(Updated on February 19, 2021)
When an engine starts running, it produces a great deal of voltage which enters the ignition coils. For older vehicles that have traditional distributors (not modern day ignition systems), this electricity is sent into an electrode of the distributor rotor.
This causes the rotor to rotate and transfer electrical power to separate electrodes which are positioned inside the distributor cap.
From there, the distributor cap transfers electricity to the spark plugs through a series of spark plug wires. This entire process happens each time the cylinders of the engine demand a spark to ignite the air and fuel mixture inside of them for combustion.
As you can see, the distributor cap and rotor are very important parts of the internal combustion process for older vehicles. You cannot afford to have a vehicle with a faulty distributor cap and rotor. If you do, you can expect a lot of problems with the overall functionality of your vehicle.
Signs of a Faulty Distributor Cap and Rotor
You will certainly recognize the symptoms of a bad distributor cap and rotor as they arise. Do not ignore these symptoms for too long or else you may find yourself stranded somewhere because your car won’t move. The only solution is to replace the distributor cap as soon as possible.
Below are the top 5 symptoms of a bad distributor cap and rotor.
1) Cannot Start Vehicle
You need a functional distributor cap and rotor to start the car. Without that electrical spark in the combustion chamber, the engine won’t start running.
You may only have difficulty starting your vehicle at first, but then it will get to a point where you cannot start the vehicle at all.
See Also: What Does a Bad Starter Sound Like?
2) Engine Noises
If you start hearing high pitched squealing sounds (different from a loose serpentine belt) after you start your car, then you may have a dirty distributor cap to the the point that it’s caked with grease and other build up.
If you hear a sputtering, tapping, or clicking noise, then it is either your cap or rotor that has gone bad. Don’t tolerate these noises for any longer than necessary.
3) Check Engine Light
Since a bad distributor cap and rotor affect the internal combustion process of the engine, you can definitely expect the Check Engine warning light to come on. The engine control unit can detect whenever there is improper combustion in the cylinders.
As soon as this is dedicated, the Check Engine light will turn on in your instrument cluster. The warning light alone won’t be enough to indicate that you have a bad distributor cap and rotor.
The problem is that if your vehicle has a distributor cap, there’s a good chance it was made prior to 1996 when the OBD2 protocol arrived so it’s not a simple matter of scanning for codes using your code reader.
Intense shaking may occur in your vehicle when you start it up or change gears. This shaking is a sign that you have engine problems for some reason. You’ll feel the vibrations through the seats because they’re so intense.
This is normally one of the signs of your distributor cap going bad but can signify other problems as well.
5) Engine Stalling
A faulty distributor cap can cause your engine to stall. Voltage must be produced by the spinning distributor rotor for the engine to keep running.
If the rotor does not rotate properly, the engine loses power and stalls out as you’re trying to drive. The longer you let this go on, the worse it will get.
Distributor Cap and Rotor Replacement Cost
When you need to replace your distributor cap and rotor because they have gone bad, you can expect to pay anywhere from $70 to $130 for the job. This total includes both parts and labor costs together.
In most cases, expect to pay somewhere between $30 and $60 for parts and another $40 to $70 in labor. As you can see, this isn’t too expensive of a job compared to others. But be prepared to pay some extra fees and taxes on top of the total estimated price.
Can I Replace the Distributor Cap and Rotor Myself?
For most people, this is a simple task and you’ll save yourself some money by doing so. Back when auto shop class was a thing in high schools, replacing a distributor cap was one of the first things you were taught. But since modern ignition systems are now distributor-less, the task has become a lost art.
Nonetheless, a good service manual will walk you through the process and you may even be able to find a YouTube video for the specific procedure to your vehicle. Just be sure to disconnect the car’s battery to avoid the possibility of zapping yourself.
Get the Best Priced Distributor Rotor Parts
Distributor Rotor Information
The AC Delco Distributor Rotor is key in maintaining optimum performance and to getting the most power out of your vehicle's engine.
