A distributor is a component of an engine ignition system on some vehicles.
In order for your engine to run, a mixture of air and fuel are introduced into the cylinders, compressed by the pistons, and ignited by the spark plugs. The rapidly-expanding gasses that result from combustion force the pistons downward in their cylinders. The pistons, in turn, rotate the crankshaft in the same way that you might pedal a bicycle. But these operations do not happen all at once. Each spark plug must fire at a specific time in succession so that the pistons move at just the right time.
On older engines, the distributor is used to “distribute” electrical current to the spark plugs. It uses a rotating shaft with a housing on top (the distributor cap) to which the spark plug wires and coil wire are attached. The distributor shaft spins in response to the engine crankshaft. At the top of the shaft, a plastic rotor spins inside the distributor cap. Electrical contacts on the rotor pass along a high voltage current from the coil to other contacts placed around the inside of the distributor cap. Those contacts are connected to the spark plug wires.
Two types of distributors have been used - mechanical and electronic - the former being the older of the two. Today, however, many vehicle manufacturers have shifted to distributorless ignitions, where individual coils (the components that convert the electricity from low voltage to high voltage) are placed on top of each spark plug. These “coil-on-plug” devices are controlled by signals from the vehicle’s computer, allowing for a more precise operation of the spark plugs.
More than likely, your vehicle does not have a distributor. If it does, it most likely features an electronic distributor, which is more reliable than older mechanical distributors. And if it does, regardless which type of distributor it has, if there is a problem with the device, it will show up in the performance of your engine. That is because the distributor is directly responsible for controlling the high voltage electric current that goes to the spark plugs at just the right time. And that has a direct impact on combustion and the function of an engine.
If the distributor is malfunctioning, you might notice one or more of the following signs:
Service to a distributor comes in two categories - replacement of the components that tend to wear out (the cap, rotor, and possibly the condenser) or replacement of the entire device. If the whole distributor assembly needs to be replaced, a technician will take the following general steps, depending on the type of distributor used: