How to check the air leakage in the air intake system

The inspection method of air leakage in the air intake system is as follows: 1. Inflating method: Apply soapy water to the relevant parts of the air intake system, then fill compressed air into the intake pipe of the gasoline engine with a hose, and observe or feel whether the hose and connector are leaking by hand; 2. Open the air inlet pipe in front of the throttle, then start the engine to run at a constant speed, and then block the air inlet of the throttle body with cardboard. If the engine does not turn off, it means that the intake pipe is leaking; 3. Water addition method For older gasoline engines, the "water addition method" can be used, that is, when the gasoline engine is running at a constant speed, it is said that the water is in the suspected air leakage part of the intake system, and whether there are bubbles there; 4, spray method in a quiet environment, if auscultation is faintly visible "; The hiss of intake air indicates that there may be air leakage at the joint of intake system, and carburetor cleaner can be used to spray the possible air leakage. If the engine speed increases obviously, after stopping spraying carburetor cleaning agent, the engine speed decreases slowly, and then the engine speed increases again, indicating that there is air leakage here. If the engine speed does not change after spraying, the seal is good.