Method and system for catalyst temperature control

A method for an engine, comprising:

• during an engine cold-start,
• restarting an engine with each of a post-catalyst exhaust throttle and an EGR valve closed;
• with the valves closed, diverting at least a portion of throttled exhaust gas around the exhaust throttle via an EGR cooler and an ejector;
• and
• maintaining each of the throttle and the valve closed until an EGR cooler outlet temperature is above a threshold.

An engine system, comprising:

• an engine including an intake and an exhaust;
• a turbocharger including an intake compressor and an exhaust turbine
• an exhaust catalyst;
• a post-catalyst exhaust throttle;
• an EGR system including an EGR passage, an EGR cooler and an EGR valve, the system fluidly coupling the engine exhaust downstream of the catalyst and upstream of the throttle, to the engine intake, upstream of the compressor;
• a branch passage including an ejector fluidly coupling an outlet of the EGR cooler to the engine exhaust, downstream of the throttle;
• and
• a controller with computer readable instructions for,
• operating the system in a first mode with each of the throttle and the EGR valve closed and while flowing exhaust gas from the catalyst, through the EGR cooler and then through the ejector;
• operating the system in a second mode with each of the throttle and the EGR valve open and while flowing exhaust gas from the catalyst, through the ejector and then through the ejector;
• and
• during both the first and second mode, drawing vacuum at the ejector.