Is the Turbocharger Blow-off Valve Open or Closed at Idle?
2 Answers
At idle, the turbocharger blow-off valve is in a closed state. When the system's boost pressure exceeds the set pressure, the blow-off valve will open. Introduction to Turbocharging: Simply put, turbocharging is about burning gasoline more thoroughly, primarily by significantly increasing the air volume mixed with gasoline. Therefore, modern turbocharged engines are very powerful but also consume more fuel, without showing significant gasoline savings. Advantages of Turbocharging: It increases the engine's air intake, thereby enhancing the engine's power and torque. After boosting, it can output greater power. Moreover, the pressure and temperature during engine operation are significantly increased.
The idle turbocharger blow-off valve is typically closed. When the engine is idling, the RPM is very low, around 800 to 1000 revolutions per minute, and there is almost no exhaust gas flow generated. The turbocharger hasn't started working yet, so there is no excess boost pressure that needs to be released. Therefore, the blow-off valve remains closed to prevent air leakage or uncontrolled entry into the intake manifold system. If it were open, air would escape through the valve, potentially causing unstable idling, surging, or increased fuel consumption, and it could also damage the turbocharger and related engine components. When I was driving myself, I once encountered a stuck valve issue—the car shook violently at a red light, and upon inspection, it turned out the valve was abnormally open. Maintenance advice is to pay extra attention to the engine sound during cold starts; any unusual noise is worth suspecting. Regularly visiting a repair shop to scan electronic control signals with diagnostic tools can prevent minor issues from escalating. When modifying the turbo system, ensuring proper valve selection and regular cleaning can extend its service life.