When you decide to get an AC Delco distributor rotor, repairing your cherished vehicle with the best parts is the best investment in the long run. By allowing your injectors to use fuel more completely, performance equipment options raise power while cutting excess gasoline usage. Your vehicle is an investment because it has excellent performance and great style, and to keep it going in top condition you need the acme in quality parts and accessories. A vehicle's performance is the culmination of several factors including high quality parts. The car or truck's distributor rotor is a straightforward device that can easily be replaced by simply snapping or bolting it into place. A vehicle's distributor rotor is a part that is intended to deliver an electrical charge to the spark plugs at the precise moment when it is needed. A well-maintained distributor rotor is critical in maintaining optimum performance and to getting the most out of your engine. Your automobile's distributor rotor is installed on the inside of a part called the distributor cap and is joined to cables that transmit electricity to the spark plugs. An old distributor rotor may very well cause a decrease in your car's efficiency or even prevent the vehicle from starting. The parts you need for any automotive job, like an AC Delco distributor rotor, are just a mouse click away when you order from PartsGeek.com.
A fully functioning Beck Arnley Distributor Rotor is critical in maintaining maximum performance and to getting the most power out of your car's engine.
Swing by PartsGeek any time you need the best quality auto and truck parts like the Beck Arnley distributor rotor. By enabling your injectors to burn fuel more completely, performance components increase power while lowering excess fuel wastage. If you selected that high-performance car or truck for its high-end engine power and performance, back up that investment and buy high quality aftermarket parts and accessories. It doesn't matter if you race your car or just enjoy driving a performance vehicle, top quality auto parts are essential. A faulty distributor rotor may cause a reduction in your car or truck's efficiency or might even prevent the vehicle from running at all. An automobile's distributor rotor is situated on the inside of a part called the distributor cap and is connected to the spark plugs by way of the spark plug cables. A vehicle's distributor rotor is a unit that is engineered to distribute an electrical pulse to the engine's spark plugs at the exact moment when it is required. A fully functioning distributor rotor is key in maintaining optimal performance and to getting the most power out of your engine. Your car or truck's distributor rotor is a straightforward device that can be quickly replaced by simply snapping it into place and securing it with a bolt. Hunting for an honest source for outstanding parts such as a Beck Arnley distributor rotor?
A Bosch Distributor Rotor is key in maintaining optimal performance and to getting the most out of your engine.
Looking for a reliable source for trustworthy parts such as a Bosch distributor rotor? If you chose your high-performance vehicle for its awesome power and performance, insure that decision by using first rate new parts. Take your car to a higher level of performance by using performance elements. Superior driving is a snap with high-performance options designed to work with the fuel system and front end components. A car's distributor rotor is a simple device that is no trouble to replace by simply snapping it into place and securing it with a bolt. A distributor rotor is a mechanism that is engineered to dispense an electrical pulse to your spark plugs exactly when it is needed. A working distributor rotor is essential in maintaining optimum performance and to getting the most out of your vehicle's engine. An unreliable distributor rotor will certainly lead to a reduction in a car's efficiency or even prevent the engine from starting. A distributor rotor is positioned inside the distributor cap and is joined to the spark plug cables. Every automobile will need replacement components every so often, so when you need a Bosch distributor rotor, PartsGeek is the place to go to find what you need.
A vehicle's Delphi Distributor Rotor is a unit that is used to dispense an electrical charge to your spark plugs at the exact moment when it is needed.
For outstanding satisfaction from your car or truck, look at a Delphi distributor rotor. By enabling your motorist to burn fuel better, performance parts make for higher horsepower while cutting excess fuel wastage. Support your car's components by installing the most reliable high-quality components. If you bought a high-performance car or truck because it had high-end engine power and performance, support your decision by using high quality replacement parts and accessories. The distributor rotor is a simple mechanical device that can be quickly replaced by simply bolting or snapping it into place. Your automobile's distributor rotor is situated inside a part called the distributor cap and is joined to the spark plugs by way of the spark plug cables. The distributor rotor is a part which is intended to supply an electrical pulse to the engine's spark plugs at the exact moment when it is required. A fully functioning distributor rotor is key in maintaining maximum performance and to getting the most power out of your engine. A faulty distributor rotor may very well lead to a decrease in your vehicle's efficiency or even prevent the vehicle from running at all.
