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IT'S common to observe in some candles the occurrence of a stain on the insulator of the candle. Many repairmen think that this stain is due to exhaust fumes from the engine. In fact, if we have an exhaust of gases from the engine, we will have an extremely loud and characteristic noise of exhaust gases.
A stain on insulator is known as stain corona, when high voltage passes through the spark plug, an electric field is generated around the spark plug wires and the spark plug itself. Oil and fuel vapors that are in the engine compartment are attracted for this field to the insulator of the candle forming the mancha.
We remind you that the corona stain does not affect the functioning of the spark plug.
Spark plugs are developed specifically for each type of engine. When we install an overfeed system (turbo or mechanical compressors) we are changing the engine's original operating conditions, so the original spark plug will not meet the new operating conditions.
When installing a turbo compressor, we are increasing the volumetric efficiency of the engine, therefore generating more heat in the combustion chamber and making it difficult for the spark plug to spark due to an increase in the internal pressure of the combustion chamber.
Thus, it is necessary to apply a spark plug with better ignition and thermal degree suitable for the engine. In order to determine the thermal degree of a spark plug, it is necessary to measure the temperature of the ignition tip of the same, in various situations of engine operation, however these tests and trials can only be carried out with appropriate equipment.
So there is no way to indicate a spark plug for an engine that has been modified. In these cases we must rely on the experience and knowledge of our preparer.
P22. How should I maintain spark plugs on new turbo engines?
In turbo vehicles, it is characterized by the use of a turbine that generates a positive pressure in the intake manifold, this characteristic allows a better performance of the engine. And higher combustion chamber pressures. So spark plugs suffer a lot in these applications. Ignition system maintenance must be more careful in these applications to avoid engine damage.
The ignition cables are produced in high quality polymers, but with heating and with time, this rubber dries out and generates loss of electrical insulation. We must replace the ignition cables every 3 years or 60,000 km. In this way we guarantee the perfect functioning of the ignition system.
To measure the resistance of NGK cables, we must use a multimeter on the resistance scale at 20 KΩ. Resistance may vary by cable model.
Basically the sensor test is based on the heater resistance measurement (heater), at room temperature its resistance varies from 2 to 14Ω its resistance is very low, it should be measured at room temperature and with a good quality multimeter. We must also measure the heater power which can be constant battery voltage or a PWM signal depending on the generation of the injection system. We must measure the sensor grounding and the signal generated by the sensor, the signal is only generated with the probe heated (above 350°C)
We can test the glow plug in a few ways, the most common is to measure the resistance of the glow plug, its resistance is up to 5Ω, but the soot and residue accumulated in the glow plug can make it difficult to measure the resistance.
We can measure the supply current, it is a very effective test, with the help of an amperometric pliers we measure the current that passes through the glow plug. We must note whether it is connected in series or parallel. Another test that we can do is with the use of an infrared thermometer, with the engine cold, we check if the spark plugs heat up when we activate the system. NGK has training videos where we demonstrate how to test the glow plug, check the website www.ngkntk.com.br.
You vehicles converted to CNG require a higher voltage from the ignition system for the formation of the spark in the spark plug, this is due to the characteristics of the CNG fuel, therefore it is essential to use high quality products. Using the wire and NGK spark plugs together, which have a high insulation capacity, it is not necessary to reduce the gap between the spark plug electrodes.
There are cases where the kit installed is not suitable for the vehicle or is not is with all components, the kit is incomplete. In these cases, the Back Fire which is the overflow in the intake manifold or flashback in the intake manifold.
Many mechanics try to solve the problem of Back Fire reducing the gap between spark plug electrodes. This practice is not recommended as it may alter engine operation on original fuel as well as engine emission levels. vehicle. 5th generation gas equipment has better performance and greater regulation possibilities. The correct maintenance of the gas kit must also be observed.
Broadband sensors have a controller chip, normally this chip is inside the injection module. When changing brands, two problems can occur. The first the sensor may just not work. The second problem is that the sensor current curve can be different from the original sensor, generating a different margin of error than the vehicle calibration. In this case the injection system will work incorrectly.
We must always follow the NTK application table.
For each glow plug dimensional there is a specific tightening torque, consult NGK through the website www.ngkntk.com.br.
– Supply voltage;
– Grounding;
– Power supply;
– Dwell time;
– Command signal;
– Coil return signal.
The charring of a candle occurs when coal (unburned fuel) accumulates on the ignitable tip of the candle. Coal is a conductor of electrical energy, so a carbonized spark plug will suffer insulation loss causing misfire.
As we increase engine RPM and load, we increase the temperature at the tip of the spark plug. When the temperature of the spark plug tip exceeds 450° we enter a temperature range that we call self-cleaning the spark plug. Where the candle itself burns all the coal residues from the igniter tip.
It should be noted that fuels such as ethanol (alcohol) and CNG do not generate carbonization residues. This is due to a characteristic of the fuel that has smaller carbon chains.
