<P> In older vehicles, a single coil would serve all the spark plugs via the ignition distributor . Notable exceptions are the Saab 92, some Volkswagens, and the Wartburg 353 which have one ignition coil per cylinder . The flat twin cylinder 1948 Citroën 2CV used one double ended coil without a distributor, and just contact breakers, in a wasted spark system . </P> <P> In modern systems, the distributor is omitted and ignition is instead electronically controlled . Much smaller coils are used with one coil for each spark plug or one coil serving two spark plugs (for example two coils in a four - cylinder engine, or three coils in a six - cylinder engine). A large ignition coil puts out about 40 kV, and a small one such as from a lawn mower puts out about 15 kV . These coils may be remotely mounted or they may be placed on top of the spark plug (coil - on - plug or Direct Ignition). 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 cylinders . The fuel in the cylinder that is nearing the end of its compression stroke is ignited, whereas the spark in its companion that is 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 less expensive than coil - on - plug . </P> <P> Where coils are individually applied per cylinder, they may all be contained in a single molded block with multiple high - tension terminals . This is commonly called a coil - pack . </P> <P> A bad coil pack may cause a misfire, bad fuel consumption or loss of power . </P>

Is ignition coil and coil pack the same thing