Why could a turbocharger be surging?

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall.

Common conditions that result in compressor surge on turbocharger gasoline engines are: * A compressor bypass valve is not integrated into the intake Plumbing between the compressor outlet and throttle body * The outlet plumbing for the bypass valve is too small or restrictive * The turbo is too big for the application