Abstract: An engine system comprising of at least one fuel injector sensor coupled to at least one fuel injector of a first group of cylinders; at least one fuel injector sensor coupled to at least one fuel injector of a second group of cylinders; and a controller configured to operate the engine system in at least a first mode and a second mode, where in the first mode the first and second cylinder groups combust air and injected fuel, where in the second mode at least one of the first and second cylinder groups combusts air and injected fuel and the other one of the first and second cylinder groups pumps air without injecting fuel; where in the first mode the controller sets a degradation condition responsive to detection of inactivity of the at least one fuel injector by the at least one fuel injection sensors; and where in the second mode the controller sets a degradation condition responsive to at least one of detection of fuel injection activity in both the first and second groups of cylinders by the fuel injecti

Abstract: A method for rapidly heating an emission control device in an engine exhaust uses excess air added to the exhaust via an air introduction device. After an engine cold start, the engine is operated to raise exhaust manifold temperature to a first predetermined value by operating the engine with a lean air-fuel ratio and retarded ignition timing. Once the exhaust manifold reaches the predetermined temperature value, the engine is switched to operate rich and air is added via the air introduction device. The added air and rich exhaust gas burn in the exhaust, thereby generating heat and raising catalyst temperature even more rapidly. The rich operation and excess air are continued until either engine airflow increases beyond a pre-selected value, or the emission control device reaches a desired temperature value. After the emission control device reaches the desired temperature, the engine is operated substantially around stoichiometry.