With a Nissan spark plug wire operating properly and being connected to each cylinder, the smooth operation of your engine is possible. On older Nissan models the spark plug wire was connected to the distributor cap. Today's modern engine has eliminated the distributor and the wires are directly connected to the ignition coil. Not only has the number of components in the ignition system changed over the years, but also the physical makeup of the spark plug wires themselves. The older style of wire made use of the conductivity properties of copper because it has a natural low resistance to an electrical current. This is why it was used in the creation of the wires to help transmit the electrical impulse to the spark plugs. With advancements in the materials that are now being used, the new type of Nissan spark plug wires no longer has a cooper core but instead uses a carbon fiber one. These fibers have an even lower resistance to an electrical current than what copper possesses. This makes it possible for a more consistent flow of voltage to each spark plug than ever before. Both of these types of spark plug wires do last for a considerable amount of time, but will wear out in terms of the resistance to the flow of the electrical charge will increase. When this occurs on your Nissan, they will have to be replaced for the full potential of your engine to be realized. The time frame for the replacement of the spark plug wires for your Nissan engine should occur on every 2 to 3 tune-ups, or 60,000 to 90,000 miles. If you wait until the engine is noticeable running rough, then you have just robbed yourself of fuel mileage and performance.