Why there is no spark on the spark plugs: troubleshooting in the car ignition system

Bringing the car back to life

As for why a spark disappears, everything is probably very clear. Now, it would not be amiss to consider the order of her return. The reality is that in most cases, getting the spark back is a simple matter and just involves carefully checking the broken car. To be more precise, to normalize sparking it is required:

1. Firstly, check the spark on the injector using the method described above, make sure that it has disappeared, and, at least indirectly, try to determine the cause of the malfunction;
2. Next, it is enough to assess the current circumstances and act based on them. As typical situations, we suggest considering solutions to the following problems:
   the spark plug is wet, the presence and strength of the spark are unimportant, the carbon deposits are correct (brick color) - wipe the part and screw it back in;
3. the spark plug is wet (not always) and the carbon deposits are incorrect (white or black) - clean, dry the part and try to start the engine, if there is no result, change the spark plug and deal with problems in the fuel system (cleaning the injector, checking the ECU, etc.);
4. the spark plug is wet, there is no spark at all, the color of the soot is not important - we try to change the part, if there is no result, we check the ignition system and the operation of the injector.

In principle, in theory there are no particular difficulties in repairs of this kind. Despite this, it often causes difficulties in implementation for inexperienced motorists. To solve these, you need to act in the order described above, but if something doesn’t work out, it’s better to turn to professionals at a service station. This approach to repairs will not only save time, but also guarantee trouble-free operation of the car in the future.

Perhaps this concludes the most important information on today’s issue. We hope that the material presented was useful to you and provided answers to your questions. Good luck in operating and maintaining your car!

Signs that you need to check the spark plugs for a spark

An unscheduled check of spark plugs is always associated with incorrect engine operation. We carry out an inspection if we notice the following signs during vehicle operation:

1. The engine starts to start after a long rotation of the starter or does not start at all.
2. The engine idles intermittently, idles, and jerks while driving.
3. Fuel consumption increases.
4. The dynamics deteriorate, the engine loses power.

A negative consequence of a malfunctioning spark plug is the accumulation of the fuel mixture in the combustion chamber and its detonation. This will lead to deformation of the connecting rod, breakage of the pistons, crankshaft and other components of the power unit.

How to check spark on spark plugs?

The following engine parameters directly depend on the quality of the spark:

• fuel consumption;
• throttle response of the power unit;
• engine wear.

Timely checking of spark quality is necessary during vehicle operation.

Causes and signs of incorrect sparking

The main reasons for the violation of spark formation in gasoline engines are:

• spark plug wear;
• incorrect setting of the ignition angle;
• malfunction of the ignition system (coils, high-voltage wires, distributor, crankshaft and camshaft sensors);
• reducing compression in cylinders;
• suction in the air intake system;
• refueling with low-quality gasoline;
• incorrect operation of the gas distribution mechanism;
• malfunction in the engine control system.

The main signs indicating the need to check the spark:

• misfires;
• "triple" of the engine;
• reduction in throttle response of the power unit;
• changes in the color and composition of exhaust gases;
• engine error message on the dashboard.

In any of the above situations, you must first check the spark.

Control methods

There are several methods to check spark quality:

1. Visual control method. To carry it out, it is necessary to dismantle the spark plug. It is advisable to do this on a warm engine. After dismantling, the quality of the soot is visually assessed. If there is a light gray or light brown small deposit, sparking is probably occurring normally. A “wet” working area indicates a lack of spark. Large black deposits are a sign of incorrect ignition angle setting. At the same time, the size of the gap in the working area and the integrity of the structure are checked.

2. Checking spark formation without dismantling the spark plug using a practical method. This method is used by experienced professionals with special precautions. To do this, start the engine. Next, the high-voltage wires are disconnected and connected one by one. In the case of individual ignition coils, the connectors to them are disconnected. If after switching off the character of the engine operation has changed, then the spark plug is working. If the quality of the engine has not changed, most likely the device is inoperative.

3. Check by replacement method. With this method, adjacent candles are swapped. If the misfires are also “swapped”, the device does not work.

4. Parametric control. The high-voltage pulse on the spark plugs reaches 20 thousand volts. It is problematic to measure it directly with conventional measuring instruments. You can evaluate the quality of the pulse using a neon light bulb connected through a resistor.

5. Checking the spark in operating mode. To do this, use an additional candle, which is installed in place of the one being tested. The candle being tested is dismantled and connected to a high-voltage wire (individual coil). Establish reliable contact between the spark plug mass and the metal base of the engine. The engine is started. Control sparking visually. It is better to carry out such a check in the dark, taking maximum safety measures.

