Onboard diagnostic system of vehicle ignition system

摘要

A method of operating an onboard diagnostic system for a distributorless ignition system of an internal combustion engine includes detecting the time of occurrence of a spark plug firing and calculating the time of spark plug firing. The calculated time and the detected time are compared to see if they come within a predetermined time period, adjusted for averaged rotational velocity. A fault is indicated if the time of occurrence of the calculated and the detected spark do not come within the predetermined time period.