What is the sound like air being released when releasing the accelerator pedal?
2 Answers
Releasing the accelerator pedal produces a sound similar to air being released, which is the sound of the pressure relief valve working. Below is an explanation of the reasons: 1. Turbocharger working principle: When the turbocharger starts working during acceleration, it compresses a large amount of air and pushes it through the throttle into the engine combustion chamber. When the driver releases the accelerator pedal, the throttle closes. However, the turbocharger blades do not stop working immediately. At this time, there is still residual compressed air in the intake pipe between the turbocharger and the throttle. If this air is not released in time, the high pressure can damage the throttle and turbocharger blades. 2. Function of the pressure relief valve: The valve of the pressure relief valve will release the residual compressed air in the pipe in time when it detects excessive air pressure in the intake pipe, thereby protecting the throttle and turbocharger blades. This also reduces turbo lag and makes the engine work more smoothly. The sound of air being released is the "noise" produced when the pressure relief valve releases the compressed air.
I've also encountered a hissing sound when releasing the throttle while driving, which might be the turbocharger at work. When the engine is equipped with a turbo, the throttle valve closes immediately upon releasing the accelerator, but the turbo is still spinning. The compressed air needs somewhere to go, so the blow-off valve opens to release the air, creating that 'hissing' sound. This is actually quite normal and indicates the turbo system is functioning. However, if the sound becomes unusually loud or changes pitch, it might be worth checking for air leaks in the pipes or potential turbo malfunctions. Once on the highway, I heard an abnormal noise, and upon inspection, found a small crack in the intake hose—replacing it fixed the issue.
