Startup jitter of automobile cold car

1, the reason for carbon deposition is that the cold car starts to shake a few times and then turns off. Carbon deposition usually appears in the inner wall of throttle valve, intake valve head, intake port, piston top and combustion chamber.

2. Too much carbon deposit on the inner wall of the throttle will cause insufficient air intake, difficult starting or easy flameout at idle speed. After the water temperature reaches the normal working temperature of the engine, the computer repeatedly adjusts the position of the throttle valve plate, resulting in high and low idle speed;

3. In fact, the part that is most prone to carbon deposition is not only the throttle, but also the head of the intake valve (the end of the intake). The gasoline injection of indirect injection engine is injected into the intake space where the intake valve head is located, and gum, wax and unburned carbon compounds are deposited in this part. The surface of carbon deposit is loose and porous. After stopping for a night or a long time, when the cold car is started, most of the fuel injected by the injector is absorbed by carbon deposits. The amount of fuel entering the cylinder is insufficient, and the mixture is thin and difficult to ignite. The motor is running, and the fuel entering the cylinder is enough to ignite after multiple injections. In this case, it will certainly be difficult to start;

4. More seriously, if there is too much carbon deposit on the head of the intake valve and the valve is not closed tightly, it will make the cold start more difficult. Even if it can be barely started, it will be closed soon. Moreover, with the increase of engine temperature, the fuel in the carbon deposit evaporates and is sucked into the cylinder to participate in combustion. This part of the fuel is out of control, resulting in too much mixture and poor engine work.