Abstract: A method for diagnosing an exhaust-gas recirculation system of an internal combustion engine provides that the fuel quantity, which is needed for a desired mixture composition, is computed, at least approximately, in a control apparatus from at least stored data of the EGR system. The stored data can be in the form of a through-flow characteristic line. Thereafter, the fuel quantity is corrected by a control factor in dependence upon the mixture composition. The control factor is computed and stored when the EGR system is switched on and the control factor is computed and stored when the EGR system is switched off. The difference of these control factors is then formed and compared to pregiven values. A fault signal is outputted in the event of a deviation.

Abstract: The invention is directed to a method for diagnosing an exhaust-gas recirculation system of an internal combustion engine wherein the fuel quantity, which is needed for a desired mixture composition, is computed, at least approximately, in a control apparatus, inter alia, from stored data of the EGR system. The stored data can be in the form of a through-flow characteristic line. Thereafter, the fuel quantity is corrected by a control factor in dependence upon the mixture composition. The control factor is computed and stored when the EGR system is switched on and the control factor is computed and stored when the EGR system is switched off. The difference of these control factors is then formed and compared to pregiven values. A fault signal is outputted in the event of a deviation.

Abstract: A method and an arrangement for idle adjustment of an internal combustion engine provide that the idle rpm is increased when the engine is warm. A warm engine is then present when the oil temperature exceeds a threshold at which the oil pressure can become too low. Exceeding the oil temperature threshold is determined in dependence upon the engine temperature, the intake-air temperature and, if necessary, the engine rpm and the load of the engine.