It is the Nissan ignition coil that provides the electrical impulse to the engine so the air and fuel mixture can be ignited. On the many different Nissan models there are two different types of ignition coils that have been used over the years. On older Nissan models, the ignition coil has a single outlet line. This output is connected to the distributor by means of a single ignition wire. The supply of the electrical current was continuous and it was the distributor that sent the different spark plugs the impulse when it was required for the explosions in the combustion chambers to be set off on time. On the new Nissan models now being produced, the ignition coil is directly connected to each cylinder by an ignition wire. The impulse being sent to each spark plug is no longer being directed by the mechanical movement as it was when the distributor was part of the ignition system. Today with electronic ignition, the onboard computer is the device that regulates the timing of these impulses that are sent to the appropriate spark plug for the combustion of the air/fuel mixture. The appearance of the two types of Nissan ignition coils is also different. The older style only has one wire connected to it while the new one will have a separate wire for each cylinder your engine has. This makes it relatively easy for the type of ignition system on your vehicle to be properly identified. Regardless of the type of ignition system you have on your vehicle, the ignition coil must be producing the correct voltage at the right time for the spark to reach the cylinder on time for the engine to operate.