Measurement Of Oxygen Storage Capacity (OSC)
Next, the engine is operated with a high A/F ratio (>1). The oxygen mass absorbed by the catalyst is calculated using the signal of the upstream lambda sensor as follows
osc(t) = air mass flow * lean mixture (-1) * dt
This lean mixture is requested until
- either the downstream lambda sensor indicates the catalyst to be completely saturated with oxygen, or
- the stored oxygen mass (osc(t)) exceeds the OSC threshold of the borderline catalyst.