2003 3BMXV03.0LER, 3BMXV03.0M5R & 3BMXT03.0E5R
WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 2003 BMW Z8, 2003 BMW Z4, 2003 BMW X5, 2003 BMW M5, and 2003 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.
- General Description - Catalyst monitoring is based on monitoring its oxygen storage capability. Engine closed loop feedback control generates lambda (air/fuel ratio) oscillations in exhaust gas. These oscillations are dampened by oxygen storage activity of catalyst. Amplitude of remaining lambda oscillations downstream of catalyst indicates storage capability. See Fig 1-Fig 2 .
- Monitoring Procedure - To determine catalyst efficiency, a fixed number of complete lambda controller cycles (oxygen oscillation from upstream sensor) are used to calculate areas which are enclosed by controller cycle curve and is also calculated mean value. Average of all areas displays magnitude of oxygen admission to catalytic converter.