Do it at your own risk!
照例，抄襲網絡介紹：From autorepair.about.com
In a fuel-injected car, air is drawn in through the air intake. This is usually a long plastic tube going into the air filter housing. The reason the intake tube is long is to get the air moving in a fairly steady, coherent stream. It then passes through the air filter and then through an Air Flow Meter.
There are two types of AFM's, a vane type and a hot wire type. The vane type has a flap that is pushed by the income air. The more air coming in, the more the flap is pushed backed. There is a potentiometer attached to the flap that sends a voltage signal to the Powertrain Control Module (PCM). There is also a second vane behind the main vane that fits into a closed camber that dampens the movement of the vane giving a more accurate measurement. There is also an Air Temperature Sensor built into the AFM and works exactly as it did in the carbureted engine.
The hot wire AFM uses a series of wires strung in the air stream. The resistance of the wire at normal operating temperature is a known constant and will allow a set voltage through it. As the air passes the hot wire, it cools. As it cools, the resistance of the wire decreases allowing more voltage to pass through it. This voltage signal then goes to the main EFI computer and allows the adjustment of the fuel mixture. From the AFM it goes to the throttle chamber.
The throttle chamber controls the airflow into the engine. When it's closed, the car idles. There is a small bypass chamber that allows a small amount of air to bypass the throttle plate and go into the engine. By adjusting the amount of air through the bypass, we can adjust the idle speed of the engine. There is also a Throttle Position Sensor (TPS) mounted on the throttle plate that sends a signal to the main EFI computer telling it weather it is at idle, midrange cruising or wide open throttle. From the throttle chamber it goes through the intake manifold and into the cylinders.
One last component is the Cold Start Valve. It is electrically heated and performs the same function as the choke on a carburetor. The Cold Start Valve is a valve with a bi-metallic element that expands as it's heated. When it's cold, it allows a large quantity of air to bypass the throttle plate thus causing an increase in idle speed. As the element heats up, it closes the bypass passage and lowers the idle speed as the engine obtains normal operating temperature.
總而言之，言而總之，汽車air intake就是負責吸入新鮮空氣，提供給發動機燃燒汽油。
四大部件：air filter, mass air flow sensor(MAF) or air flow meter(AFM), throttle body, 和idle air control(IAC).
其他還有不少小玩意，俺就不在這裏露怯了。IAC 在我另一篇裏單獨介紹，所以這裏隻涉及三大部件。
打開車前蓋，大多有這麽一根粗大無比的長塑料筒子，這東西上下前後連著的東西加在一起，就是你的air intake system.
Throttle body, 你的氣門，就是油門。一根鋼纜控製氣門開關大小。你腳踩油門踏板，就在拉動這跟纜繩，控製氣門大小。所以，今後不要說踩油門，加油。應該是踩氣門，加氣，OK~~ 哈哈
粗塑料管子兩端的螺絲卡子鬆開，兩頭就都拔出來。連接原理跟烘幹機的排氣管道一樣。大管子上還連著幾根小管子，都拔下來，如果怕搞錯，就標記好。Throttle 上的電路可以斷開。如果不把Throttle 整體卸下來，那也可以不動電路。MAF最好拆下來清洗，所以電路斷開。
用手旋轉纜繩結構，打開throttle風門，裏邊看到黑乎乎的碳沉積和汙垢。我的不算太髒。相對這麽粗的管道，我懷疑這樣一點汙垢是否能影響功能。請老大們指點。
另外一端，看進去，管道中間伸出來的就是MAF sensor,線路結構在管道上邊。再裏邊，可以看到intake的air filter.
需要這些清洗劑，對號入座，不要搞錯。
Throttle拆下來可以清洗的徹底些。我的感覺不夠髒，懶得再拆，就翻開風門，直接大量噴throttle cleaner.我的車throttle安裝角度剛好合適，清洗劑和汙垢正好流出來，不會倒流進去。下邊要多墊些布，不要讓清洗劑汙染其他車內部件，尤其是皮帶。幾乎用完一整罐throttle cleaner，流出來的都是鐵鏽色的汙垢。網上見過有人用2罐洗一個throttle的。
流出來的清洗劑基本無色以後，停止噴洗。敞開風門晾幹。
拆另一側的MAF.需要特殊的socket set. 又忘記英文名稱了，反正汽車零件商店裏不難找。注意同樣是星狀socket，這個中間還要帶一個窟窿。有些是沒有窟窿地。此地停工15分鍾，去商店15刀砍一套新socket回家。
MAF螺絲擰開，拿下。用對應的cleaner狂噴一通。
下邊是一個簡單而重要的部件 --- air filter. 這個東西堵塞不暢，直接影響你發動機喘氣，會很無力地。一般filter藏在塑料盒子裏，盒子的固定鎖很像一般工具箱的掛扣，打開很簡單。
打開塑料盒子。有些車，什麽東西都不需要拆，直接就可以鬆卡子翻開換filter.
Filter正麵，看不出啥
Filter反過來，跟新的比較。記住，air filter對發動機影響很大，也容易汙染堵塞，所以應該經常檢查和及時更換。
Filter盒子底部也很多油泥汙垢
平頭螺絲刀從盒子底上刮出來的汙垢
老辦法，吸塵器，加一層擦手紙
刮鬆動filter盒子裏所有汙垢，然後，我吸！
清理好，裝上新filter.
蓋子扣回去
MAF插回去裝好
螺絲擰緊
檢查清洗劑汙染。有一點點，盡量擦幹淨。皮帶和飛輪上都沒有
所有管道連接安裝回去
我的air filter相對最髒，問題最嚴重，更換以後，發動機聲音和反應都得到明顯改善。
將來的想法是下邊這個酷東東。一個比較好的改裝kit 也就$150-200，相當於換不到10次普通filter價錢。這種up grade filter是life time use不用換。如果我還能開個3-5萬邁，這個東東應該非常合算，可以改進發動機表現和減少油耗，開的再久還可以節省air filter 價錢。不過據說這種cone filter有幹/濕兩種，不知哪種類型合適，那個品牌較好。另外，據說上邊吸氣痛快了，下邊exhaust也要相應加粗，不知道是不是必需。請有經驗的高人們指點一二。謝謝。
Update: 通過請教，換大流量filter的念頭打消了
 | • 請教 -橋盲- ♂    (80 bytes) (20 reads) 8/25/10 |
| • 沒有 -BigV8- ♂ (341 bytes) (72 reads) 8/24/10 |
