How is the throttle carbon deposit produced?

Carbon deposition in the engine is caused by insufficient mixing and combustion of "coke" or "sulfur" substances in gasoline with some engine oil entering the combustion chamber. Usually, the piston top, cylinder head top, spark plug, valve and exhaust pipe in the throttle are all dirty, but the dust is not filtered out. The main causes of carbon deposition in throttle are: 1, mainly from oil vapor, followed by heavy particles and moisture in the air. Even if the crankcase ventilation pipe is removed with a qualified air filter, the pollution speed of the throttle valve is still quite slow. 2. The crankshaft is built in the crankcase and connected with the oil pan. The working temperature of this part is about 100℃ ~ 180℃. Engine oil volatilizes when heated in use. The longer the use time, the higher the temperature and the stronger the volatilization. In addition, the compressed gas of the cylinder slightly presses on the crankcase through the gap of the piston ring, so an exhaust passage is needed. Otherwise, the oil bottom will generate positive pressure. 3. The reason why the crankcase ventilation pipe is connected with the throttle valve is that it is an environmental requirement on the one hand, and it deflates the crankcase through the intake negative pressure on the other hand. When the oily steam reaches the intake pipe, it becomes cold, and the oil inside condenses on the intake and throttle. At the same time, carbon deposits in steam also gather in these parts. The gap between throttle valves is characterized by large air flow, small space and low gas temperature, which makes it easy to condense.