bosch k與ke噴射引擎系統控制元件

汽車引擎從早期的化油器時代進入噴射引擎，BOSCH 噴射引擎(Gasoline Fuel-Injection
System K-Jetronic)的架構為多家汽車公司採用，這階段的噴射控制元件主要利用材料的溫度延展特性來控制引擎燃油噴射壓力，隨著電子控制工業的發展與進步，發展商又於原有的 K-Jetronic(台灣稱為機械噴射系統)加上電子控制元件，希望藉著電子控制元件來提升引擎的燃燒效率
Gasoline Fuel-Injection System KE-Jetronic(台灣稱為電子噴射系統又稱半機械半電子噴射系統)，雖然多加了電子控制元件，例如差壓閥、含氧感知器、空氣流量感知器、ICU等多個偵測元件，但電子元件放置於高溫的引擎工作環境，但隨著時間容易產生電阻、電壓的不穩定變化，汽車引擎的調教就變得比機械噴射系統更複雜。
K-Jetronic與 KE-Jetronic引擎系統控制元件有哪些差別，從下圖大概可略知一二。
經驗上要改善引擎的功能，這些電子控制元件及連結的線路、插座必須先確認是沒有問題的，再來調整燃油壓力與油氣混合比，才不至於花太多冤枉錢，但也不可能完全不花錢買經驗。

K-Jetronic

KE-Jetronic

引擎系統有關的重要零件

分油盤外部周邊O型環

賓士老車的燃油通道車主常常為改善引擎效能，添加油道清潔劑、改良劑，這些化學品均號稱不傷塑膠材料，但長時間下來真的不傷引擎及油道內部非金屬零件嗎？
分油盤O型環長時間浸泡在汽油裡，雖著時間材料本身就會起變化(膨脹、失去彈性)，在加上三不五時添加清潔劑，慢慢的就會變形滲漏。引擎約25萬公里上下就必須更換內部O型環，由其是噴油嘴，所以引擎室的大部分O型環都必須耐酸鹼及耐高溫。
當然德國原廠有提供零件但是貴鬆鬆。

那麼分油盤不用更換嗎？

當然要，但為什麼沒有保養場願意換.......
因為第一拿不到原廠零件，第二因為很麻煩萬一沒裝好怎麼辦(不好意思....修車幾十年從來沒分解過分油盤)。

分油盤外部滲漏分為3個部分：
1.差壓閥滲漏：
如果差壓閥本體滲漏就不用修了，直接更換新品。除了燃油燃燒不穩外也容易發生危險，3年前新品一顆3800元，2014年一顆6000元上下。另外與分油盤連接的兩個油孔有兩個O型環一段時間就會滲漏，因位置在分油盤後方不易察覺，每年應該檢查一下。

2.分油盤底部密封O型環:
這個零件主要提供阻絕燃油及空氣進入歧管內，容易汙染分油盤柱塞行進動作，空氣的進氣量測也會受影響。拆下分油盤看看柱塞位置應該卡滿油汙，檢查看看O型環是否完整，大部分的車子這個零件重新車一直用到現在，當然有一部分車子遺失了也不知道。

3.分油盤柱塞行程調整螺絲O型環：

一般分油盤的柱塞(中間的圓棒)拆下分油盤觸控必須能自由進出，如果不能進出，燃油量的大小將不能隨壓力調整(可先量測分油盤上下室壓力)，要進一步判斷問題勢必要分解分油盤，看看是否膜片破裂穿孔、或柱塞套筒O型環滲漏、或彈簧變形等其他原因....事情就比較大條......。

柱塞行程調整螺絲控制柱塞的行進距離，可以用尖嘴鉗旋轉下來更換O型環，螺絲表面距離柱塞套筒最外緣的距離為0.6mm(原廠設定值)，拆下調整前最好用油標尺先量測原來的距離，再來更換O型環。
這個壓力O型環有安裝的方向，不能硬裝，舊的拆下前先觀察安裝位置(先拍照紀錄)，新的裝上崁入調整螺絲前必須確定方向，然後上點潤滑油慢慢將螺絲旋入柱塞套筒至預定位置。
內漏的分油盤柱塞行程調整螺絲O型環會造成油氣過濃熱車不易發動。

