Test Group YBMXV02.8LEV
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2000 BMW Z8, 2000 BMW Z3, 2000 BMW X5, 2000 BMW M5, and 2000 BMW M Roadster. However, it is still accessible from the selected car via links, so may be relevant.
- Catalyst Monitoring General Description - Catalyst monitoring is based on monitoring its oxygen storage capability. The engine closed loop feedback control generates lambda (air/fuel ratio) oscillations in the exhaust gas. These oscillations are dampened by the oxygen storage activity of the catalyst. The amplitude of the remaining lambda oscillations downstream of the catalyst indicates the storage capability.
- Monitoring Procedure - In order to determine the catalysts efficiency a fixed number of complete lambda controller cycles (oxygen oscillations from upstream sensor) are used to calculate the areas which are enclosed by the controller cycle curve and is also calculated mean value. See Fig 1. The average of all areas displays the magnitude of oxygen admission to the catalytic converter. The magnitude of oxygen admission is used to calculate the maximum permissible oscillation (areas of the cycle) of the downstream sensor of a still good working catalyst. See Fig 2. Now the original measured oscillation (average of areas) from downstream sensor is compared to the calculated maximum permissible value. See Fig 3. A fault is detected if the quotient (measured to calculated value) is greater than a fixed number.