Air Leak:
Waring: The troubleshooting guide may only be conducted with the vehicle in drivable condition. Please stop the trials at signs of engine malfunction such as black smoke, excessive oil consumption, or run-away engine.
Firstly, please check the following 4 points before inspection of the turbocharger.
1. Compressor housing outlet, intercooler circuit, and connections.
2. Turbine Housing inlet, manifold circuit, gasket, and connections.
3. Turbine Housing outlet, dump pipe circuit, gaskets and connections.
4. Compressor housing inlet, air filter clean situation and connections.
Second, check the preload process of the adjustable actuator as the following link.
Restricted exhaust:
The cause of low turbo boost pressure can be a result of a restricted exhaust as a result of having the turbo turbine connected and obstructing it. This then results in the need for the engine to push back against the exhaust with a larger force, decreasing the amount of energy that can be transmitted from the cylinders for engine power when driving.
How to spot it?
Please check the functions of the wastegate actuator. Signs that indicate bad news for your turbocharger is if the wastegate is immobile or does not close fully. At this point, one thing that you can try on the spot is to attempt to disconnect the wastegate and work the linkage by hand to check for binding and proper closure.