Control system for internal combustion engine

A control system for an internal combustion engine that includes an EGR passage connected to an intake passage and an exhaust passage, and is provided with an EGR device for recirculating part of exhaust gases which are exhausted to the exhaust passage, as EGR gas, via the EGR passage to the intake passage, comprising:

• a throttle valve provided on a downstream side of a connecting portion of the intake passage to the EGR passage, for controlling an amount of intake air flowing through the intake passage;
• a bypass passage connected to an upstream side of the connecting portion of the intake passage to the EGR passage, and to a downstream side of the throttle valve in the intake passage;
• an auxiliary intake air amount control valve provided in the bypass passage, for controlling an auxiliary intake air amount which is an amount of fresh air supplied to a combustion chamber of the engine via the bypass passage;
• operation state-detecting means for detecting an operation state of the engine;
• target auxiliary intake air amount-calculating means for calculating a target auxiliary intake air amount which is necessary for avoiding misfiring of the engine, by supplying only the auxiliary intake air amount to the combustion chamber, according to the detected operation state of the engine;
• target intake air amount-calculating means for calculating a target intake air amount which is a target value of an amount of intake air supplied to the combustion chamber, according to the operation state of the engine;
• misfire determination means for determining whether or not the engine misfires;
• and
• control means for executing, when the engine is in the decelerating operation state and it is determined that the engine misfires, misfire avoidance control for controlling the auxiliary intake air amount control valve to be more opened such that the auxiliary intake air amount becomes the calculated target auxiliary intake air amount, and controlling the throttle valve to be more closed such that the amount of intake air supplied to the combustion chamber becomes the calculated target intake air amount.