Main factors that facilitate the carbonization of a candle:
– Application of a colder candle than indicated;
– Fuel mixture too rich;
– Engine burning oil;
– Lack of thermostatic valve, engine running cold;
– Use of vehicles at low rotations or low speeds for a long time;
– Delayed ignition point;
– Gap between electrodes too close;
– Low cylinder compression;
– Poor quality fuel;
– Injection problems;
The air surrounding the cable is ionized by the passage of electric current. In low-light environments it is common to see lightning around the wire. This is not leakage current and does not cause malfunctions.
It is the charging time of the coils, that is, the time in which they are energized, accumulating electrical charge. This energization causes a natural heating of the coils.
Flash over is the passage of electric current through the outside of the spark plug. This current flow generates vertical marks on the ignition wires and spark plugs. In these cases we have to replace spark plugs and wires simultaneously.
O flash over is the passage of electric current between the plug terminal pin and the metallic bonnet passing between the plug insulator and the ignition cable. Usually flash over occurs when the voltage of scintillation between the electrodes is very high, making it easier for a spark to occur between the terminal pin and the metallic castle.
When flash over occurs, we can see a characteristic mark on the spark plug insulator and on the ignition cable.
Once the flash over has been identified, we must simultaneously replace the spark plugs and ignition cables, if we replace only one of the parts, the new part will be damaged by the old part and the defect will return in a short time.
Some factors that favor the occurrence of flash over:
– Excessive wear of spark plugs;
– Very lean fuel air mixture;
– Dirt between the spark plug insulator and the ignition cable;
– Ignition cables loose in the spark plug insulator;
Current leakage is when an ignition cable loses electrical insulation and allows the high voltage generated by the coil to escape through the cable. As the high voltage does not reach the spark plug, the vehicle fails when this occurs.
Spark plug overheating occurs when the temperature of the spark plug tip exceeds 850°C for gasoline powered vehicles or 700°C for ethanol powered vehicles.
We can recognize that a candle has overheated by examining the spark plug tip. When the metallic castle is darkened, the insulator tip is white with granules, it is a sign that overheating has occurred. There are extreme cases where the central and lateral electrode fusion can occur, and the electrodes may even disappear completely.
Overheating can cause pre-ignition. That is an abnormal burning condition. Where we have a hot spot in the combustion chamber, when the fuel-air mixture comes in contact with this spot the mixture ignites before the spark of the spark plug. This burning condition can cause several damages to the vehicle's engine.
Main factors that can cause the spark plug to overheat:
– Warmer spark plug than indicated for the vehicle;
– Early ignition point;
– Lean fuel air mixture;
– Use of poor quality fuel;
– Lack of tightening torque on the spark plug;
– Deformation in the castle due to excess torque;
– Installation of objects between the spark plug and the engine head (mechanical tappets; helical threads, etc);
– Very high compression ratio;
– Excessive turbo pressure;
– Cooling system problems;
– Recalibration of injection systems;
The conventional oxygen sensor only informs you if the mixture is rich or lean. In broadband sensors, in addition to identifying whether the mixture is rich or lean, we are able to quantify how rich or poor it is and also whether we are in λ=1. The great advantage of this system is that we can better adjust the air/fuel mixture. Another great advantage is that with it we can measure very rich mixtures and very poor mixtures.
It is a signal that the coil module sends to the injection module, its function is to indicate to the module that the ignition coil has tripped. In some vehicles the lack of this signal causes a component protection strategy where the injection module can cut the supply to the injectors to protect the catalytic converter.
They are candles that have a special technology, where the side electrode has a position inside the combustion chamber, the opening between the electrodes must be positioned for the region of better flow of the combustion chamber. This ensures better burning of the air-fuel mixture. In some cases, the application of a torque outside the specified range may cause fault codes linked to combustion failure to appear. Consult your vehicle manufacturer to verify the specified spark plug tightening torque.
During engine operation, the combustion process of the air/fuel mixture occurs, this process generates heat, part of it is dissipated by engine components, such as block, cylinder head, pistons and valves, another part is transferred to the spark plug, and part is expelled from the engine exhaust system. The spark plug dissipates heat through its insulator and from the spark plug insulator to the thread, passing from the plug thread to the cylinder head, and from the cylinder head to the cooling system, that is, engine cooling.
The thermal degree is the ability of the candle to dissipate heat. In a hot candle the heat dissipation will be slower. In a cold candle the heat dissipation will be faster.
As engines generate different thermal loads, each type of engine has a spark plug with a specific thermal degree.
The determination of the thermal degree is carried out through measuring instruments that are installed in an engine, which in turn is coupled to an engine dynamometer.
With the use of a thermometric plug, the temperature of the spark plug tip inside the engine's combustion chamber is checked. This measurement is performed to identify the most critical condition of the engine, tests are carried out on all engine revolutions and cylinders. The ideal spark plug temperature is 450ºC to 850ºC for gasoline vehicles and a maximum of 700ºC for ethanol. After determining the thermal degree, thermal overload tests are carried out to identify detonation phenomena.
Due to the existence of several types of spark plugs with different thermal degrees, it is very important that the applicator checks the correct spark plug code in the NGK application table or in your vehicle's manual, in this way you will be guaranteeing that you are using a product that was developed , tested and approved for your vehicle.