6. Computer diagnostics of modern cars allows you to determine misfires in specific cylinders.

How to check the spark on a fuel-injected engine

One of the most important parts of your car's electrical system is the spark plugs. These parts ignite the fuel, and if the spark plugs stop working properly, the engine will experience certain problems. The spark plugs themselves do not break so often; most likely, other factors are to blame for the lack of a spark.

However, sometimes a candle that has already exhausted its service life cannot properly perform its working functions. Therefore, it is advisable for every driver to know how to check spark plugs on the road without special tools and diagnostic equipment.

The best way to check spark plugs is through timely maintenance and regular servicing of the machine.

The first symptoms of faulty spark plugs and lack of spark

The reasons for the failure of spark plugs in a car can be very different. But the symptoms are similar in most cases. The main indicator of the failure of one spark plug is that the engine begins to stall. When such an unpleasant aspect occurs, the power of the unit decreases, consumption increases, and the car shakes a little at idle. All this allows us to conclude that one of the cylinders is not working, in particular because there is no spark at the spark plug. The following symptoms of non-functioning spark plugs are also distinguished:

the car does not start, when you try to start the engine, the starter spins smoothly, there is no progress in the ignition; after starting, 2 or 3 cylinders work for some time, then the fourth one is connected - this is an indicator of the failure of the spark plug; the car constantly becomes difficult to start, the engine only starts on the third attempt; the car has lost power and responsiveness, pressing the gas pedal does not produce the desired effect; the car stalled during the trip, starting it is difficult or even impossible;

From time to time, during startup, strong pops are heard in the exhaust pipe - this is the fuel that has been pumped up but not burned.

When all the spark plugs do not work, this situation should alert the car owner. Most likely, the reason is not the spark plugs. But if one spark plug refuses to work, you should look at the spark plug itself, as well as at the wire that connects it to the coil. This will help you find out what exactly caused the problem in your car. And if testing sensors, switches and coils in the field is not an easy task, then testing spark plugs is quite possible.

How to check spark plugs without special equipment?

On the road, we often don't have any equipment to test spark plugs. Therefore, you have to make do with traditional methods to check all the subtleties of the car. In particular, in the case of candles, you can use one of the proven testing methods. First, you should unscrew the spark plug and take a closer look at it, obtaining information about its condition. If the spark plug is wet, it floods with gasoline and does not work. A dry spark plug means there is no fuel getting to it or everything is working properly. A black candle wick also indicates a problem. You can check for spark as follows:

unscrew the spark plug and put a high-voltage wire on it so that you can give a spark; grab the rubber part of the wire with your hand, but in no case grab the metal parts of the spark plug; place the spark plug wick at a distance of about 0.5 centimeters from the engine body - any metal parts; ask another person to turn the ignition key and try to start the engine for four seconds; if a spark appears and breaks through to the engine body, then everything with the spark plugs is in perfect order, you need to look for other problems;

if there is no spark, the spark plug does not work, and other not very pleasant problems are also possible.

If there is a spark, then the engine starting problem is related to the fuel system. If there is no spark, the culprit of your problems is the vehicle's electrical system. These will not necessarily be spark plugs, because the electrical system of a car contains quite a few different elements that can damage the spark plug assembly. You need to check everything to fully ensure that the equipment is working properly. By the way, the easiest way to check whether the spark plugs are working is to replace them with ones that are known to work.

What else could cause the spark plugs to not spark?

If there is no spark, many drivers confidently say that they need to change the spark plugs. But this is not always true. In particular, there are other modules that can affect spark production, so you need to check all the features of the vehicle's electrical system. If we are talking about the fact that the ignition system does not produce a spark, it is necessary to pay special attention to those modules that are responsible for this spark. Among them, you will have to check and suspect a malfunction of the following important machine modules:

high-voltage wires - often this element is the reason for the lack of a spark, the wire can pierce; ignition coils or distributor on old cars - frequent candidates for replacement and repair; switch - a part that rarely raises doubts about its operation; it breaks not so often, but very unexpectedly ;ignition switch - one of the contacts may move away and not give normal commands to the car engine;

an on-board computer that controls the actions of the vehicle's electrical system, including the ignition.

If one of these elements fails, the symptoms will also be similar to a simple spark plug failure. But replacing the spark plugs will not have any effect. If the switch or on-board computer breaks down, you will have to contact specialists and carry out quite expensive repairs. You cannot solve such problems on your own. It is also difficult to replace ignition coils in the field. However, this list of problems is not exhaustive.

