The effect of engine misfire on catalytic converter and vehicle emissions
A conventional automotive emission control system depends on the measurements provided by various sensors to control the air-fuel (A/F) ratio. Maintaining the A/F ratio close to stoichiometry permits catalytic converter to operate in an optimized efficiency, which reduces the exhaust emission. Malfunction resulted from engine misfire makes catalyst''s converting efficiency drop. Such a condition results in increased emissions as well as in damage to catalytic converters. So current researches are proceeded in response to the California OBD II (On-Board Diagnostics) and EOBD that will be adopted in Europe requirements for engine misfire detection in passenger vehicles. In this study, two methods to diagnose the misfire an approached: catalytic converter''s temperature measurement over the threshold exposure temperature to examine the catalyst''s damage, and the vehicle emission test over FTP-75 cycle by varying misfire rates.