MALFUNCTION DETECTION DEVICE FOR IGNITION PLUG OF INTERNAL COMBUSTION ENGINE AND MISFIRE DETECTION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE: To improve misfire judgment precision by providing a plug condition judgment means to judge that an ignition plug is in the state of malfunction in the case where it is discriminated by a discrimination means that a value related to electric resistance of the ignition plug is lower than a specified value. ;CONSTITUTION: An electric source terminal T1 is connected to an ignition coil 1. One end of a secondary side coil 3 is connected to an anode of a diode 7 and a cathode of the diode 7 is connected to an ignition plug 5 through a distributor 6. In the middle of a connection wire 15, an ignition voltage sensor 10 electrostatically connected to the connection wire 15 is provided. Output of the ignition voltage sensor 10 is connected to a misfire judgment circuit 12 of an electronic control unit 8. The misfire judgment circuit 12 is connected to a central processing unit CPU 11, and a judgment result is input to the CPU 11. The CPU 11 carries out timing control related to misfire judgment. Consequently, it is possible to further improve misfire judgment precision.;COPYRIGHT: (C)1993,JPO&Japio