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The wastegate on a turbocharger prevents over-boost conditions and helps to reduce turbo lag.
The wastegate can be controlled by a vacuum actuator or an electronic solenoid. Both systems require a preload adjustment of the rod attached to the arm on the wastegate. If the rod is not adjusted when the actuator or turbocharger is replaced, it can cause the valve to leak or not open enough. Andrew Markel discusses how to diagnose a wastegate actuator and perform a pre-load adjustment. This video is sponsored by MAHLE.