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In modern systems, the distributor is omitted and ignition is controlled electronically, instead. Much smaller coils are used with one coil for each spark plug or one coil serving two spark plugs (so two coils in a four-cylinder car). These coils may be remote-mounted or they may be placed on top of the spark plug (coil-on-plug or direct injection). Where one coil serves two spark plugs (in two cylinders), it is through the "wasted spark" system. In this arrangement, the coil generates two sparks per cycle to both the cylinders. The fuel in the cylinder that is nearing the end of its compression stroke is ignited, whereas, the spark in its companion nearing the end of its exhaust stroke has no effect. The wasted spark system is more reliable than a single coil system with a distributor and cheaper than coil-on-plug. Where the coils are remote mounted, they may all be contained in a single molded block with multiple high-tension terminals. This is commonly called a coil-pack. Your Volvo ignition coils are part of a larger system, which is the ignition system. The ignition system is part of an even larger engine system. The ignition system's primary responsibility is the timely burning of the fuel-air mixture in the engine. Your Volvo user's manual would carry the recommended service interval for your ignition system, including your Volvo ignition coil. Your Volvo engine might run rough, buck, surge, stall or even get poor fuel economy. These are signs that your ignition system might need servicing as they are potentially an ignition system problem. When this happens, drive to the nearest Volvo dealership and have a qualified technician take a look around. Your Volvo engine might be in problem in the long run.
John Garett |
