The BMW distributor cap is a crucial ignition system component that is designed to aid in the process that brings the high voltage spark to the engine, which is necessary to the combustion process. The distributor is connected to the coil with an insulated high voltage wire. The distributor receives voltage from the coil through this connection, which must be transmitted to each engine cylinder to ignite the fuel and begin the combustion process. The BMW distributor cap and rotor are the components that transmit that power. The rotor is attached to the center shaft of the distributor, inside the BMW distributor cap. The rotor spins inside the BMW distributor cap with it tip passing a series of contacts on the way around. There is one contact for every engine cylinder and as the tip of the rotor spins past each one, the coil sends a burst of high voltage to arc across from the rotor to the contact. This voltage is then transmitted through the ignition wires to the spark plugs to cause the ignition of the fuel in the engine cylinder. Gradually, this transmission of spark will damage the BMW distributor cap, causing carbon tracking that will begin to interfere with the efficient transmission of voltage through the system. For this reason, the BMW distributor cap must be replaced regularly, usually as a part of the regular vehicle tune-up. We carry a selection of quality BMW distributor cap replacements in our user-friendly online catalog. Our secure site will make ordering safe and easy or if you prefer to order by phone, our toll-free phone line can take your BMW distributor cap order just as conveniently.