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About carbon deposit

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What is the cause of carbon deposition?

1. During the normal operation of the engine, the engine oil of the gasoline and the normal combustion engine cannot be completely burned in the cylinder under the condition of insufficient oxygen supply, and the particles of the soot and the lubricating oil are burnt. When the engine continues to run, it is further oxidized to become colloidal. Firmly adhered to the top of the piston, the piston ring, the back of the valve, the inner face of the intake pipe, the throttle body and the combustion chamber, and so on. Under the repeated action of high temperature, the gum is changed into asphaltene, resinous and carbonaceous, thereby forming carbon deposits.

2. Crankcase ventilation setting. To prevent polluting the air, automotive design engineers direct the exhaust from the engine directly into the intake manifold and enter the combustion chamber with fresh air for combustion. The high temperature oil vapor fills the intake manifold with fresh air, one part is attached to the pipe wall and the valve back, and the other part is mixed with the injected fuel at the intake valve to form a mixed steam with the intake air flow, and is discharged after entering the combustion chamber for combustion. Outside the car.

3. During the storage and transportation process, gasoline is easily oxidized with air to form a gelatinous substance, or the content of the rubber itself is very high (the quality of gasoline is poor). These gums enter the fuel supply system of the vehicle with the gasoline. Inside the combustion chamber, and then burning with the gasoline, it will cause a lot of carbon deposits and oil stains in the fuel supply system, the engine combustion chamber, the piston ring groove, the spark plug, the intake valve back, the intake port and other parts. Wait.

4. Congested urban road conditions, so that the vehicle is always in a stop-and-go state, the engine can not operate at high speed, and the fuel or the lubricating oil that enters the combustion chamber cannot be burned 100%. The unburned part of the oil is in the role of high temperature and oxygen. The gel is formed underneath, adheres to the surface of the parts inside the engine, and then forms a carbon deposit by high temperature.

5. According to the control characteristics of the EFI engine, the cylinders are injected and re-ignited every time they work. When we extinguish the engine, the ignition is cut off immediately, but the gasoline sprayed in this work cycle cannot be Recycling can only be attached to the intake valve and the combustion chamber wall. Gasoline is easily volatilized, but the wax and gelatin in the gasoline are left behind. In the long run, the wax and colloid in the gasoline are thicker and thicker. When it is heated, it hardens to form carbon deposits.

In short, it is inevitable that engine work produces carbon deposits and oil stains, but when the carbon deposits in the engine is too much, the engine will work poorly and cause different failure phenomena.

What is the danger of carbon deposits?

The coke in the combustion chamber has a great influence on the normal operation of the engine, such as causing the valve to be closed, the intake valve or the exhaust valve to leak, and knocking. Especially for knocking, the actual volume of the cylinder becomes smaller due to the serious accumulation of carbon, the compression ratio increases, and at the same time, in the high temperature environment, the carbon deposit will always burn red due to the poor heat dissipation capability, so that the high temperature compressed mixture is ignited by the spark plug with timing. It can also be randomly ignited by the high temperature coke in the cylinder to produce knocking.

How to prevent carbon deposition?

Regular maintenance, keep the oil and gas lines clean; it is recommended to clean the air grid every 5000-10000km (according to the use and actual conditions of the vehicle) (replace according to the actual situation), clean the throttle and clean the burner; every 15000-25000km (According to the use and actual conditions of the vehicle) Clean the intake pipe throttle combustion chamber and related oil passages, check the diesel filter condition for replacement; strengthen your driving level, avoid idle idling for a long time, avoid turning off the fire immediately after high-speed driving, avoid starting Immediately after high speed, avoid low speed shifting.