METHOD FOR DIAGNOSING CYLINDER-BASED INDIVIDUAL CATALYSTS OF A MULTI-CYLINDER SPARK IGNITED INTERNAL COMBUSTION ENGINE

摘要

The invention relates to a method which is characterized in that before an active catalyst diagnosis is carried out the mixture is dynamically trimmed for all individual catalysts (K1 - K4) using a signal of a lambda sensor (LS1) common to the individual catalysts. Once the mixture is successfully trimmed, the cylinder-based forced activation is adjusted in such a manner that the individual catalysts (K1 - K4), by virtue of the charge imprinted thereon for a threshold catalyst, exceed their remaining oxygen storage capacity to such an extent that the lambda sensor (LS1) is enabled to measure the storable charge. The cylinder-based lambda signals reconstructed from the sensor signal are then used to determine specific diagnostic values for every individual catalyst (K1 - K4).