Your Motorcraft Distributor Rotor is a feature that is designed to distribute an electrical charge to the spark plugs exactly when it is needed.
Swing by PartsGeek any time you desire high quality auto and truck parts such as the Motorcraft distributor rotor. Your high-performance vehicle demands the most high-end replacement parts that are available. A car's performance is the result of many factors such as high quality parts. You purchased that high-performance car or truck because it had superb power and performance, back up that decision and install high quality aftermarket parts. An automobile's distributor rotor is a component that is meant to distribute an electrical charge to the engine's spark plugs at the exact moment when it is required. An unreliable distributor rotor may lead to a decrease in your car or truck's efficiency or prevent the engine from starting. The distributor rotor can be found on the inside of a part called the distributor cap and is attached to a set of spark plug cables. A well-maintained distributor rotor is important in maintaining optimal performance and to getting the most power out of your vehicle's engine. Your vehicle's distributor rotor is a straightforward mechanism that is inexpensive to buy and easy to replace by simply bolting or snapping it into place. Any vehicle will need components every so often, so when you need a Motorcraft distributor rotor, PartsGeek.com is here to help you.
The Standard Distributor Rotor is critical in maintaining optimal performance and to getting the most out of your vehicle's engine.
Our specialists here at PartsGeek.com know what it's like to take pride in your vehicle, and so we have made it our mission to help you find the right Standard distributor rotor. Protect your vehicle's critical components by purchasing only the most reliable quality engine parts. People who love performance car or trucks know that nothing is more important than putting in the best new parts for your vehicle. By making it possible for your engine to use gas more efficiently, performance equipment options make for higher power while decreasing excess gas consumption. A vehicle's distributor rotor is a simple mechanical device that is inexpensive to buy and easy to replace by simply snapping it into place and securing it with a bolt. A failing distributor rotor may result in a reduction in your car's efficiency or even prevent the engine from starting. The distributor rotor is installed within the distributor cap and is attached to a set of spark plug cables. A distributor rotor is a mechanism that is designed to dispense an electrical charge to the spark plugs at the exact moment when it is needed. A well-maintained distributor rotor is important in maintaining peak performance and to getting the most power out of your vehicle's engine.
Everyone loves the exhilarating sound of an engine firing up. Encounter a problem, however, and you’ll hear idling, clinking or even nothing at all. The engine is a complicated piece of machinery made of many different components that have to synch up properly for it to work. Intrepid fixer uppers love to dive head first under the hood to get their engine in tip top shape when something is out of whack. If you notice misfires, strange noises or your engine light on your dashboard, it could be a sign of a worn out distributor rotor.
PartsGeek.com is dedicated to providing you with all the accessories you need to make your project a success. We carry the highest quality distributor rotors from the best brands on the market, including Bosch, Standard Motor Products, Beck Arnley, AC Delco, Delphi, Genuine, Accel, Motorcraft, Beru, Bremi, Aftermarket, Dai-ichi and MSD. All parts have a 30-day return policy.
What is a Distributor Rotor?
The distributor rotor works with distributor caps to pass the incredibly high voltage inside an engine from the ignition coils to the cylinders. If this is done properly, the air-fuel mixture ignites and the engine powers on. Typically, the rotor spins inside the cap and is connected directly to the ignition coil. When the tip of the rotor passes a cylinder, a high-voltage spark jumps the small gap between the two components and ignites a spark plug. Because of the large amount of electrical activity, distributor rotors have to be replaced frequently. They are essential for getting good mileage on your vehicle.
How much is a distributor rotor?
The price of a distributor rotor varies depending on the brand and the make and model of your vehicle. PartsGeeks.com offers OEM, aftermarket and replacement parts at discount prices. Distributor rotors range from $7 to $40.
How is a distributor system installed?
Some newer cars have an electronic or computer-controlled distributor that cannot be easily replaced. Plenty of vehicles, however, still include a traditional mechanical distributor. While every vehicle is different, these general guidelines can help you complete an installation:
- Locate your distributor by opening the hood of your car. Ordinary V6 and V8 engines typically have it above them; Inline V6 and V4 engines have it near their side.
