Misfire Diagnostic For Flex Vehicles - A Case Study

The exigency of misfire diagnosis is an important part of the OBDBr-2 Normative Instruction that will be valid from January, 1^st 2010. OBD means an on-board diagnostic system for emission control which must have the capability if identifying the likely area of malfunction by means of fault codes stored in computer memory. The Normative Instruction requires that the OBDBr-2 system must detect engine misfire and indicates the vehicle driver, through the MIL (Malfunction Indicator Light), when the misfire ratio causes emissions above the established limits (NMHC = 0,30 g/km, CO = 4,11 g/km e NOx = 0,75 g/km).Besides, the misfire diagnosis must be active during all vehicle useful life, since its manufacturing and under the most operational conditions.