That someplace takes the spark and sends it out to the spark plugs, and that someplace is the distributor. The distributor is basically a very precise spinner. As it spins, it distributes the sparks to the individual spark plugs at exactly the right time.
It distributes the sparks by taking the powerful spark that came in via the coil wire and sending it through a spinning electrical contact known as the rotor. The rotor spins because it's connected directly to the shaft of the distributor.
As the rotor spins, it makes contact with a number of points 4, 6, 8 or 12 depending on how many cylinders your engine has and sends the spark through that point to the plug wire on the other end.
Modern distributors have electronic assistance that can do things like alter the ignition timing. After the coil takes the weaker juice and makes a high powered spark and the distributor takes the powerful spark and spins it to the right outlet, we need a way to take the spark to the spark plug.
This is done through the spark plug wires. Each contact point on the distributor cap is connected to a plug wire that takes the spark to the spark plug. The spark plugs are screwed into the cylinder head, which means that the end of the plug is sitting at the top of the cylinder where the action happens. At just the right time thanks to the distributor , when the intake valves have let the right amount of fuel vapor and air into the cylinder, the spark plug makes a nice, blue, hot spark that ignites the mixture and creates combustion.
At this point, the ignition system has done its job, a job it can do thousands of times per minute. In the old days, a distributor relied on a lot of its own "mechanical intuition" to keep the spark timed perfectly.
It did this through a setup called a points-and-condenser system. Ignition points were set to a specific gap that created an optimal spark while the condenser regulated. These days this is all handled by computers. The computer that directly regulates your ignition system is called the ignition module, or ignition control module. There is no maintenance or repair procedure for the module aside from replacement. Actively scan device characteristics for identification.
The ignition system on your car has to work in perfect concert with the rest of the engine. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.
This transformation causes the pressure in the cylinder to increase dramatically and forces the piston down. In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke.
Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.
To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke , so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful work. And because the length of the stroke and the area of the piston are fixed, the only way to maximize work is by increasing pressure.
The timing of the spark is important, and the timing can either be advanced or retarded depending on conditions. The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance : The faster the engine speed, the more advance is required.
Other goals, like minimizing emissions , take priority when maximum power is not required. For instance, by retarding the spark timing moving the spark closer to the top of the compression stroke , maximum cylinder pressures and temperatures can be reduced. Lowering temperatures helps reduce the formation of nitrogen oxides NO x , which are a regulated pollutant. Retarding the timing may also eliminate knocking; some cars that have knock sensors will do this automatically. The electricity must be at a very high voltage in order to travel across the gap and create a good spark.
Voltage at the spark plug can be anywhere from 40, to , volts. The spark plug must have an insulated passageway for this high voltage to travel down to the electrode, where it can jump the gap and, from there, be conducted into the engine block and grounded.
The plug also has to withstand the extreme heat and pressure inside the cylinder, and must be designed so that deposits from fuel additives do not build up on the plug. Spark plugs use a ceramic insert to isolate the high voltage at the electrode, ensuring that the spark happens at the tip of the electrode and not anywhere else on the plug; this insert does double-duty by helping to burn off deposits.
Ceramic is a fairly poor heat conductor, so the material gets quite hot during operation. This heat helps to burn off deposits from the electrode. Some cars require a hot plug. This type of plug is designed with a ceramic insert that has a smaller contact area with the metal part of the plug.
This reduces the heat transfer from the ceramic, making it run hotter and thus burn away more deposits. Cold plugs are designed with more contact area, so they run cooler. The carmaker will select the right temperature plug for each car. Some cars with high-performance engines naturally generate more heat, so they need colder plugs. If the spark plug gets too hot, it could ignite the fuel before the spark fires; so it is important to stick with the right type of plug for your car.
Next, we'll learn about the coil that generates the high voltages required to create a spark. The coil is a simple device -- essentially a high-voltage transformer made up of two coils of wire.
One coil of wire is called the primary coil. Wrapped around it is the secondary coil. The secondary coil normally has hundreds of times more turns of wire than the primary coil. The primary coil's current can be suddenly disrupted by the breaker points , or by a solid-state device in an electronic ignition.
The ignition system is made up of the following main components: Battery, ignition switch, coil, contact points, condenser, distributor, sparking plugs and cables. The main components which are obviously associated with the ignition system are shown below. There are three basic types of automotive ignition systems: distributor-based, distributor-less, and coil-on-plug COP.
Early ignition systems used fully mechanical distributors to deliver the spark at the right time. Next came more reliable distributors equipped with solid-state switches and ignition control modules. An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers, rocket engines, etc.
They usually have glowplugs that preheat the combustion chamber to allow starting in cold weather. Ignition systems have two circuits that result in a spark being fired at the end of a spark plug. The primary circuit is between the battery and the ignition coil. The secondary circuit is between the ignition coil and the spark plug.
Ignition scope patterns are divided into three basic sections-firing, intermediate and dwell Fig. The secondary high-voltage pattern shows the condition of the coil, the coil lead to the distributor, the distributor cap and rotor, the spark plug leads and the plugs.
Electronic triggering devices send a signal current to the ignition module, which then breaks the primary circuit. Currently, there are four types of ignition systems used in most cars and trucks, by order of invention: conventional breaker-point mechanical ignitions, high energy electronic ignitions, distributor-less waste spark ignition and coil-on-plug ignitions.
The ignition coil acts like a transformer. By means of two coils, one inside the other, the ignition coil transforms the electrical energy from the vehicle battery into high voltage, saves it briefly and then emits it as a high voltage current pulse to the spark plug.
The battery provides low voltage electricity to the ignition coil. The ignition coil converts the low voltage electricity into high voltage power in timed pulses.
The power travels down the spark plug wires to the spark plugs and causes sparks. The sparks ignite the fuel and air in the engine cylinders. That causes a magnetic field to form in the ignition coil.
If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30, volts! The high voltage is carried away from the coil by a high-tension cable that looks like a short piece of spark plug cable and runs to the distributor tower.
One of the most common symptoms associated with a faulty ignition coil is engine performance issues. Faulty coils may cause the vehicle to experience misfires, a rough idle, a loss in power and acceleration, and a reduction in gas mileage.
In some cases the performance issues may even result in the vehicle stalling. Most coils should read between 0. Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil.
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