- Find the timing specifications of your car by looking in your manual, online or at a sticker under your hood. After your distributor rotor is installed, you will need to use a timing light to adjust the timing of your engine.
- Disconnect the distributor cap by removing the clamps or loosening the screws or bolts.
- Remove all the wires from your rotor. To make sure that you’ll properly reconnect them to the new part, use electrical tape to mark the wires.
- Take a marker and indicate where the rotor was positioned in the distributor housing as well as where the distributor lines up with your engine’s mounting point to make aligning your new part easier. If it’s not aligned precisely, your engine might not start.
- Remove the distributor by removing all the bolts and carefully pulling it away from your engine.
- Remove your new distributor from its packaging and recreate the marks that you made on your old part. Make sure to be as accurate as possible.
- Carefully position the part according to the marks and re-screw the bolts or clamps. Don’t tighten the fasteners all the way; you want your distributor to move a little when nudged
- Re-position the distributor caps and connect all the wires according to the marks you made with the tape.
- Start your vehicle. If you hear a pleasant purring sound, you just completed a successful installation.
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What is a Distributor Rotor?
A distributor rotor is the component in spark ignition systems that routes spark from an ignition coil to the proper contact inside of a distributor cap. This is facilitated by the rotation of a distributor shaft, which typically moves in sync with a camshaft. Rotors can be attached to distributor shafts in a handful of different ways that include both press-on spring clip fittings and screws. Although they share similar names, distributor rotors should not be confused with brake rotors.
Distributor Rotor Construction
Although the rotor design can vary somewhat from one application to another, every rotor has three basic design components:
- a solid body (typically injection-molded plastic)
- a metal contact
- some means of attaching to the distributor shaft
Distributor rotors all have a metal contact on top and some means of connecting to the distributor shaft.
The main body of most distributor rotors is made out of injection-molded plastics that are chosen for their non-conductive and head-resistant properties. This main body has a metal component set into it that serves to provide electrical contact between the central (coil) distributor connector and each outer (spark plug) connector. In some cases, the metal connector is spring-tensioned to provide constant contact to the central connector, and in other cases the central connector itself is a spring-loaded carbon brush.
In most cases, distributor rotors are designed to slip over the outer diameter of a distributor shaft. The shaft is typically keyed in such a way that the rotor can only be installed in one way, which is vital to the proper operation of the ignition system.
Some rotors have metal inserts in their bases, which provides a better connection between the rotor and the distributor shaft, and others simply mate the plastic base to the shaft. The method of securing a rotor also differs from one application to another. Some rotors snap in place with the aid of a spring-tensioned fastener, and others are held in place by a screw or bolt.
How does a Distributor Rotor Work?
Distributor rotors work by providing a movable connection between an ignition coil and a set of spark plugs. When the engine is operating normally, the distributor shaft rotates in time with the camshaft. In turn, the rotor itself turns in time with the distributor shaft. Since the rotor sits inside a distributor cap, it has a constant connection to the ignition coil and an intermittent connection to each spark plug (via the distributor cap terminals and spark plug wires.)
A distributor rotor sits on top of a distributor shaft and spins inside a distributor cap.
As the rotor turns, it periodically makes and breaks contact with the outer terminals inside the distributor cap. If the ignition system is properly timed, a high voltage pulse is provided to the rotor each time it passes one of the outer terminals. An electrical connection is then made between the spark plug, spark plug wire, distributor cap terminal, rotor, and the ignition coil, and the spark plug is able to ignite the air/fuel mixture within its combustion chamber.
Distributor Rotor Failure
When a distributor rotor fails, the engine will typically run poorly or fail to run at all. Most failures are due to wear or buildup on the electrical contacts, both of which prevent adequate (or any) spark at the spark plugs. Excess buildup can be sometimes be cleaned away to extend the life of a rotor, but replacement is typically indicated. Since rotors are wear items, they have to be replaced from time to time due to normal wear and tear.
