Patent ID: 6094974
Filing Date: 2000-08-01
Classification: F01L

Abstract:
A self-diagnosing apparatus of a variable valve timing structure for changing the opening/closing timing of an intake valve and/or an exhaust valve by changing a rotation phase of a cam shaft corresponding to a target value, said apparatus comprising:a rotation phase detection means for detecting the rotation phase of said cam shaft;a response diagnosing means for judging an abnormality in response characteristic of said variable timing structure when, at the point of time where a predetermined time has passed after said target value has step-changed, a deviation between the target value after step-changed and the rotation phase detected by said rotation phase detection means is equal to or above a threshold value, and outputting a signal indicating abnormality of the response characteristic; anda diagnosis time setting means for setting said predetermined time to be longer as the step-change quantity of said target value is larger.