Air Line - Subaru LEGACY 2002 Quick Reference Index

AIR LINE

Fuel Injection (Fuel System)
2. Air Line
A: GENERAL
The air filtered by the air cleaner enters the throttle body where it is regulated in the volume by the
throttle valve and then enters the intake manifold. It is then distributed to each cylinder where the
air is mixed with fuel injected by the injector. During idling operation, air flows into the cylinder
through the idle air control solenoid valve, bypassing the throttle valve. This enables controlling the
engine idling speed properly.
B: INTAKE MANIFOLD PRESSURE SENSOR
The intake manifold pressure sensor is attached to the top of the throttle body, and continuously
sends to the engine control module (ECM) voltage signals that are proportional to intake manifold
absolute pressures. The ECM controls the fuel injection and ignition timing based on the intake
manifold absolute pressure signals in addition to other signals from many sensors and other con-
trol modules.
B2H3905A
C: THROTTLE BODY
In response to operation of the accelerator pedal, the throttle valve in the throttle body opens/clos-
es to regulate the volume of the air drawn into the combustion chamber.
During idling, the throttle valve is almost fully closed and the volume of air passing through the
throttle body is less than that passing through the idle air control solenoid valve.
More than half of the air necessary for idling is supplied to the intake manifold via the idle air con-
trol solenoid valve which controls properly the engine idling speed, so the idling speed needs not
be adjusted.
FU-3