| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the diagnosis precision of an inter-cylinder imbalance abnormality diagnosis of the engine. <P>SOLUTION: When an inter-cylinder imbalance abnormality diagnosis is performed during an operation of an EGR device 35, a part influenced by an EGR gas is calculated by a map or the like on the basis of a degree of opening or the like of an EGR control valve 34, an abnormality decision threshold is corrected in accordance with a part influenced by the EGR gas, and thereby, such erroneous decision as to assume that there is no inter-cylinder imbalance abnormality (normality) caused by an influence of the EGR gas is prevented. Furthermore, when the inter-cylinder imbalance abnormality diagnosis is performed during the operation of the EGR device 35 and such decision as to assume that there is an inter-cylinder imbalance abnormality is performed such a possibility of erroneous decision as to assume that there is an inter-cylinder imbalance abnormality caused by an influence of the EGR gas is determined and, when it is decided that the remaining amount of the EGR gas in an intake system reaches a prescribed value or smaller in such a state as to inhibit or limit an operation of an EGR device 32, the inter-cylinder imbalance abnormality diagnosis is again performed, and thereby, the presence or absence of the inter-cylinder imbalance abnormality is precisely decided without being affected by the ECR gas. <P>COPYRIGHT: (C)2012,JPO&INPIT |
