What is the problem with the exhaust pipe emitting blue smoke? Why is the exhaust pipe emitting black smoke?

Generally speaking, the exhaust gas from the exhaust pipe is almost colorless, but sometimes we can see that some car exhaust pipes will emit blue or black smoke. So what is the problem in this case?

What is the problem with the exhaust pipe emitting blue smoke?

Blue smoke is a sign of burning oil. If blue smoke is occasionally emitted from a cold car, it may be that the clearance between the piston and piston ring and the cylinder block is too large; if the car is hot and burning oil, it may be that the cylinder block and piston ring are worn, resulting in a decrease in air tightness, the valve oil seal is excessively worn, or the valve oil seal falls off and is damaged.

Also, cracked and worn valve guides will cause blue smoke from burning oil. Occasional and extremely slight blue smoke is not a big problem. Pay attention to checking the oil level on time. If blue smoke is often emitted, it is recommended to go to a repair shop or 4S shop for troubleshooting in time.

If too much engine oil is added, blue smoke may also appear. Also, if the exhaust pipe (Note: the exhaust pipe is not the exhaust pipe) that connects the engine to the outside world is blocked, causing the internal pressure of the engine to be too high, blue smoke may also appear.

Why is there black smoke coming out of the exhaust pipe?

Black smoke coming out of the car exhaust pipe indicates that the mixture is too rich. In layman's terms, there is too much gasoline, resulting in incomplete combustion.

The reasons for black smoke coming out of the car exhaust pipe are as follows:

1. The sensor or its circuit related to automobile fuel injection is faulty.

For example, water temperature sensor, throttle position sensor, intake pressure sensor (air flow meter), oxygen sensor, etc. When these sensors or their control circuits are faulty, the amount of fuel injected into the car will increase, causing black smoke to come out of the car exhaust pipe.

2. The vehicle's fuel supply system is faulty.

If the car's fuel pressure is too high or there is oil leakage from the fuel injector, the amount of fuel injected will increase, causing black smoke to come out of the car's exhaust pipe.

How to deal with black smoke from car exhaust pipe

1. Use a decoder to check whether the sensor is faulty.

If there is a fault code, check and repair it according to the prompt of the fault code. If there is no fault code, read the data stream to see if the data of these sensors are normal.

2. Check the fuel pressure.

Connect a fuel pressure gauge to the fuel line to see if the fuel pressure meets the standard. For most vehicles, the fuel pressure is about 2.5 bar at idle speed. As the throttle opens, the fuel pressure gradually increases. If the fuel pressure is greater than 2.5 bar at idle speed, it means that the fuel pressure is too high. Check whether the fuel pressure regulator and fuel pump are normal.

3. Check the fuel injector.

Remove the fuel injector and check if there is any oil leakage. If there is any oil leakage, clean or replace the fuel injector.