US Patent 9238983 Secondary air introduction system

Embodiments for heating an emission control device are provided. In one example, a method for a turbocharged engine comprises during an engine cold-start, delivering boosted air from downstream of a compressor into a wastegate duct coupled across a turbine and exothermically reacting a reductant with the boosted air upstream of an exhaust emission control device. In this way, boosted air may be used to initiate an exothermic reaction to heat the device.