Air Induction System
Main components of 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.
Air (by amount corresponding to throttle valve opening and engine speed) is filtered by air cleaner, passes to throttle body, is distributed by intake manifold and finally drawn into each combustion chamber. When IAC valve is opened according to signal from ECM, air bypasses throttle valve through bypass passage and finally drawn into intake manifold.
When engine is cold, fast idle control system increases engine speed by opening throttle valve to send air to intake manifold, and thus engine warm up. To identify air intake system and fast idle control, see Fig 1 , Fig 2 or Fig 3 .