下圖O型環從上至下依序為:

1.差壓閥O型環2個
2.分油盤柱塞行程調整螺絲O型環1個
3.分油盤底部密封O型環1個

這部分的零件更換車主可以自行安裝，但拆分油盤時請先於分油盤下方放置乾淨的布，拆油管接頭時，管內有壓力燃油會噴出來。
順便看看節氣門真空管接頭是否脫落。

重要的燃油系統零件

節氣門與微調開關-----w126 Throttle

節氣門是負責引擎空氣進入的重要機構，零件的構成大約可以分為：連桿、閥體、訊號線3個部分，一般車主大約每10000公里會請保養廠清潔節氣門及怠速馬達，但節氣門的保養如果只是由空氣流量總成噴入泡沫清潔是不夠的。

下圖是節氣門連結點火放大氣與引擎溫度感知器通氣管的接頭，在蝴蝶頁內側有3個通氣孔，因為會吸入引擎的油氣常常會堵塞，無法用泡沫徹底清潔，再加上蝴蝶頁的轉軸容易卡油垢，如果可以請多花一點代價請師傅拆下流量總成來清潔，順便量測一下訊號線的電組是否正常。又是一個很貴的零件。

節氣門連桿的黃銅球狀接頭每年必須潤滑清潔一次，以免連桿突然卡死。
電子微調開關彈性有其使用年限，時間一到你會發現怠速時引擎轉速會突然增加時好時壞，這時後檢查一下這個零件的彈性。不要換了一堆零件還是無法解決怠速的問題。

重要的進氣系統零件

汽油幫浦逆止閥

燃油幫浦逆止閥的作用是防止燃油於引擎關閉時，燃油回流導致燃油管內壓力不足，引擎不易發動。尤其是在熱車時不易發動，就是因為管內壓力不足所導致。
假如車輛能點火但就是無法發動引擎，在排除燃油幫浦繼電器故障及敲擊燃油幫浦還是不能發動時，請先檢修逆止發是否正常，因為更換燃油幫浦要4000元，但更換逆止發只要幾百元。

逆止閥故障的前兆

燃油壓力不足低
當燃油幫浦的逆止閥不良，不能夠維持壓力的適量，車輛容易熄火。燃料壓力計可以用來測試在車輛行駛時的燃料壓力的量。如果壓力的量小於規格，單向閥可能需要更換。

行進間熄火失速
如果燃油幫浦的逆止閥不良，車輛可以正常啟動，但只要燃油幫浦關閉，車輛就會熄火。這是由於缺少壓力，這使得燃料回流到燃油幫浦內。

無法啟動
如果逆止閥壞了，汽車可能無法啟動。汽車無法啟動，但如果旋轉鑰匙重複這個過程幾次，還是可以累積足夠的壓力，使車輛啟動。這樣的情形單向閥需要更換。

燃油系統重要零件

冷車噴油嘴的問題:Problem with cold start injector

冷車不好發動及油耗過大可能的原因之一，因為引擎溫度訊號不良或是靈車噴油嘴堵塞或內漏。拆開來測試看看，原廠零件不便宜，大部分的保養廠商都會少裝一個零件可能導致漏真空。

 Problem with cold start injector / thermal time switch circuit 

The cold start injector provides a brief blast of fuel only when the starter motor is running (when the key is in position III). It operates based on info from a thermal time switch, which tells the cold start injector when the engine is cold. If the engine is warm, the thermal time switch breaks the circuit and the cold start injector doesn’t fire.

Testing the cold start injector is fairly easy. Just remove it from the intake manifold (and make sure to bolt down the ground wires again). Now have a friend start try to start the car while you hold the cold start injector in a small bottle or napkin or some such. If it sprays out fuel, you’re good to go. If it doesn’t, then you’ve got a problem.

