What Causes a Whistling Sound When Releasing the Accelerator in a Car?

[StMary]

During the process of releasing the accelerator in a car, a whistling-like sound may occur for the following specific reasons: 1. The engine temperature is too low. 2. Insufficient engine oil, leading to a lack of power. 3. Damage to the car's half-shaft, causing abnormal noise. 4. The engine belt is too loose, resulting in abnormal noise. Below is more information about releasing the accelerator in a car: 1. Turbocharger Working Principle: When the turbocharger starts working upon acceleration, it compresses a large amount of air and pushes it into the engine combustion chamber through the throttle. When the driver releases the accelerator pedal, the throttle closes. However, the turbocharger's blades do not stop working immediately. At this point, residual compressed air remains in the intake pipeline between the turbocharger and the throttle. If this air is not released promptly, the high pressure can damage the throttle and turbocharger blades. 2. Function of the Blow-off Valve: The blow-off valve's mechanism releases the residual compressed air in the pipeline when it detects excessive air pressure in the intake pipeline, thereby protecting the throttle and turbocharger blades. This also reduces turbo lag, making the engine work more smoothly. The 'whooshing' sound heard is the 'noise' produced when the blow-off valve releases the compressed air.