Test Groups 1BMXT03.0E5R, 1BMXT03.0E53, 1BMXV02.5M54, 1BMXV03.0LEV, 1BMXV03.0LER, 1BMXV03.0M54 & 1BMXV03.0M5R
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- Catalyst Monitoring Based On Monitoring 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 indicate storage capability.
- 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 display magnitude of oxygen admission to catalytic converter. See Fig 1. Magnitude of oxygen admission is used to calculate maximum permissible oscillation (areas of the cycle) of downstream sensor of a still good working catalyst. Then original measured oscillation (average of areas) from downstream sensor is compared to calculated maximum permissible value. A fault is detected if quotient (measured to calculated value) is greater than a fixed number. See Fig 2.