What are the symptoms of excessive carbon buildup in the car?

[EmilianoAnn]

The symptoms of excessive carbon buildup in the car are: reduced engine power, increased fuel consumption, and in severe cases, valve sealing issues due to cylinder carbon deposits. When there is excessive carbon buildup inside the engine, the gasoline sprayed by the cold-start injector will be largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making the engine difficult to start. In this situation, the engine will only start easily once the carbon deposits have absorbed enough gasoline to reach saturation. After starting, the gasoline adsorbed on the carbon deposits will be drawn into the combustion chamber by the engine's vacuum suction and burned, causing the air-fuel mixture to become overly rich. This fluctuation between lean and rich air-fuel mixtures leads to rough idling after a cold start.