There's a suction tube next to the air filter. What's going on?
This is a tube in the crankcase ventilation system that re-directs the exhaust gas to the intake manifold for combustion. The engine of the car has a crankcase forced ventilation system, and when the engine is running, some gas will enter the crankcase through the piston ring. If too much gas enters the crankcase, the pressure of the crankcase will increase, which will affect the piston down, but also affect the sealing performance of the engine. Therefore, it is necessary to exhaust these gases in the crankcase. If these gases are emitted directly into the atmosphere, it will pollute the environment, which is why engineers invented the crankcase forced ventilation system. The crankcase forced ventilation system redirects the gas from the crankcase into the intake manifold so that it can enter the combustion chamber again. There is also an important part of the crankcase ventilation system, which is called the oil and gas separator. Part of the gas entering the crankcase is exhaust gas, and part is oil vapor. The oil and gas separator is to separate the exhaust gas from the oil steam, which can avoid the engine burning oil phenomenon. If the oil and gas separator is broken, it will cause the oil steam to enter the cylinder to participate in combustion, which will cause the engine to burn oil, and will also lead to an increase in carbon accumulation in the combustion chamber. If the engine burns oil for a long time, it may cause damage to the three-way catalytic converter.