Idle speed rises and falls regularly.

One of the most common factors causing this situation is the serious carbon deposition in the throttle valve, which is also commonly known as traveling block. Therefore, before encountering idling jitter, there is no need to rush to repair the car, and the carbon deposit on the throttle can be solved.

Reasons for carbon deposition:

There are more or less residues in automobile gasoline, and there are also residues in the gas inhaled into the cylinder for combustion. When the combustible mixture of automobile gasoline and gas is burned, the unburned residue will produce honeycomb carbon deposit.

Part of the carbon deposit adheres to the surface of the combustion chamber and its piston rod, and the other part is scraped into the crankcase below by the piston rod. Carbon deposits entering the crankcase will pollute the oil and make it black.

Carbon deposition immediately occurred in the cylinder. How did it get to the accelerator?

The reason why the carbon deposit will run to the throttle valve is the unique design scheme of automobile engine-forced natural ventilation of crankcase (PVC valve). Because the engine crankshaft rotates rapidly in the crankcase, the working pressure in the crankcase will be higher. In addition, automobile gasoline can't burn completely all the time, and some gasoline vapor that can't catch up with combustion will rush into the crankcase.

The forced ventilation pipe of the crankcase connects the crankcase and the air inlet right in front of the throttle. Using the negative pressure generated by the breathing of the automobile engine and the burden in the crankcase, the natural steam that can't catch up with the combustion is sent to the crankcase for combustion again through the throttle valve according to the ventilation passage.

In all natural ventilation links, except the natural steam in the crankcase will pass through the throttle valve, the residual carbon and automobile oil hanging in the crankcase will enter the throttle valve according to the ventilation pipeline. When waiting for the vehicle speed, the throttle opening is small, which has a great impact on breathing, so the carbon deposit will gradually adsorb on the throttle.

The method of removing carbon deposit is cleaning.

Cleaning can be divided into omni-directional cleaning with the throttle removed and cleaning only the surface of the throttle. General direct injection engine manufacturers strongly recommend cleaning every 20,000 kilometers, and general indirect injection engines can be cleaned according to the situation. Nowadays, vehicles are all electronic throttles, and they can't pedal with steel cables. Therefore, after cleaning up the carbon deposit, the waiting angle of the throttle will not change, but the opening will increase. Therefore, it is necessary to calibrate and train the waiting angle of the throttle after cleaning it.

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