The best way to try and solve this problem of whether it’s the cold start injector or the thermal time switch causing the problem is to get out your voltage meter and hook it up across the two little plugs in the plug that hooks up to the cold start injector. If, when you start the car, you get 12 volts across the cold start injector plug, then the thermal time switch is working and the cold start injector is faulty. If you don’t get 12 volts across the plug, then the thermal time switch needs to be replaced.

Cold-start valve

Parts:
1. Electrical connection
2. Fuel supply with strainer
3. Valve (electromagnet armature)
4. Solenoid winding
5. Swirl nozzle
6. Valve seat

The cold-start valve
The cold-start valve  is a solenoid-operated valve. An electromagnetic winding is fitted inside the valve. When unoperated, the movable electromagnet armature is forced against a seal by means of a spring and thus closes the valve. When the electromagnet is energized, the armature which consequently has lifted from the valve seat opens the passage for the flow of fuel through the valve. From here, the fuel enters a special nozzle at a tangent and is caused to rotate or swirl.The result is that the fuel is atomized very finely and enriches the mixture in the manifold downstream of the throttle valve. The cold-start valve is so positioned in the intake manifold that good distribution of the mixture to all cylinders is ensured.

Thermo-time switch
The thermo-time switch limits the duration of cold-start valve operation, depending upon temperature.The thermo-time switch consists of an electrically heated bimetal strip which, depending upon its temperature opens or closes a contact. It is brought into operation by the ignition/ starter switch, and is mounted at a position which is representative of engine temperature. During a cold start, it limits the “on” period of the cold-start valve. In case of repeated start attempts, or when starting takes too long, the cold-start valve ceases to inject. Its “on” period is determined by the thermo-time switch which is heated by engine heat as well as by its own built-in heater. Both these heating effects are necessary in order to ensure that the“on” period of the cold-start valve is limited under all conditions, and engine flooding prevented. During an actual cold  start, the heat generated by the built-in heater is mainly responsible for the “on” period (switch off, for instance, at –20 °C after 7.5 seconds). With a warm engine, the thermo-time switch has already been heated up so far by engine heat that it remains open and prevents the cold-start valve from going into action.

賓士機械噴射引擎故障排除：K-Jetronic cis Troubleshooting

機械噴射引擎保養維修因為不像電子噴射引擎可以讀取故障碼，引此維修上就必須根據狀況來一一檢查零件的妥善性，才能排除問題，還好老車的關鍵零件就那幾個。

汽車故障維修對照表:

避免因為翻譯的錯意，特將車友"dudeperson3"的機噴維修心得原文引用(適用w126、w124、w201)資料來源：http://www.benzworld.org/forums/5378229-post1.html

If the Engine turns but won't start

1: No fuel pressure, or less than 50 PSI. Test the fuel pump (all 190s) and pre-pump (of those 190s that have two pumps) and do a fuel pressure and volume test.

2: Jammed and/or sticking airflow sensor. Remove the air cleaner and loosen the center line on fuel distributor. This will relieve the control pressure. Press down on the center of the plate and you should feel no resistance or binding. 

3: Defective cold start injector. If the injector does not function, the air-fuel ratio will be lean, preventing easy start up...tho, it may still start.

4: Shorted or defective thermo time switch. The cold start injector will not work if the thermo time switch is defective. Check this in the event that your cold start injector does not function before replacing. (I personally was not aware of this, nor do I know where it is, but I trust them)

5: Control plunger sticking. Remove the fuel distributor from the airflow sensor and check to see if it moves freely. (I can't imagine this actually happening)

6: Restricted injectors. For this to be the cause, they would have to be severely restricted, which is why it is listed last. Do an injector flow test and ensure that the delivery is near equal.


Hot starting difficulty

1: Loss of rest pressure. Do a pressure test and focus on the rest pressure. If it does not pass, check for a defective fuel pump check
valve, defective (or clogged) fuel distributor, faulty system pressure regulator, and leaking cold start injector.

2: Airflow sensor adjusted incorrectly. Check height, centering and for binding. Remove the boot and loosen the center line on fuel distributor to
relieve control pressure.