Why is there no spark at the spark plugs?

There can be several reasons for the lack of spark at the spark plugs. Most often the culprits of the malfunction are:

1. Accumulator battery;
2. High voltage wires;
3. Ignition coil;
4. Distributor;
5. Malfunctions in the low voltage circuit.

Also, in the absence of a spark, special attention should be paid to checking the quality of contacts and electrical connections of the ignition system elements. You can check the condition of the contacts simply by rubbing them with your hand.

Carefully inspect the wires and blocks of the ignition system - if dirt, oil or water is found on them, they must be wiped with a dry cloth. After that, try starting the engine, it may start this time.

Checking the battery

A clear sign of problems with the battery is a dull and quiet horn signal. Also, if there are problems with the battery, the indicator lights on the instrument panel usually go out while the starter is rotating. In this case, the reason for the lack of a spark may be poor contact at the terminals or a low battery charge.

• If the terminals are oxidized, they must be cleaned and tightened tightly. In addition, you can use graphite lubricant, which will reliably protect the contacts from oxidation in the future.
• If the battery is discharged, it must be charged using a charger.

For information on how to properly charge a car battery and maintain it, read our battery charging instructions.

Checking high voltage wires

Next, it’s worth inspecting the high-voltage wires: they must have a neat, not “tattered” appearance, without insulation damage, otherwise they will have to be replaced. If the wires are ok, then you can start looking for a spark.

We recommend starting your search for a spark with the spark plug wires. To do this, you need to remove the tip of the spark plug wire from the spark plug and bring it to the “ground” (the nearest unpainted metal part of the body or engine) at a distance of 5-8 mm, after which you need to turn on the starter for a few seconds.

The rotation of the starter should be accompanied by an uninterrupted bright spark of white color with a slight blue tint. If there is no spark, you need to check the ignition coil. A violet, red or yellow spark indicates a malfunction in the ignition system.

It is also worth noting that the spark plugs themselves rarely fail all at the same time. If there is a “spark” in the spark plug wires, you can check any spark plug by unscrewing it from the cylinder head and putting the spark plug wire on it. Touch the metal part of the spark plug to the “ground” of the car, and by rotating the starter, make sure that there is a spark at the spark plug electrodes.

It is necessary to change spark plugs within the time limits established by the maintenance regulations for your car (usually every 15-25 thousand km).

You can learn more about the markings and heat ratings of spark plugs from our material at this link.

Checking the ignition coil

To check the ignition coil, you need to pull out the central wire coming from the coil from the distributor-breaker cover.

While turning the starter, make sure there is a spark from the wire, similar to the spark plug wires.

• The appearance of a spark indicates the serviceability of the ignition coil. In this case, the fault should be sought in the distribution switch.
• If there is no spark from the wire, then the cause of the malfunction is hidden either in the ignition coil or in the low voltage circuit.

If there is a malfunction in the ignition coil, it should be replaced with a new one.

Checking the ignition distributor

If you suspect a malfunction of the breaker-distributor, you must carefully inspect its cover from the inside.

• If the cap is in order, then simply wash it with gasoline,
• If any cracks are found, the cover will need to be replaced.

The center carbon contact of the breaker is checked for sticking by lightly moving it with your finger.

The rotor insulation of the breaker-distributor is checked for breakdown as follows:

1. Place the central high-voltage wire with a gap of 5-8 mm from the rotor electrode,
2. After this, close and open the breaker contacts with your hand (the ignition must be turned on).

The appearance of sparks in the gap indicates a rotor malfunction that will need to be replaced.

Low Voltage Circuit Test

To check the low voltage circuit, you can use a 12 V test lamp with a power of up to 3 W. The lamp is connected on one side to the low voltage terminal of the breaker, and on the other to the vehicle ground.

After this, you need to manually close the contacts of the distributor-breaker and turn on the ignition. If the low voltage circuit is working properly, the control lamp should light up when the contacts open, and go out when they close.

If the lamp does not light up when the contacts are opened, it means that the fault is hidden either in the low voltage wires or in the primary winding of the ignition coil.

Constant lighting of the lamp, in any position of the contacts, indicates one of three causes of the malfunction:

1. Severe oxidation of breaker contacts;
2. Broken wiring leading from the breaker terminal to the lever;
3. Broken wiring connecting the movable disk of the breaker to the housing.

If the cause of the malfunction turns out to be oxidized contacts, then they must be cleaned, after which the gap should be adjusted.

