atmospheric pressure is sensed at the pneumatic actuators through the vent cap on the intake manifold tuning valve and the flap valves move to the open position.

Flap Valves Closed





Flap Valves Open