Air Intake System
The main components of the air intake system are air cleaner, mass air flow (MAF) sensor, air cleaner outlet hose, throttle body (with fast idle control system), idle air control (IAC) valve and intake manifold. The air (by the amount corresponding to the throttle valve opening and engine speed) is filtered by the air cleaner, then passes through the throttle body, then distributed by the intake manifold, then finally drawn into each combustion chamber. When the idle air control valve is opened according to the signal from ECM, the air bypasses the throttle valve through bypass passage and is finally drawn into the intake manifold. When the engine is cold, the fast idle control system increases the engine speed by opening the throttle valve to send the air to the intake manifold, and thus the engine is warmed up. See Fig 1 -Fig 4 .