How to check the spark on a spark plug

Even modern cars with injection engines and an abundance of on-board electronics are not immune from periodic problems. Quite often there are interruptions in the engine idling, or difficulties in starting the engine are noted, regardless of the ambient temperature. If you hear the noise of the fuel pump when you try to start, the first thing you should do is check the functionality of the entire ignition system, without relying on the on-board computer and sensors.

First of all, as practice shows, you will need to check the spark plug spark, since its “disappearance” is the most common cause of poor starting and unstable engine operation. It is necessary to understand that when checking it yourself, it is important to take special care, since in addition to the possibility of receiving an extremely unpleasant electric shock, you can damage the ignition module or controller. Therefore, it is advisable to carry out the test using a special spark gap, which you can make yourself.

How to check spark on ignition coil

The ignition coil is not one of those units that constantly breaks down and causes other troubles, but in some cases problems are still noted. The most common cause of problems is winding damage. The subsequent breakdown of the insulation layer leads to a short circuit. The coil can also be damaged as a result of overloads caused by faulty spark plugs, or defects in the high-voltage wires themselves.

Before checking the spark on the ignition coil, it is advisable to drive the car into a dry garage. All work can be done independently, without the use of special equipment. The algorithm for such a check is standard.

1. After cleaning the distributor cover from dirt, it is removed.
2. By turning the crankshaft on the engine, it is necessary to achieve the closure of the distributor contacts.
3. After turning on the ignition, the high-voltage wire coming from the distributor is brought to the ground of the vehicle. Particular attention should be paid to the distance - it should be 5 mm.
4. To ensure the accuracy of the coil test, from time to time you will need to manually open the contacts of the distributor.

5. You can say that the coil is working properly if a bright blue spark appears. If it is weak, uncertain, appears only periodically or is completely absent, the coil must be replaced, since its repair, as a rule, is simply impossible. When installing a new one, the polarity must be strictly observed, otherwise the new coil will also fail. At specialized service stations, coils are checked on a special stand, which allows testing the performance of the device in various operating modes. A very simple way to quickly check is shown in the video:

Ignition coil: how to understand that there is no spark in it?

Before you begin to understand this issue, it is important to understand exactly what this node actually is. In principle, its main purpose is to convert current from low to high voltage. Well, if this element has any problems, then it will be impossible to start the vehicle. However, this mechanism, in the presence of disturbances, has its own characteristic symptoms. You can recognize that there is no spark in the coil by the following signs:

• There was a decrease in engine power;
• There were problems starting up;
• Fuel consumption has increased sharply;
• Periodically there are interruptions at idle.

If the motorist has identified the problem, and it turns out to be related specifically to the coil, then the next step is to begin repairs. It is quite possible to solve this problem yourself, without resorting to the help of service center specialists. First, the driver needs to inspect the element for any possible violations. Next, if, for example, dirt is found on the coil, it will need to be removed with a dry cloth. It is also very important to pay attention to the wiring itself. There should be no accumulation of moisture and various breaks on it.

More details about checking the ignition coil for functionality will be described in this video:

No spark at the spark plugs

Before troubleshooting, it is necessary to more specifically determine the culprit for the loss of spark and conduct a visual inspection of the high-voltage wires, ignition coil and distributor. A trivial central armor wire that has slipped off the distributor cover, a loose connector, or an oxidized (fallen off) terminal on the ignition coil will lead to the disappearance of the spark.

Then we remove the central high-voltage wire, insert a working spark plug into its tip and place it on the engine (so that there is contact with ground). While the assistant turns the engine with the starter, you need to visually verify the absence or presence of a spark at the spark plug. A spark has appeared - the spark plugs themselves, the high-voltage wires or the ignition distributor in the distributor are faulty. There was still no spark - problems with the switch, Hall sensor, ignition coil.

Lost spark, reasons for contactless ignition system

1. The ignition coil has failed.

Checking the ignition coil. The ignition coil is usually checked for winding resistance and insulation resistance using a tester. For oil-filled coils (27.3705) and dry coils (3122.3707), the resistance is slightly different. Read more: “Checking the ignition coil.” In the absence of a special device for testing, we use the method of replacing our coil with another one that is known to be good.

checking the primary winding of the ignition coil

1. The switch is faulty.

Checked with an oscilloscope. Since not everyone has it, we use the replacement method - instead of our switch we install a known good one. You can very roughly estimate the performance of the switch based on the voltmeter readings after turning on the ignition (see “Checking the switch”).