In some cases, a rotor can fail in other ways. If a rotor spins on the distributor shaft, the ignition timing will no longer be correct, in the same way that rotating the main body of a distributor will change the ignition timing. That can cause anything from a no-start condition, to a poorly running engine, or even severe backfiring, depending on exactly how off the rotor’s orientation is. This may be caused by a bad insert, stressed housing, or a fastener that has backed off.
Replacing a Distributor Rotor
Replacing a rotor isn’t a complicated operation, but they are difficult to reach in some applications. The process of replacing a rotor consists of removing the distributor cap (which itself may be difficult to reach), undoing the fastener (if any is present), and removing the rotor. Installation is simply a reversal of this process, although it is important to make sure that the rotor is installed in the same orientation that it was removed, and that the fastener (if any) is tightened down properly.
What do distributor caps and rotors do in ignition systems?
Distributor caps and rotors are responsible for passing the voltage from the ignition coils to the engine's cylinders in order to ignite the fuel-air mixture inside and power the engine. The coil connects directly to the rotor, and the rotor spins inside the distributor cap. When the rotor's tip passes a contact on the cylinder, a high-voltage pulse travels from the coil to the cylinder via the rotor. That pulse jumps the little gap between contact and rotor and moves on to the spark plug wire, eventually igniting the spark plug on the cylinder. Because of all the high-voltage activity, the rotor and cap have to be replaced relatively frequently. They wear out easily.
The distributor cap and rotor are part of the ignition system, which has to work in concert with the rest of the engine in order to ignite the fuel at the proper time. The idea is to maximize the output of the expanding gases in the engine by lighting them so that they produce heat and the fuel turns to exhaust. The exhaust increases the pressure in the cylinder and pushes the piston down. The idea is to create as much pressure as possible inside the cylinder, thereby maximizing torque and power. Plus, the more efficient the cylinders are, the better the car's mileage will be.
Therefore, the real catch to the coil-distributor-cylinder system is timing. Since there's a short delay between when the spark is created and when it ignites the mixture in the cylinder, the spark has to happen before the piston reaches the top of its stroke. That way, by the time the spark arcs its way across the gap between the rotor and the cylinder, the piston will just reach the top of the stroke and the pressure will be able to build up as it descends into its power stroke.
Originally Published: Jul 27, 2011
This article is about the engine component. For other uses, see Distributor (disambiguation).
Also visible are mounting/drive shaft (bottom), vacuum advance unit (right) and capacitor (centre).
A distributor is an enclosed rotating shaft used in spark-ignitioninternal combustion engines that have mechanically timed ignition. The distributor's main function is to route secondary, or high voltage, current from the ignition coil to the spark plugs in the correct firing order, and for the correct amount of time. Except in magneto systems and many modern computer controlled engines that use crank angle/position sensors, the distributor also houses a mechanical or inductive breaker switch to open and close the ignition coil's primary circuit.
The first reliable battery operated ignition was the Delco ignition system developed by Dayton Engineering Laboratories Co. (Delco) and introduced in the 1910 Cadillac Model 30. This ignition was developed by Charles Kettering and was considered a wonder in its day. Atwater Kent invented his Unisparker ignition system about this time in competition with the Delco system. By the end of the 20th century mechanical ignitions were disappearing from automotive applications in favor of inductive or capacitiveelectronic ignitions fully controlled by engine control units (ECU), rather than directly timed to the engine's crankshaft speed.
A distributor consists of a rotating arm or rotor inside the distributor cap, on top of the distributor shaft, but insulated from it and the body of the vehicle (ground). The distributor shaft is driven by a gear on the camshaft on most overhead valve engines, and attached directly to a camshaft on most overhead cam engines. (The distributor shaft may also drive the oil pump.) The metal part of the rotor contacts the high voltage cable from the ignition coil via a spring-loaded carbonbrush on the underside of the distributor cap. The metal part of the rotor arm passes close to (but does not touch) the output contacts which connect via high tension leads to the spark plug of each cylinder. As the rotor spins within the distributor, electric current is able to jump the small gaps created between the rotor arm and the contacts due to the high voltage created by the ignition coil.
