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1.3.2 Statistics, fault processing

Emission Limit: 

If the sum of cylinder(s) misfire counters within 1000 revolutions is 4 times exceeding a predetermined value during a driving cycle, or during the first 1000 revolutions, the fault code for emission relevant misfiring is temporary stored. If the following driving cycle is also above the emission limits, the MIL will be switched on and a cylinder selective or global fault will be stored.

Catalyst Damage: 

If the weighted sum of cylinder(s) misfire counters within 200 revolutions is exceeding a predetermined value the fault code for catalyst damage relevant misfiring is stored and the cylinder with the highest rate will be switched off and the MIL will be switched on immediately. If two cylinders are switched off and the misfire rate is still above the damage limits, MIL is flashed immediately. If one of the cylinder selective counters is exceeding the predetermined threshold the following measures take place:

  1. The lambda closed loop system is switched to open-loop condition.
  2. The cylinder individual fault code is stored or if multiple cylinders, then the global fault code is set.
  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.

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