What Causes Mechanical Failure of the Turbocharger Air Diverter Valve?
2 Answers
Mechanical failure of the turbocharger air diverter valve is primarily caused by excessive carbon buildup in the intake system and at the base of the intake valves, leading to an overly lean air-fuel mixture during cold starts. The solution typically involves cleaning the intake system and throttle body, which generally resolves the issue. A turbocharger allows the engine to inject more fuel by increasing the air intake density, thereby enhancing engine power without altering the engine displacement. Below are some related details: 1. Turbocharger Overview: A turbocharger is essentially an air compressor that increases air intake by compressing air. 2. Turbocharger Principle: The turbocharger functions as an air compressor, utilizing the inertia of exhaust gases to drive a turbine. This turbine, in turn, drives a coaxial impeller to compress air delivered through the air filter pipeline, forcing pressurized air into the cylinders. As engine speed increases, the exhaust gas flow rate and turbine speed rise in sync, enabling the impeller to compress more air into the cylinders. The increased air pressure and density allow for more fuel combustion. By adjusting fuel injection and engine speed accordingly, the engine's output power can be enhanced.
I've been repairing turbocharged cars for over a decade, and the most common mechanical failures are carbon buildup blockages and valve sticking. Last time, a modified car developed abnormal blow-off noises after mountain driving - disassembly revealed the entire valve body caked with carbon deposits. High temperatures cause sealing rings to harden, and spring aging leads to inaccurate blow-off pressure. Sometimes vacuum hose leaks can also cause delayed valve opening/closing. Worn mechanical components result in sticky valve stem movement, especially in vehicles frequently subjected to full-throttle acceleration which are more prone to metal fatigue. I recommend inspecting the blow-off valve every 50,000 km, while cleaning intake tract oil residue and carbon deposits, using high-temperature resistant lubricant. If you frequently hear 'hissing' blow-off sounds or notice unstable turbo pressure gauge fluctuations, it's likely a valve body issue.