The distributor shaft has a cam that operates the contact breaker (also called points). Opening the points causes a high induction voltage in the system's ignition coil.
The distributor also houses the centrifugal advance unit: a set of hinged weights attached to the distributor shaft, that cause the breaker points mounting plate to slightly rotate and advance the spark timing with higher engine revolutions per minute (rpm). In addition, the distributor has a vacuum advance unit that advances the timing even further as a function of the vacuum in the inlet manifold. Usually there is also a capacitor attached to the distributor. The capacitor is connected parallel to the breaker points, to suppress sparking to prevent excessive wear of the points.
Around the 1970s the primary breaker points were largely replaced with a Hall effect sensor or optical sensor. As this is a non-contacting device and the ignition coil is controlled by solid state electronics, a great amount of maintenance in point adjustment and replacement was eliminated. This also eliminates any problem with breaker follower or cam wear, and by eliminating a side load it extends distributor shaft bearing life. The remaining secondary (high voltage) circuit stayed essentially the same, using an ignition coil and a rotary distributor.
Most distributors used on electronically fuel injected engines lack vacuum and centrifugal advance units. On such distributors, the timing advance is controlled electronically by the engine computer. This allows more accurate control of ignition timing, as well as the ability to alter timing based on factors other than engine speed and manifold vacuum (such as engine temperature). Additionally, eliminating vacuum and centrifugal advance results in a simpler and more reliable distributor.
The distributor cap is the cover that protects the distributor's internal parts and holds the contacts between internal rotor and the spark plug wires.
The distributor cap has one post for each cylinder, and in points ignition systems there is a central post for the current from the ignition coil coming into the distributor. There are some exceptions however, as some engines (many Alfa Romeo cars, some 1980s Nissans) have two spark plugs per cylinder, so there are two leads coming out of the distributor per cylinder. Another implementation is the wasted spark system, where a single contact serves two leads, but in that case each lead connects one cylinder. In General Motors high energy ignition (HEI) systems there is no central post and the ignition coil sits on top of the distributor. Some Toyota and Honda engines also have their coil within the distributor cap. On the inside of the cap there is a terminal that corresponds to each post, and the plug terminals are arranged around the circumference of the cap according to the firing order in order to send the secondary voltage to the proper spark plug at the right time.
The rotor is attached to the top of the distributor shaft which is driven by the engine's camshaft and thus synchronized to it. Synchronization to the camshaft is required as the rotor must turn at exactly half the speed of the main crankshaft in the 4-stroke cycle. Often, the rotor and distributor are attached directly to the end of one of the (or the only) camshaft, at the opposite end to the timing drive belt. This rotor is pressed against a carbonbrush on the center terminal of the distributor cap which connects to the ignition coil. The rotor is constructed such that the center tab is electrically connected to its outer edge so the current coming in to the center post travels through the carbon point to the outer edge of the rotor. As the camshaft rotates, the rotor spins and its outer edge passes each of the internal plug terminals to fire each spark plug in sequence.
Engines that use a mechanical distributor may fail if they run into deep puddles because any water that gets onto the distributor can short out the electric current that should go through the spark plugs, rerouting it directly to the body of the vehicle. This in turn causes the engine to stop as the fuel is not ignited in the cylinders. This problem can be fixed by removing the distributor's cap and drying the cap, cam, rotor and the contacts by wiping with tissue paper or a clean rag, by blowing hot air on them, or using a moisture displacement spray e.g. WD-40 or similar. Oil, dirt or other contaminants can cause similar problems, so the distributor should be kept clean inside and outside to ensure reliable operation. Some engines include a rubber o-ring or gasket between the distributor base and cap to help prevent this problem. The gasket is made of a material like Viton or butyl for a tight seal in extreme temperatures and chemical environments. This gasket should not be discarded when replacing the cap. Most distributor caps have the position of the number 1 cylinder's terminal molded into the plastic. By referencing a firing order diagram and knowing the direction the rotor turns, (which can be seen by cranking the engine with the cap off) the spark plug wires can be correctly routed. Most distributor caps are designed so that they cannot be installed in the wrong position. Some older engine designs allow the cap to be installed in the wrong position by 180 degrees, however. The number 1 cylinder position on the cap should be noted before a cap is replaced.