1. Hall sensor is faulty.

It is checked with a voltmeter according to a special connection diagram (see “Checking the Hall sensor”). If there is no voltmeter, we use the replacement method.

Hall sensor, check

1. Open circuit in low voltage circuit.

Using the diagram, we look through the wires included in the ignition system, and if necessary, “ring” to detect a “break.” See "Contactless Ignition System Diagram".

In the contact ignition system, the list of malfunctions leading to the disappearance of the spark is as follows:

1. The mechanical breaker in the distributor is faulty.

Its contacts have oxidized, collapsed or burned. There is no gap between the breaker contacts.

breaker contacts

1. The ignition coil is faulty.
2. "Open" in the low voltage circuit.

Notes and additions

— To quickly find the reason for the disappearance of the spark on the spark plugs, you need to know the principle of operation of both contact and non-contact ignition systems (for more details, see “The principle of operation of the ignition system”). The purpose of the ignition system is to generate high voltage current at the right moment and supply it to the spark plugs. This is accomplished by interrupting the low voltage current in the primary winding circuit of the ignition coil. In a contactless system, the switch interrupts the current based on a signal from the Hall sensor; in a contact system, a mechanical breaker with contacts is driven by a tetrahedron on the distributor shaft.

More articles on the ignition system of VAZ cars

How to check spark strength on the ignition module

Most car owners understand that when the engine starts to stall or has trouble starting, the problem is often a lack of spark. Therefore, checking the spark on the injector is a manipulation that should not cause any difficulty for the driver, who often has to deal with the need for repairs in the field. Naturally, you should always have a set of several new, or simply working, candles with you.

Since the lack of a spark is the most common cause of the engine stalling or difficult to start, as well as unstable idling, checking the spark on the spark plugs is carried out by motorists first. In order not to turn out all the spark plugs at once, you can check them one by one - removing one by one from the cylinder head, putting caps on them with a wire from the coil and grounding each spark plug to ground. Rotating the starter should produce a nice, bright spark. If it is missing, you can replace the wire (it is advisable to carry a spare one with you) or use one that is known to be working.

When removing high-voltage wires from the module, it makes sense to number them first - this will avoid confusion in the future. Problems caused by the spark plug or wires become obvious in this way. If a spark does not appear on the spark plug, the problem lies in the module itself. In order to accurately determine this, the “replacement” method will help - the working module can be temporarily “borrowed” from another car of the same model. If replacement fixes the problem, you can safely go to the auto store for a new one.

Weak spark at the spark plugs. What to do?

Failure of spark plugs leads to interruptions in engine operation. The first sign is a weak spark at the spark plugs. Let's disassemble the ignition unit to find the missing spark.

Why is there a weak spark at the spark plugs?

First, check the unit for wet marks (remove with a lint-free cloth).

Sometimes this manipulation turns out to be a solution and the engine starts.

We list the possible sources of difficulties:

• battery;
• BB wires;
• low voltage circuit;
• coil;
• distributor;
• weak electrical connections;
• ECU and so on.

What to do?

Based on the advice of experienced car enthusiasts, we suggest checking the possible causes of the malfunction. First of all, use a spark gap to know where exactly the spark disappears. If the cylinders are faulty, pay attention to the controller, the module as a whole, or the coil.

Start with a visual inspection of the high-voltage wire (the ideal is good external condition with intact insulation). Repair or replace the element as necessary.

If the problem is not found, we go directly to the SZ. Clean or replace rusty contacts if necessary. Before making a decision, test the presence of a discharge on the spark plugs: bring the wire 0.5 cm to the metal and spin the starter. A blue-white spark signals normality. Another color (purple, for example) - go to the coil (KZ).

The operation of the coil is tested in the same way as the discharge on spark plugs (see above). Two scenarios:

• sparked - see distributor-breaker (R/P);
• did not “ignite” (deal with the coil).

Checking the ignition coil for spark

To diagnose the performance of the coil, remove the wire from the distributor-breaker. Next, the test is carried out similarly to testing high-voltage wires, that is, the wire is brought to a metal surface and turned with a starter. The presence of a spark will indicate in this case a problem with the ignition distributor; if there is no spark, then the problem lies in the coil.

First you need to check the distributor contacts. These contacts may oxidize, insulation damage is also possible, and the rotor itself may be faulty. Detecting problems with the rotor allows you to eliminate the problem by replacing it. When checking the ignition coil, you should identify possible defects in the integrity of the winding, burnouts and other signs that a short circuit is occurring inside. If such signs are found, the coil should be replaced or the ignition coil should be repaired.

