Patent ID: 6940284
Filing Date: 2005-09-06
Classification: F02D,F02P,G01R

Abstract:
1. A method for diagnosis of ignition system faults in an internal combustion engine of a type that includes an ignition system that includes at least two ignition coils, each of the ignition coils having a primary connector that connects to a cylinder pair, the method comprising the steps of: consecutively disconnecting and reconnecting the primary connector for each coil that connects to a cylinder pair; when a single primary connector is disconnected, determining whether misfiring or roughness declines, thereby identifying a faulty cylinder pair; for each cylinder of the identified faulty cylinder pair, measuring a firing line voltage for each accessible spark plug wire connected to the identified faulty cylinder pair; identifying a faulty cylinder based on a measured abnormal firing line voltage; prior to the step of determining whether the misfiring or roughness declines when the primary connector is disconnected, determining whether idle speed of the vehicle is lower than fast idle speed before one of the primary connectors is disconnected; and if the idle speed is lower than fast idle speed, increasing the idle speed of the vehicle such that the idle speed of the vehicle is at fast idle speed.