METHOD AND DEVICE FOR INSPECTING SPARK PLUG FOR ENGINE

PROBLEM TO BE SOLVED: To improve determination accuracy and reliability in a method for inspecting a spark plug for an engine. SOLUTION: Controlled current is supplied to a power transistor 5 by an electric discharge control part 11 of a controller 6, secondary voltage is induced at a secondary coil side by interrupting primary current at a primary coil 4 side of an ignition coil 2 to discharge electricity at the spark plug 9 built in an engine main body 8. Primary voltage is monitored by a determination part 6 of the controller 6, discharge time is measured based on primary voltage, and quality of discharge gap of the spark plug 9 is determined based on the discharge time. Internal resistance of the spark plug 9 is operated based on an inclination of voltage drop of the primary voltage during discharge, and discharge time is corrected based on the internal resistance. Consequently, if internal resistances of the spark plugs 9 vary, accuracy and reliability of inspection can be improved with elimination influence of the variation. COPYRIGHT: (C)2009,JPO&INPIT