Let us add that the presence of a spark on the spark plugs does not mean that the car must start. This is especially true for injection engines, where the failure of certain sensors or ECUs can make it very difficult or completely impossible to start the power unit. In such cases, there is a spark, fuel is supplied, but the engine still does not start. The ignition switch also deserves special attention, since malfunctions can occur in this place.

Now let's take a closer look at ways to check the main elements of the ignition system. To do this, let's go back to the coil. As already mentioned, the most common cause of a malfunction is a damaged winding. Then an insulation breakdown occurs and a short circuit occurs. It is also important to understand that the coil can fail due to overload. Such increased loads occur as a result of problematic spark plugs or spark plug wires. For diagnosis you should:

• put the car in a dry parking, repair or other box. You can also use the garage. The main thing is that the humidity is not too high;
• Next, you will need to clean the distributor cover from dirt, after which the specified cover must be removed;
• then you need to turn the engine crankshaft so that the distributor contacts are closed;
• Now you can turn on the ignition and bring the high-voltage wire of the distributor 3-7 mm to ground;

After evaluating the spark, you can decide whether the ignition coil needs to be replaced. Please note that repairing this element is often impractical. Also, when installing a new spare part, you should strictly adhere to the required polarity. If this is not done, then the new part will quickly become unusable after unqualified installation. Please note that car service centers use a special stand to check coils. Such equipment allows you to check the coil taking into account various operating modes.

To check the spark on the spark plugs if the distributor is working properly and there are no problems with the condition of the high-voltage wires, you need to unscrew the spark plugs from the engine. In addition to the contacts, you should look at carbon deposits, the degree of oiling of the electrodes, etc. For normal sparking, contamination must be cleaned. You should also check the gap between the electrodes, which is usually between 0.7 and 0.9 mm. If the gap is broken, then you can carefully bend the side electrode. This method is a temporary measure, but in some cases it allows you to drive from several tens to hundreds of kilometers without tripping the engine in case of problems with the spark plugs.

We also add that there are special pistol devices for checking spark plugs. Typically, such solutions are available from spark plug sellers in car dealerships or automotive markets. If there is such a possibility, then the spark plugs can be checked on similar equipment.

What to do

If the engine runs or starts poorly, motorists are interested in how to strengthen the spark on the spark plugs. First, you need to establish the cause of the breakdown by checking the previously mentioned components and elements using a multimeter and visual inspection. Many faults can be seen by eye.

Often, a simple replacement of spark plugs or glow plugs can help improve the spark (depending on the type of internal combustion engine (petrol or diesel). It is advisable to buy elements from well-known manufacturers in the mid-price category, beware of counterfeits. Faulty spark plugs can often be identified by their appearance. In addition, their replacement is required with the following symptoms:

• Engine tripping.
• Poor starting of the power plant, especially in cold or wet weather.
• White smoke from the exhaust pipe of a car with a diesel engine.
• Reduced vehicle dynamics.
• Increased fuel consumption.

Checking the Low Voltage Circuit Condition

This is also not a superfluous event when it comes to the absence of a spark on the candles. To carry out such a diagnosis, you will need a test lamp. Moreover, choose a device with a power of 2-3 W and a voltage of 12 V.

One contact from the control unit is connected to the low voltage contact of your distributor, and the second goes directly to ground. Now you need to close the distributor contacts and start the ignition. If there are no problems in the circuit, then at the moment the contact closes, the lamp must go out. In this case, it lights up only when the contacts open.

If, after opening the distributor contacts, nothing happened, that is, the control lamp did not light up, the cause of the malfunction most likely lies in the breakdown of the primary winding of the coil, or in the low voltage wires.

There are situations when the control lamp shines constantly during diagnostics, without interruption, regardless of the opening or closing of the contacts. Here you should consider one of several potential reasons for this behavior of the warning light:

• the contacts on the distributor have oxidized, which need to be frequented and, if possible, lubricated with graphite lubricant;
• the wires that connect the movable disk of the distributor and its body are damaged;
• other wiring located between the distributor terminal and the lever was damaged.

The test should always be carried out in stages, starting from the most likely faults, and ending with those that are much less likely to cause a lack of spark.

Do not rush to make the worst and most unpleasant diagnosis for your ignition system. It often happens that the reason lies in banal carbon deposits on spark plugs or blown fuses.

The quality of the spark on the spark plugs is checked in the same way as in its absence. However, it is advisable to change the gap with the high-voltage spark plug wire and ground. A spark is considered good if it penetrates a gap of at least 7 mm.

