Cold Start Emission Reduction Strategy Monitoring

Catalyst heating function is used to reduce cold start emission. Combination of increased engine speed and air mass flow rate (MAF) and also spark timing retardation results in faster exhaust gas temperature increase. It can be realized by opening more idle speed actuator during catalyst heating phase.

If lower air path restriction happens, engine torque is slightly decreased due to low MAF. A low MAF is compensated by spark advance increase to keep constant engine torque. But engine speed deviation does not happen in this time.

If higher air path restriction happens, even though spark timing compensates, engine speed cannot meet the target engine speed due to very low MAF. Therefore, key control parameter for catalyst heating function is air path. Air path is represented as MAF deviation in EMS control parameter.