1.3.2 Statistics, Fault Processing

Emission Limit: 

The DTC for emission relevant misfiring is temporarily stored when the sum of cylinder(s) misfire counters exceeds the limit of four times more than a predetermined value, either within 1000 revolutions during a driving cycle or during the first 1000 revolutions. The MIL is illuminated and a cylinder selective fault or a global fault is stored in the second consecutive driving cycle in which the emission limits are exceeded.

Catalyst Damage: 

When the weighted sum of the cylinder(s) misfire counters exceeds a predetermined value within 200 revolutions, the fault code for catalyst damage relevant misfiring is stored, the cylinder with the highest rate is switched off, and the MIL is illuminated immediately.

If two cylinders are switched off and the misfire rate still exceeds the damage limits, the MIL immediately flashes. When one of the cylinder selective counters exceeds the predetermined threshold, the following actions are taken:

1. The lambda closed loop system is switched to open loop.
2. The cylinder individual fault code is stored for a single cylinder or the global fault code is set for multiple cylinders.
3. Fuel supply of the misfiring cylinder(s) is cut-off (per customer request).
4. No downstream fuel-trim.

All misfire counters are reset after each interval.