Secondary air supply system for internal combustion engine

摘要

A secondary air pipe is connected to an exhaust pipe upstream of a catalyst, and a secondary air pump is connected to an upstream portion of the secondary air pipe. An ECU determines an operating period of the secondary air pump before the secondary air pump is operated in order to drive the secondary air pump within the operating period. Especially, the ECU detects a pump driving load during a secondary air supply to correct the operating period of the secondary air pump based on the detected pump driving load.