Why does the car engine make a popping sound when shutting off?
2 Answers
Echo of unburned air and gasoline vapor. Here is relevant information about engines: 1. An engine consists of the engine block group, crankshaft connecting rod mechanism, valve train, fuel supply system, ignition system, cooling system, lubrication system, and starting system. 2. An engine is a machine capable of converting other forms of energy into mechanical energy, which can be used either as a power generation device or to refer to the entire machine including the power unit. 3. Types of engines include internal combustion engines (such as gasoline engines), external combustion engines (such as Stirling engines, steam engines), and electric motors.
I heard the mechanic explain this popping sound last time I got my car repaired. It's mostly caused by residual water vapor in the exhaust pipe. When the engine, which has been working at high temperatures, suddenly shuts off, the water vapor in the exhaust pipe quickly contracts upon encountering cold air, producing this sound. Another cause could be severe carbon buildup in the throttle body preventing it from closing properly, allowing the air-fuel mixture to rebound from the intake manifold at the moment of shutdown, resulting in a popping sound. A faulty carbon canister purge valve might also allow excess gasoline vapor to enter the intake system, burning on hot components and creating noise. I suggest you first check if the throttle body is dirty, as this is the easiest to address. If the sound occurs very frequently, it's best to inspect the exhaust system for leaks or carbon buildup issues, as these can affect the engine's health.
