Process for testing the operating efficiency of exhaust gas catalysts

Claim 1

A process for testing an operating efficiency of an exhaust gas catalyst inserted in an exhaust gas train of an internal-combustion engine, the process comprising the steps of: a) operating the internal-combustion engine during a first time period and determining a first operating condition of the internal-combustion engine via one or more parameters of at least one of the internal-combustion engine and the exhaust gas train, which parameters are sensed in an up-to-date manner and which are processed by a control unit, said parameters, during the first time period, meeting specified marginal conditions for a determination of the first operating condition; b) operating the internal-combustion engine during a second time period in the first operating condition if at least one of the sensed parameters corresponds to a specified desired value, or if said at least one of the sensed parameters does not correspond to the specified desired value, then adjusting the internal-combustion engine into a second operating condition by changing a value of at least one of the sensed parameters of the internal-combustion engine and, recognizing the second operating condition by comparing the up-to-date parameter values with specified desired values for the second operating condition; c) acting upon the exhaust gas catalyst with an exhaust gas pulse which does not correspond to the second operating condition existing during the second time period and which produces one of an under or over-stoichiometric engine operation; d) sensing values of at least one first parameter of the exhaust gas train which changes as a result of the exhaust gas pulse; e) forming at least one first parameter difference between a parameter value sensed before or while the exhaust gas catalyst is acted upon by the exhaust gas pulse and its value after the exhaust gas catalyst is acted upon by the exhaust gas pulse, and comparing the first parameter difference with a specified first desired difference range, and continuing the process if the first parameter difference is within the first parameter desired difference range; and f) analyzing a change of the first parameter and triggering a signal indicating an operational inefficiency of the exhaust gas catalyst if the change deviates from a desired change after at least one implementation of the process steps and, storing the operational inefficiency in a fault memory of the control unit.