Abstract: A method for detecting flow-reducing changes in an exhaust-gas catalyst body is provided. The method includes measuring the ion-current signal from an ion-current probe in an internal combustion engine and monitoring the signal to determine whether its signal strength for a particular operating cycle falls below a minimum strength which can be specified as a function of the engine operating state. The method also include providing warning information to the control system when such an event occurs. The method further includes a variety of embodiments used to determine whether the ion current signal falls below a minimum strength.

Abstract: An internal combustion engine with a piston arranged in a cylinder bore, a pair of intake passages to the cylinder bore, and having a piston crown provided with a crescent-shaped depression. The inlet passages are arranged symmetrically with respect to an axis of symmetry running through the center of the cylinder bore between the two intake passages. The crescent-shaped depression formed in the piston crown extends across and is symmetrical with respect to the axis of symmetry.