Provided are methods for operating an internal combustion engine system including: an internal combustion engine provided with a plurality of cylinders, each of which being provided with an air inlet valve and an exhaust gas valve; a fuel supply system configured to supply fuel to the cylinders; an air intake system and an exhaust gas system; a turbocharging arrangement comprising an intake air compressor arranged in the air intake system and an exhaust gas turbine arranged in the exhaust gas system, wherein the intake air compressor is operatively connected to the exhaust gas turbine; a controllable gas feeding device arranged in the air intake system downstream the intake air compressor; an exhaust gas aftertreatment system arranged downstream the exhaust gas turbine; and a wastegate.