The distributor cap is a prime example of a component that eventually succumbs to heat and vibration. It is a relatively easy and inexpensive part to replace if its bakelite housing does not break or crack first. Carbon deposit accumulation or erosion of its metal terminals may also cause distributor-cap failure.
As it is generally easy to remove and carry off, the distributor cap can be taken off as a means of theft prevention. Although not practical for everyday use, because it is essential for the starting and running of the engine, its removal thwarts any attempt at hot-wiring the vehicle.
Breaker arm with contact points at the left. The pivot is on the right and the cam follower is in the middle of the breaker arm.
Distributor cap. At the center is a spring-loaded carbon button that touches the rotor. The number of contacts (in this case 4) is the same as the number of engine cylinders
Rotor. This rotates at the same speed as the camshaft, one half the speed of the crankshaft
Top of distributor with wires and terminals
Rotor contacts inside distributor cap
Direct and distributorless ignition
Modern engine designs have abandoned the high-voltage distributor and coil, instead performing the distribution function in the primary circuit electronically and applying the primary (low-voltage) pulse to individual coils for each spark plug, or one coil for each pair of companion cylinders in an engine (two coils for a four-cylinder, three coils for a six-cylinder, four coils for an eight-cylinder, and so on).
In traditional remote distributorless systems, the coils are mounted together in a transformer oil filled coil pack, or separate coils for each cylinder, which are secured in a specified place in the engine compartment with wires to the spark plugs, similar to a distributor setup. General Motors, Ford, Chrysler, Hyundai, Subaru, Volkswagen and Toyota are among the automobile manufacturers known to have used coil packs. Coil packs by Delco for use with General Motors engines allow removal of the individual coils in case one should fail, but in most other remote distributorless coil pack setups, if a coil were to fail, replacement of the whole pack would be required to fix the problem.
More recent layouts utilize a coil located very near to each spark plug known as coil-near-plugs, or directly on top of each spark plug known as direct ignition (DI) or coil-on-plug (COP). This design avoids the need to transmit very high voltages, which is often a source of trouble, especially in damp conditions.
Both direct and remote distributorless systems also allow finer levels of ignition control by the engine computer, which helps to increase power output, decrease fuel consumption and emissions, and implement features such as cylinder deactivation. Spark plug wires, which need routine replacement due to degradation, are also eliminated when the individual coils are mounted directly on top of each plug, since the high voltages and fields exist only over a very short distance from the coil to the plug.
Main article: Wasted spark
The distributor can be eliminated on four-stroke engines by using the wasted spark principle. An ignition pulse is delivered to two cylinders at the same time,chosen so that one cylinder is in an exhaust stroke while the other is about to begin the power stroke. The spark in the cylinder on the exhaust phase is wasted. Each end of the ignition coil winding is connected to a spark plug and they fire in pairs.
A single-cylinder engine has only one spark plug and so needs no distributor. Ignition systems on such engines may produce a wasted spark during the exhaust stroke.
|Look up distributor in Wiktionary, the free dictionary.|
How Long Does a Distributor Rotor and Cap Last?
The distributor rotor and cap pass voltage from ignition coils into the engine’s cylinders. From here, the air/fuel mixture is ignited and powers the engine. The coil connects to the rotor and the rotor rotates inside of the...
The distributor rotor and cap pass voltage from ignition coils into the engine’s cylinders. From here, the air/fuel mixture is ignited and powers the engine. The coil connects to the rotor and the rotor rotates inside of the distributor cap. When the tip of the rotor passes a contact on the cylinder, the high voltage pulse goes from the coil to the cylinder through the rotor. From there, the pulse moves from the gap an onto the spark plug wire, where it eventually ignites the spark plug on the cylinder.
The distributor rotor and cab are subjected to high voltage on a regular basis, meaning every time you turn on your vehicle, electricity flows through them. Because of this, they do wear out from time to time. When the distributor rotor and cap are replaced, the entire ignition should be inspected to ensure everything else is in good working condition.
