To avoid misfiring, a certain tension-level, which lies way above the normal need, is necessary. Since the tension continually increases, until the space between the center- and the earth electrode(s) is ionosed. If the ignition system is not able to reach this level of tension or a path to earth is found before reaching the respective electrode(s), then no ignition of the mixture will take place in this particular cylinder.
The results of frequent misfiring are disastrous, apart from a higher consumption and lower performance, damage to the catalytic converter can not be ruled out. Thereby, through the burning of the mixture in this component, regardless of whether it's made of ceramic or metal, a substance is formed which can clog the entire exhaust gas system. Fortunately, modern engine-management can recognize such undesirable developments and at least stop the injection to this particular cylinder.
Thus, additional kilo-volts and a reliable insulation are absolutely necessary. You may be able to imagine, that during the ionisation phase, there is no constant current flow. First of all, a high amount of energy is needed to make the penetrating mixture conductive. There are any number of factors which complicate this procedure: a lean mixture, the coating on the electrodes, high pressure and perhaps even too much swirling. The shape of the electrodes involved also plays a role. Sharp edges are more likely to promote an effective arcing.
Coating and burning down of the edges are of course, a part of the ageing proccess of the spark plugs. This can be initiated partly, by the availability of a higher ignition voltage. However, one thing is certain, problems are more likely to occur, if the reserves are used up through other adverse circumstances, e.g., cold starting in winter.
There are actually two methods if one is seriously thinking about checking such equipment. The basic functions can be checked by using the quite simple, conventional multimeter or even using just a testing lamp. This would be interresting if, e.g., the engine doesn't do anything except turn over at starting speed. The 12V plus (terminal 15) and the several minus signals (terminal 1) for the respective ignition to be triggered, must arrive at both the single- as well as the twin-spark coil.
If plus is there and tacts a lamp connected to terminal 15 and terminal 1 regularly, then the signals coming from the control device are probably ok. In this case, we assume that the signals occur at the correct time. It can still turn out, that this is not the case through absolutely inadequate signals. After replacing the coil and/or the spark pugs, it's quite possible that the problem will be solved, however, it has not been analysed and thus, one cannot be certain that it won't occur again.
There are hardly any faults which are so nasty as those that only occur sporadically and are not picked up by the error memory at all or wrongly interpreted. If one takes the car to a garage, then the engine purrs like a satisfied cat. Some effective countermeasures are: you can take the tester with you on a test drive, as a laptop, or you have testing surroundings at your disposal which can supply the suitable control and which can also display difficult situations when the components are still built in. 05/12