Controlling Exhaust Gas Recirculation in a Turbocharged Engine System

Methods and products for controlling exhaust gas recirculation. A target total EGR fraction is determined for compliance with exhaust emissions criteria, and a target pressure/low pressure EGR ratio is determined to control engine knock. When used in an engine system having only one EGR path the EGR ratio is set to 100% high pressure EGR and 0% low pressure EGR.