Preventative maintenance is key to catching your distributor rotor and cap failing. Every time your vehicle has routine maintenance or is serviced by a professional, the ignition should be thoroughly inspected. In addition, this part is more likely to fail if you drive through a deep puddle because water will get into the distributor cap and short out the electrical current. The cap may not need to be replaced if this is the case, it may need to just dry out for a certain period of time. If you are unsure or if you start to notice any problems with your vehicle starting up, you can always schedule an inspection from a professional mechanic. They will thoroughly inspect your system and replace the distributor rotor and cap.
Since the distributor rotor and cap can go bad over time because they are located in a harsh environment, it is important to know the symptoms this part will give off before it completely fails.
Signs you need your distributor rotor and cap replaced include:
- The Check Engine Light comes on
- The car does not start at all
- The engine misfires and has trouble starting
The distributor cap and rotor is an essential part to starting your vehicle, so the repair should not be put off.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Honda Civic L4-1.6L - Distributor Rotor and Cap - Nashville, Tennessee
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Chevrolet Express 1500 - Distributor Rotor and Cap - Nashville, Tennessee
Effective and professional great to work with will always ask for Jason great job van runs better than ever thank you for your help
Nissan Frontier V6-3.3L - Distributor Rotor and Cap - San Jose, California
He came a little earlier than expected & is very efficient. He explains what he does & needs to be done.
Dodge Ram 1500 V8-5.9L - Distributor Rotor and Cap - Battle Ground, Washington
Tim and his father in law did a great job working on my truck. Thanks for your services. My invoice was incorrect for the oil change because I never got one done and I purchased my own Distributor Cap with Rotor and Coil. Your Mechanic only provided me parts for my Spark Plugs n Spark plug wires. But Tim said he fixed my invoice and I believe he will.
Chevrolet Express 1500 V6-4.3L - Distributor Rotor and Cap - Dayton, Ohio
Matthew (goes by Jake) was excellent, as was our experience with Your Mechanic. We booked on a Thursday and he came to us on Friday, and then he came back for follow-up services on Monday and Tuesday. He was knowledgeable about all of our vehicles and was very willing to show and talk about the services that he provided. We will definitely book him again!
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Symptoms of a Bad or Failing Distributor Rotor and Cap
A running engine sends a large amount of electricity through the ignition coils to the rotor, which turns inside the distributor. The rotor routes the energy in a specific through the spark plug wires ultimately to the engine’s cylinders in the correct firing order.
The distributor rotor and cap keep the distributor’s contents separate from the engine and keep the distributor’s working parts clean and tidy – while supporting the incredibly high volts of energy and delivering them to the appropriate spark plugs. The spark plugs utilize the spark from the distributor to ignite the fuel mixture, which is what keeps the engine running.
High voltage runs through this entire distributor system during the operation of your vehicle, but if there's an issue this voltage won’t get distributed to the correct spark plugs to ensure that your engine will run. Usually a faulty distributor rotor and cap will produce a few symptoms that alert the driver that service may be required.
1. Engine misfires
Engine misfires can occur for a number of reasons. Checking your distributor rotor and cap to see if they need to be replaced is one way to ensure that everything is in solid working order.
2. Car doesn’t start
When the distributor cap isn’t on tightly or is malfunctioning, the engine is unable to send the spark through the entire circuit required to move the cylinders – which ultimately make the car run.
3. Check Engine Light comes on
Your Check Engine light can mean a number of different things, but when you see this light on along with some of the other symptoms listed here, it’s time to call a professional to see what the code is from your car’s computer.
4. Excessive or unusual engine noises
Your vehicle may make some very strange noises if the distributor rotor and cap are malfunctioning – specifically because the cylinders will try to fire but fail. You might hear a tapping, clicking, or sputtering sound when the distributor rotor and cap are failing.
Any time you have routine service performed on your vehicle, ask that the ignition system be checked for defects or problems. If you experience any trouble starting your car get assistance from a qualified mobile automotive technician from YourMechanic.
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This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Distributor Rotor and Cap.
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