ABNORMALITY DIAGNOSING DEVICE FOR VARIABLE VALVE DEVICE

摘要

PROBLEM TO BE SOLVED: To accurately diagnose existence of abnormality of a variable intake valve lift device. SOLUTION: An ECU 27 switches a control mode of the variable intake valve lift device 33 between a low speed mode and a high speed mode according to an engine operation condition, and changes ignition timing according to switching of the control mode. Existence of abnormality of the variable intake valve lift device 33 (stuck in the low speed mode) is determined if knocking is detected by a knocking sensor 42 when the control mode is switched from the low speed mode to the high speed mode with consideration that ignition timing exceeds a knocking limit and knocking is generated if stuck at the low speed mode when the control mode is switched from the low speed mode to the high speed mode. Existence of abnormality of the variable intake valve lift device 33 (stuck in the high speed mode) is determined if combustion stability drops lower than a predetermined level during light load operation after switching the control mode from the high speed mode to the low speed mode. COPYRIGHT: (C)2005,JPO&NCIPI