Control strategy for counteracting incipient turbocharger surging using a variable valve actuation mechanism for through-cylinder bleed

An internal combustion engine comprising:

• an intake system through which charge air is delivered to an intake manifold of the engine, including a turbocharger that comprises a compressor operated by exhaust gases from the engine for delivering compressed charge air into the intake manifold;
• intake valves that are normally closed but open at times during engine operating cycles to allow charge air to enter combustion chambers of the engine from the intake manifold;
• exhaust valves that are normally closed but open at times during engine operating cycles to allow the exhaust gases to exit the combustion chambers;
• a control for controlling the opening of the exhaust valves in relation to engine operating cycles and for controlling fueling of the engine in relation to engine operating cycles;
• wherein, at times, the control further retards the opening of the exhaust valve opening during engine operating cycles to cause the turbocharger to increase pressure in the intake manifold, increases engine fueling in relation to the increased pressure in the intake manifold, and in response to any incipient surging of the compressor resulting from such further retarded exhaust valve opening and such increased engine fueling, causes the exhaust valves to be open, during at least some portion of the time that the intake valves are open, for bleeding a sufficient amount of charge air through the combustion chambers to the exhaust system to counteract incipient compressor surging.