Subaru LEGACY 2002 Quick Reference Index page 61

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 AND AIR TEMPERATURE SENSORS
The intake manifold pressure sensor and the intake air temperature sensor are integrated into a
single unit. The unit is mounted on the intake manifold and measures the absolute air pressure in
the intake manifold as well as the temperature of the intake air.
The measured pressure and temperature are converted into electrical signals and sent to the
ECM. The ECM uses these signals to control injection and ignition timing as well as the fuel injec-
tion amount.
(1) Pressure sensor
(2) Intake air temperature sensor
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.
AIR LINE
FU-3
Fuel Injection (Fuel System)
H2H2825B