Is it normal to have black water in the exhaust pipe

If a small amount of black smoke is emitted from the exhaust pipe of the engine, accompanied by rhythmic "sudden" sound, it can be concluded that a few cylinders are not working or the ignition timing is misplaced. The misfire method can be used to find out which cylinders are not working or to check and correct the ignition timing. Black water in the exhaust pipe is definitely abnormal: 1. Black water is discharged from the automobile exhaust pipe because the water vapor in the exhaust pipe condenses into water and mixes with the carbon deposit in the exhaust pipe; 2. Gasoline will form water and carbon dioxide after burning, and water vapor will be formed at high temperature; At low temperature, it condenses into water. When the ambient temperature is high, the water vapor has been discharged before condensation; When the ambient temperature is low, water vapor will condense into water droplets on the exhaust pipe wall and flow out with the exhaust gas; 3. At this time, the black water drips because the water vapor condenses into water and mixes with the carbon deposited in the exhaust pipe; As long as it is a car burning gasoline, the exhaust pipe will turn black after a long time. This is because it is impossible for any fuel in the world to achieve the so-called 100% complete combustion. At most, it is fully burned, so these non-combustible impurities in gasoline will be discharged and accumulated in the exhaust pipe to form black carbon. Especially if the exhaust pipe shakes, it is easy to loosen the previous carbon deposit.