Air Induction Systems: Turbocharger

WARNING: Turbocharger and related components operate at a very high temperature. Always allow system to cool or use proper protective clothing to prevent severe burns. For safety during road test, it is advisable to have a helper read tester.

CAUTION: Test duration during measurement should be limited to a maximum of 10 seconds. Before disconnecting or reconnecting turbocharger, thoroughly clean all joints, pipes unions and connections. Prevent dust and dirt contamination. Cover all components with dust-free paper or plastic. DO NOT use cloth or rags. Avoid nearby use of compressed air. DO NOT move vehicle or work in dusty conditions while turbocharger is open or removed.

NOTE: Ensure any engine related problems are corrected before testing turbocharger. Ensure no intake or exhaust system leaks exist. Engine oil temperature must be at least 176°F (80°C).

Disconnect wastegate by-pass regulator valve connector. Using a "T" fitting, install Turbocharger Tester (VAG 1397A) in intake manifold-to-Electronic Control Module (ECM) hose. Select measuring range II on turbocharger tester.
Road test vehicle in 3rd gear (M/T) or position 2 (A/T) at wide open throttle. Press "M" button on turbocharger tester when engine speed is 3500-4000 RPM. Read boost value. Boost value should be 7.25-9.43 psi (.51-.66 kg/cm² ).
If specified boost pressure is exceeded, go to step 4). If specified boost pressure is not obtained, check wastegate by-pass regulator and replace if necessary. Repeat turbocharger test. If specified boost pressure is still not obtained, replace turbocharger.
Check for blockage between wastegate by-pass valve and turbocharger. Check wastegate and operating rod operation. Ensure wastegate by-pass valve is securely mounted to turbocharger. Repair if necessary. Check for stuck wastegate by-pass regulator valve due to corrosion. If valve is stuck, replace turbocharger.