A weak spark on the spark plugs is a malfunction that occurs just as when there is none at all, but it is much more difficult to detect the cause of its occurrence. An ammeter won't even be able to help in this case. The best way to determine a malfunction is to turn off a particular device or section of the circuit from the ignition system and try, if possible, to get a spark without them. The appearance of a good spark indicates a malfunction of the switched off device.

When, after checking, it turns out that the spark between the spark plug and the high-voltage wire is weak, turn off the distributor from the ignition circuit and check the quality of the spark between the ground and the high-voltage wire of the ignition coil. The presence of a strong spark indicates that the entire ignition system to the distributor is working, except for the distributor cap, rotor or high-voltage spark plug wires. If these parts are cracked or broken, they must be replaced.

If, when disconnecting the distributor, the spark remains weak, as before, you should carefully check all the clamps of the low voltage circuit, the cleanliness and reliability of the fastening. If, even after checking the terminals, the spark is weak, it is necessary to turn off the breaker from the low voltage circuit. Its action can be replaced with an additional wire, one end of which is connected to the point of connection of the capacitor wire with the low voltage wire coming from terminal P of the ignition coil, and the other is sharply struck to ground. In this case, the ignition coil wires and the capacitor must be disconnected from terminal K of the breaker.

The occurrence of a strong spark between ground and the high-voltage wire of the coil without the action of the breaker indicates a malfunction of the breaker.

To check the safety and reliability of contact and isolation of current-carrying parts of the circle from ground, you need to check the inner circle of the breaker, the condition and gap in its contacts at all cam protrusions. When checking the inner circle of the breaker, determine whether the cam, the bushings of the breaker shaft, the axis and the hole for the axis of the breaker lever have not worked, and that the breaker panel is securely seated on the bearing.

If the spark is weak and irregular when the breaker is off, then the capacitor or ignition coil is most likely faulty. After making sure that the capacitor is in good condition, you should check the serviceability of the ignition coil. Strong heating of the ignition coil indicates a short circuit in the primary winding. The faulty coil is replaced.

Similar

Useful tips

Experienced car enthusiasts are well aware that spark plugs can fail at the most inopportune moment. For this reason, it is recommended to carry a spare set with you. The same can be said about the spark plug wires.

When working on the ignition system, extreme caution should be exercised as you may receive a severe electric shock. Insulated tools must be used.

Since spark plugs fail more often than other elements of the ignition system, checking for a spark always begins with them. Diagnostics can be done one by one. The procedure is carried out by unscrewing the spark plug from the cylinder head, then putting a cap and a wire from the coil on the spark plug, after which it is grounded to ground. The main indicator when checking while the starter is rotating is the spark itself and its quality.

When removing the spark plug wires from the ignition module, it is advisable to mark each wire. This will allow you to check and subsequently connect in a strictly defined order without the risk of mixing up the wires.

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When the spark is lost, you will, of course, never start the car, and in such a situation, first of all, you need to check the ignition system.

The vehicle's ignition system plays a key role in its operation. If in case of many other malfunctions the car can be taken under its own power to the service station, then in case of problems with the ignition it is unlikely that it will be possible to start the engine at all.

Typical causes of spark loss

Depending on the type of powertrain, there are several factors that can cause the spark plugs to fail to spark. In most cases the reasons are as follows:

1. Low battery.
2. Damage or failure of spark plugs. They can also be filled with gasoline or oil.
3. Malfunction of the module, switch or ignition coil.
4. Poor contact or damage to the insulating layer of high-voltage wires.
5. Malfunction of the crankshaft position sensor (CPS).
6. Malfunctions in the operation of the distributor.
7. Problems in the low voltage circuit.
8. Poor ground contact.
9. Malfunctions in the operation of the engine ECU (electronic control unit).

The main reasons why there is no spark

• problem with spark plugs (flooded or faulty);
• breakdown of high-voltage wires or loss of contact;
• the reason is the crankshaft sensor (requires checking with a multimeter);
• malfunction in the ignition module;
• failure of the ignition coil;
• problem in the switch;
• Distributor malfunction (burned contacts, loss of clearance);
• poor ground wire contact;
• failure or malfunction of the ECU.

External signs and corresponding malfunctions of the contactless ignition system

Why is there a weak spark on the spark plugs?

The spark can be weak for various reasons. The main ones are malfunctions:

• Spark plugs.
• Ignition coils.
• Battery.
• High voltage wires.
• Low voltage circuits.
• Electronic control unit.
• Distributor.

