Method and system for vacuum control

A method for an engine, comprising:

• operating the engine with exhaust gas recirculation;
• and
• in response to a vacuum requirement,
• reducing an opening of each of a post-catalyst exhaust throttle and an EGR valve to increase exhaust flow through an EGR cooler and then through an exhaust ejector;
• and
• drawing vacuum at the ejector.

An engine system, comprising:

• an engine including an intake and an exhaust;
• a throttle downstream of a catalyst in the engine exhaust;
• an exhaust gas recirculation (EGR) system including an EGR take-off for recirculating catalyst-treated exhaust gas from upstream of the exhaust throttle to the engine intake, the EGR take-off including an EGR cooler upstream of an EGR valve, and a bypass passage coupling an outlet of the EGR cooler with the engine exhaust, downstream of the exhaust throttle, the bypass passage including an ejector;
• and
• a controller with computer readable instructions for:
• operating the engine system in a first EGR mode with the exhaust throttle more open to recirculate a portion of exhaust gas to the engine intake while directing a first, smaller amount of exhaust gas through the EGR cooler and then through the ejector;
• and
• operating the engine system in a second EGR mode with the exhaust throttle more closed to recirculate the portion of exhaust gas to the engine intake while directing a second, larger amount of exhaust gas through the EGR cooler and then through the ejector.