Car maintenance tips: look at the color of car exhaust to identify faults

Black smoke
Trouble phenomenon:
carWhile driving, the engineexhaust pipeBlack smoke, exhaust pipe (silencer) There is an abnormal noise.
cause of issue:
The mixture is too rich, that is, the mixture in the cylinder is too much, the air coefficient is too small, and the combustion is incomplete. Part of the fuel is decomposed into free carbon and discharged from the exhaust pipe at high temperature, forming black smoke.
Incorrect ignition timing will also cause incomplete combustion of the mixture; or a few cylinders of the engine will not work, and a small amount of black smoke will be emitted.
Fault diagnosis and troubleshooting:
1. If the engine exhaust pipe emits a lot of black smoke, accompanied by the sound of shooting, it can be concluded that the mixture is too thick.Check whether the choke door is fully opened in time, and perform high-speed maintenance if necessary;CarburetorLook at the main nozzle. If oil is injected or dripped, the oil level in the float chamber is too high. Adjust to the specified range, tighten or replace the main measuring hole;air filterClogged, it should be cleaned or replaced.
2. If the engine exhaust pipe emits a small amount of black smoke, accompanied by a rhythmic "burst" sound, it can be concluded that a small number of cylinders are not working or the ignition timing is inaccurate. The cylinder-by-cylinder misfire method can be used to find out the cylinders that are not working, or to check and correct the ignition timing.
White smoke
Trouble phenomenon:
When a car is running, the engine exhaust pipe emits a lot of white smoke. One is milky white, and the other is steam white smoke with water droplets at the mouth of the exhaust pipe.
cause of issue:
When the engine is running, the exhaust pipe emits a large amount of white smoke. There are two situations:
The exhaust pipe discharges milky white oil mist. The main reason is the poor vaporization of fuel, which is discharged from the exhaust pipe without burning, and milky white smoke is formed. It is more common when the engine starts in winter, which is caused by low temperature and poor fuel atomization. It usually disappears as the engine temperature increases after the engine is started.
The exhaust pipe emits a large amount of water vapor and white smoke, and there are water droplets at the mouth of the exhaust pipe. The main reason is the water vapor formed by the cooling water jumping into the cylinder or the gasoline containing water.
Fault diagnosis and troubleshooting:
When a car parked in winter or rainy season starts for the first time, white smoke can often be seen. It doesn't matter. Once the engine temperature rises, the white smoke will disappear. This situation does not need to be overhauled. If the exhaust pipe becomes black smoke after the engine temperature rises, it indicates that the cylinder pressure is too low or individual cylinders are not working, and should be checked and eliminated.