Sometimes the problem can occur due to loose connections between the wires and the vehicle's electronic equipment. Problems sometimes arise for other reasons. But the first thing you should do is check the engine compartment for moisture. Often it is enough to wipe them with a rag to restore the functionality of the candles. But on heavily used cars with high mileage, increasing spark power without some modifications is not always possible, even if the above parts and assemblies are in full service.

Faulty spark plug

Other breakdowns and their elimination

If the engine does not start when the ignition is turned on, then, first of all, you need to turn off the ignition system and try to start the engine again after a few seconds. If all this does not give any results, perhaps it makes sense to check the correct installation of the spark plugs - it could very well turn out to be incorrect. If all these actions do not produce any results, then the entire system will have to be thoroughly checked. It may also turn out that the cause of the malfunction is in the distributor cap. It must be carefully dismantled and both sides thoroughly checked. In addition, it is necessary to examine the graphite coal - it could well have been worn off. If the cover is worn out, when its surface is cracked or covered with soot, it is better to replace the cover; it cannot be repaired. The same should be done with graphite coal. Attention! All wiring must be well fixed, because if it comes into contact with other components, its insulation will wear out very quickly. A short circuit can occur due to working fluids getting into the wiring. Therefore, when diagnosing the condition of the ignition system, you should pay special attention to the condition of the wiring. If you find moisture on them, you should definitely wipe it off, because this may well be the reason for poor engine starting. If scratches or other mechanical damage are found on the wiring, it must be replaced. If this is not possible yet, you should wrap problem areas with electrical tape. The ignition coil is checked with an ohmmeter. The resistance must be within the specified range, otherwise the coil will have to be replaced. It is highly not recommended to repair the ignition switch on your own. You can only check the contacts and clean them if oxidation is detected.

It is also worth thinking about the switch, because breakdowns in this unit are quite often the cause of incorrect operation of the ignition coils. The switch is checked with a portable lamp. This is done as follows: the wire that comes from the switch terminal is disconnected from the coil, and then its end is connected to the carrier. The other carrying wire is connected to the coil terminal. Then the ignition is turned on and the car starts using the starter. To do this, the crankshaft will have to be rotated a couple of times. If the light in the carrier lights up continuously, it means that the switch is indeed faulty. Then the problem can only be solved by replacing it. It may also happen that all the wiring is working properly, but the pulses still do not arrive at the switch. Most likely, the contactless sensor is faulty here. It is checked with a voltmeter. This is done as follows: with the ignition off, they begin to carefully turn the crankshaft. In this case, you need to monitor the devices. If the sensor is working properly, then their readings will change sharply. If this does not happen, it can be stated that the sensor is faulty, then it must be replaced. Spark plugs are checked with a “spark”. To do this, you need to remove the wire from the spark plug and bring its end to the ground at a distance of 5-6 mm. After this, you should rotate the crankshaft and look at the gap. If a spark is visible, it means that the system itself is working, and all that remains is to change or clean the spark plugs. During this procedure, it will not be possible to do without an assistant who will have to turn the crankshaft. In this way, the distribution system covers can also be checked. The central wire is disconnected from it, and its end is brought to ground, leaving a gap of 5-6 mm. In this case, you also need to rotate the crankshaft. When a strong spark appears, it can be stated that the circuit is operating normally, and the problem may be in the cover or rotor. It is no longer possible to repair the rotor; it can only be replaced. But if the resistor burns out, the problem can be completely solved with a piece of wire. You can use aluminum and copper wire. A jumper is made from it, which is inserted between the contacts of the router. Of course, this measure is temporary, and you should resort to it only when it is not possible to resolve the issue by installing a full-fledged resistor. For example, this can happen while driving. Do not forget also that a piece of inserted wire causes radio interference, which can spread not only in the cabin, but also near it. The reason for the lack of a spark may also be poor contact of the breaker. Poor contact is quite often the cause of cylinder failure. When checking the contacts, you need to ensure that they are in close contact with each other. Any contamination of the contacts with rust or carbon deposits will certainly reduce the tangent area, and this will certainly cause a complete loss of contact. Sometimes the contacts need to be cleaned non-aggressively. A needle file is used for this. You can clean the contacts with a rag. After cleaning the contacts, rotate the crankshaft until they are completely closed. If any contact does not fit tightly, you need to bend its stand. As you can see, a variety of breakdowns in the ignition system can be eliminated on your own. But if you do not feel completely confident in yourself, then it is better to seek help from specialists who will do everything professionally. Video about checking the ignition system:

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