| 摘要 |
PROBLEM TO BE SOLVED: To provide a control system for an internal combustion engine by which the exhaust amount of NOx in an exhaust gas can be reduced as much as possible when the lean burn is controlled, regardless of the uneven quantity production of the internal combustion engine. SOLUTION: An ignition time advance angle correction amount is retarded (S2) by an amount obtained by subtracting a predetermined width DKLARTDM from the former value of retard ratio KLADVRTD for retarding an ignition time advance angle correction valueθIGADV during the time when a lean burn correction coefficient KLSAF is agreed with a lean burn correction coefficient limit value KLSAFLMT, and theθIGADV is calculated (S5) after the limit process is performed under a condition that the retard ratio is kept within a predetermined range (S4). On the other hand, the ignition time advance angle correction amount is advanced (S3) by the amount obtained by adding the predetermined width DKLARTDP to the former retard ratio, during the time when KLASF is different form the lean burn correction coeffieicnt limit value, and then a step S4 is performed. On condition thatθIGADVMAP is a map value of the ignition time advance angle correction amount map, and KLADV is a correction coefficient decided corresponding to the target air-fuel ratio.
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