3: Sticking or binding of the control plunger. Remove the fuel distributor and ensure that the control plunger moves freely.

4: Injectors leaking. Remove the injectors from the intake manifold and with the ignition key on and engine off, press on the center plate to pressurize the system. Inspect and replace any injector that is leaking.

5: Cold start injector leaking. Same test as above.

6: Shorted thermo time switch. Cold start injector is dependent of this component.

7: Incorrect control pressure. Do a pressure test and verify that the warm control pressure is within spec.

Rough idle (cold)

1: Cold control pressure incorrect. The movement of the control plunger will be limited if the cold control pressure is too high. This in turn will limit the amount of fuel able to be delivered through the injectors. The result will be a lean ratio and will cause rough idle.

2: Auxillary air valve defective. If defective and not opening, idle cannot rise and results in rough idle. (I think I have this issue in my 2.3)

3: Airflow sensor adjusted improperly or binding. If the movement is not smooth, it will result in air-fuel ratio errors. If you've never messed with it, and no one else has, then just check for binding or extra resistance (mechanical resistance).

4: Leaking cold start injector. If the cold start injector is leaking, the engine will be over-fueled even if cold. If the cold start injector is leaking, the idle will get worse as the engine temperature increases.

5: Injectors have an unequal flow or spray pattern. Do an injector flow test and replace any that do not deliver the correct amount of fuel or have a poor spray pattern. 

Runs rough (warm)

1: Warm control pressure incorrect. Incorrect warm control pressure that is too high or low will cause an incorrect air-fuel ratio, thus resulting in a rough idle.

2: Airflow sensor adjusted improperly or binding. If the movement is not smooth, it will result in air-fuel ratio errors. Check for centering and correct rest height. (again, its more likely that its binding if no one has ever messed with it)

3: Leaking cold start valve. Again, will result in over-fueling the engine, resulting in a rough idle.

4: Injectors have an unequal flow or spray pattern. Do an injector flow test and replace any that do not deliver the correct amount of fuel or have a poor spray pattern.


Stalls after starting (warm)

1: Warm control pressure. If the warm control pressure is too high, the air-fuel ratio will be lean.

2: System pressure incorrect. If too high or low, the air-fuel ratio will be incorrect.


Idle speed high

1: Check auxiliary air valve. Ensure that it is closing. (Not quiet sure how to do that)

2: Vacuum leaks. Self explanatory, I hope. I'd start with the Air Flow meter and the boot below it, then all the connections on the intake manifold, and then the manifold/head connection. Also, all vacuum lines. 


Backfire in intake

1: Check that CO adjustment is correct. If incorrect, backfire will result if started and under a load. (I'm not sure how to do that)

2: Boot between airflow sensor and throttle defective/leaking. Will result in a lean mixture due to extra air. Our cars are old, its rubber. It might have cracked. 

3: Vacuum leaks. Self explanatory.


Misfires

1: Ignition. Inspect the cap, rotors, wires, and plugs.

2: Fuel delivery inadequate. Check for binding of airflow sensor, control plunger, incorrect control or system pressure and restricted injectors.

3: Injectors. Unequal delivery or poor spray pattern. Do a test and
replace any that are defective. 


Poor power

1: Control pressure too high. If the control pressure is too high, the control plungers travel will be limited, resulting in a lean running engine.

2: Check ignition components. Verify that the spark plugs, wires, cap and rotor are not worn, dirty, or defective.

3: Injectors restricted. Do a test for delivery. If an injector is restricted, fuel delivery will be limited, thus power will suffer.


Sag or stumble when accelerating

1: Airflow sensor plate binding or sticking. If binding or sticking, fuel flow will be limited.

2: Control plunger binding or sticking. If binding or sticking, fuel flow will be limited.

3: System pressure or warm control pressure incorrect. If too high, the travel of the plunger will be limited.

4: Injector flow unequal. Self explanatory.


Fuel consumption high

1: Air-fuel ratio incorrect

2: Injectors leaking

3: Cold start injector leaking

燃油系統的重要零件