An ignition apparatus includes an ignition plug, a boost transformer, an ignition power source and a measurement unit. The ignition plug has a center electrode and a ground electrode. The boost transformer supplies the ignition plug with electric power generated in a secondary coil upon supply of AC power from the ignition power source to a primary coil. The measurement unit measures the discharge voltage of the ignition plug. The ignition power source includes a discharge state determining unit that determines the discharge state of the ignition plug based on the measured discharge voltage and a current controlling unit that controls electric current supplied to the primary coil. When a discharge path formed between the center and ground electrodes of the ignition plug is determined by the discharge state determining unit as being in an over-extended state, the current controlling unit reduces the electric current supplied to the primary coil.

An induction cleaning analyzing system includes a pressure sensor, an ignition event detector, and a control module. The pressure sensor measures airflow pressures of intake air and/or exhaust from cylinders in a common airflow pathway of a vehicle. The ignition event detector determines ignition events of the cylinders. The control module obtains pressure waveforms representative of the airflow pressures and divides the pressure waveforms into waveform segments. The control module associates different subsets of the waveform segments with different ones of the cylinders using the ignition events. The control module also identifies cyclic variations in the airflow pressures flowing in the common airflow pathway and caused by at least one of the cylinders by examining the waveform segments associated with the at least one of the cylinders.

An induction cleaning analyzing system includes a pressure sensor, an ignition event detector, and a control module. The pressure sensor measures airflow pressures of intake air and/or exhaust from cylinders in a common airflow pathway of a vehicle. The ignition event detector determines ignition events of the cylinders. The control module obtains pressure waveforms representative of the airflow pressures and divides the pressure waveforms into waveform segments. The control module associates different subsets of the waveform segments with different ones of the cylinders using the ignition events. The control module also identifies cyclic variations in the airflow pressures flowing in the common airflow pathway and caused by at least one of the cylinders by examining the waveform segments associated with the at least one of the cylinders.

A combustion speed, for example, is estimated or evaluated, with a required accuracy, more simply than the conventional art, while reducing man-hours to produce a heat generation rate waveform of an internal combustion engine. An increase rate of a heat generation rate relative to a change in a crank angle in a heat generation rate increasing period (e.g., a first-half combustion period a) in which the heat generation rate increases after ignition of an air-fuel mixture is defined as a heat generation rate gradient b/a that is one of characteristic values of the heat generation rate waveform. The heat generation rate gradient is estimated based on a fuel density (e.g., fuel density .sub.fuel@dQpeak at heat generation rate maximum time) at a predetermined time set in advance in the heat generation rate increasing period so as to produce the heat generation rate waveform using the estimated heat generation rate gradient.

Methods and systems are provided for reducing late burn induced cylinder pre-ignition events. Forced entry of residuals from a late burning cylinder into a neighboring cylinder may be detected based on engine block vibrations sensed in a window during an open exhaust valve of the late burning cylinder. In response to the entry of residuals, a pre-ignition mitigating action, such as fuel enrichment or deactivation, is performed in the neighboring cylinder.

Methods and systems are provided for reducing late burn induced cylinder pre-ignition events. Forced entry of residuals from a late burning cylinder into a neighboring cylinder may be detected based on engine block vibrations sensed in a window during an open exhaust valve of the late burning cylinder. In response to the entry of residuals, a pre-ignition mitigating action, such as fuel enrichment or deactivation, is performed in the neighboring cylinder.

A vehicle ignition system detection device is cooperated with a diagnostic unit and includes a detection unit. The detection unit includes multiple ignition system output holes and multiple detection cables. Each of the detection cables has a plug end and a patch end. Each of the plug ends is inserted in the ignition system output hole corresponding thereto, and each of the patch ends is connected to the coil corresponding thereto. The electro-magnetic detection signals between the patch ends and the coils are sent to the display screen of the diagnostic unit so that the maintainers are acknowledged the conditions of the ignition system.

A vehicle ignition system detection device is cooperated with a diagnostic unit and includes a detection unit. The detection unit includes multiple ignition system output holes and multiple detection cables. Each of the detection cables has a plug end and a patch end. Each of the plug ends is inserted in the ignition system output hole corresponding thereto, and each of the patch ends is connected to the coil corresponding thereto. The electro-magnetic detection signals between the patch ends and the coils are sent to the display screen of the diagnostic unit so that the maintainers are acknowledged the conditions of the ignition system.

A detection device for vehicle ignition system includes a body with a first IC circuit board received therein which is electrically connected with a power source. A probe connected to the body and is electrically connected to a ground line and the first IC circuit board. The body has a connection hole, a power switch for activating the detection device, an activation switch, a first display unit and a second display unit. The ground line is connected with a metal part of a vehicle to form a loop. When the probe contacts the coil, the ignition voltage signal of the coil is detected and displayed on the first display unit, and the combustion time signal of the coil is detected and displayed on the second unit. By the two signals, the maintainers are acknowledged the operation condition of the ignition system of the vehicle.