Air Induction System - Toyota 1 MZ–FE Manual

EG2–221
1MZ–FE ENGINE – SFI SYSTEM

AIR INDUCTION SYSTEM

Air filtered through the air cleaner passes through the MAF meter and the amount flowing to the
air intake chamber is determined by the throttle valve opening in the throttle body and the engine
speed. The MAF meter measures the intake flow to the engine by measuring the air's cooling
effect on the thermistor which is heated by the heater.
Located in the throttle body is the throttle valve, which regulates the volume of air intake to the
engine. Air intake controlled by the throttle valve opening is distributed from the intake chamber
to the manifold of each cylinder and is drawn into the combustion chamber.
At low air temperatures the IAC valve opens and the air flows through the IAC valve, as well as
the throttle body, into the air intake chamber. During engine warm up, fast idle is accomplished
by air flowing into the intake chamber via the IAC valve, even when the throttle valve is
completely closed. In this way the IAC valve controls the idle speed to suit the operating
conditions.
The air intake chamber prevents pulsation of the intake air, reduces the influence of the MAF
meter and increases the air intake volume. It also prevents intake air interference in each cylinder.
There is also the intake air control valve attached to the air intake chamber. Part of the ACIS, the
ECM provides signals to the VSV to open or close. This valve opens or closes the vacuum source
to the actuator, which in turn opens or closes the intake air control valve. The intake air control
valve is designed to modify the effective manifold length in 2 stages for increased power in all
driving ranges.