A NGK candle coding is very important, because in addition to demonstrating the main characteristics of the candle, it identifies the NGK candle worldwide.
In general, we will have a pre-catalyst probe and a post-catalyst probe, this is due to a few reasons:
– Length of wire;
– Connector type;
– Type of heater;
– Generation of the sensor element.
Through the appearance of the spark plug tip we can assess the wear and burning conditions of the spark plug.
Very worn candles indicate the need for replacement.
Spark plugs with excess residue can indicate an abnormal engine running condition or use of poor quality fuel.
The spark plug is also an important means of diagnosing the condition of the engine. Through the analysis of the ignitable tip of the spark plug we can also have a good reference of the state of the combustion chamber. Since the spark plug is the only part that is inside the combustion chamber it is easy to remove and install.
NGK provides in its application table an engine fault diagnosis poster, where through the analysis of the spark plug tip we can diagnose various malfunctions that affect the spark plug.
P9. What is the function of insulator corrugations?
The function of the corrugations in the spark plug insulator is to increase the distance between the spark plug terminal pin and the metallic bonnet, without increasing the total length of the spark plug, thus making it difficult for flash over to occur between the spark plug and the ignition wire.
We can notice that some candle designs do not have corrugations, in these cases the candle insulator is longer and they use special materials in their composition.
As well as the spark plugs, the cables also have resistance, the resistance has the function of attenuating the interference generated by the ignition system. In this way we guarantee the perfect functioning of the electronic systems of current vehicles.
The use of cables without resistance can generate interference and deficiencies in electronic systems.
The main function is to verify the correct functioning of the catalytic converter, when there are efficiency problems or lack of the catalytic converter, it will be indicated to the system. In some injection systems the signal from the second sensor can also be used to verify that the first sensor is working correctly and fine-tune the injection system.
For coils using ignition cables we must inspect the high voltage outputs for signs of flash over. For pen-type coils, we must examine the spark plug connectors.
This practice should never be carried out, there is a serious risk of accidents due to high temperature, very fast heating time and very high electrical current. In models that are controlled by a PWM signal, the glow plug will burn out.
These products can chemically attack the ignition cables and cause oxidation of the cables and other engine components. They are electrical conductors and can confuse the diagnosis by making corona current more visible.
With the entry of electronics on board vehicles, NGK developed in the late 70's the resistive spark plugs, which have a ceramic resistor that aims to attenuate the electromagnetic interference caused by the ignition system.
This interference is extremely harmful to vehicle electronic systems such as:
– Electronic fuel injection;
– Sound system;
– Anti-theft system (alarms, blockadores and trackers);
– Automatic transmission with electronic control;
– Electronic traction and stability control;
– ABS and Air Bag systems;
– CAN network;
– Air conditioning with electronic control;
Most resistive spark plugs have a resistance qwhich can vary from 3 to 7.5 kΩ, from 1 to 2 kΩ for some oldthose of Volkswagen, Audi, Seat e Skoda, 10KΩ para Kia e Hyundai.
We must be careful when we make changes to old cars. These vehicles have low capacity ignition systems and if we install spark plugs and resistive cables due to the use of electronic equipment, we must upgrade the ignition system.
The use of resistive plugs has nothing to do with the lifespan of the plug, that is, it does not affect its durability.
NGK spark plugs meet the most stringent requirements of vehicle manufacturers in terms of performance, technology and durability. Making available to the market the most modern technology developed for spark plugs.
1. It has a “wide thermal range”.
NGK spark plugs have copper embedded in the center electrode. This feature guarantees excellent heat exchange, expanding the working thermal range of NGK spark plugs. Superiorly resisting heating as well as carbonization.
This is due to the catalyst effect, the catalisworship keeps the oxygen level more stable, in this way the probe signal will vary little, becoming a more stable signal.
The main reasons for coil cracks are:
– Excessive heating of the coil;
– Excessive heating of the engine or engine compartment;
– Coil body twist;
– Excessive engine vibration.
Oxygen sensors are manufactured to meet the environmental pollution regulations in force at the time of their manufacture. Therefore, its operating characteristics depend on the vehicle. The main characteristics are heater power, heating time and probe heater supply voltage.
To identify the correct oxygen sensor for your vehicle refer to the NGK table, app or App.
Each coil has been designed to work with a maximum voltage, supply current and Dwell specific teams. It is not advisable to make adjustments to ignition coils, such a practice can lead to the coil overheating and burning out.
Glow plugs have generations of development and must be applied according to the vehicle's system. The power, temperature, warm-up time and after-heating function are defined according to the engine's cold start system.
When installing a spark plug with a directional side electrode, there is a deformation of the gasket, sealing washer. Thus, when removing a spark plug that has already been installed, there is no way to guarantee the perfect direction of the side electrode in the combustion chamber. It is recommended to replace the spark plug with each installation.
The lifespan of a glow plug is linked to the engine starting system warm-up cycles. As the set of glow plugs went through the same work cycle, it is recommended to change the set.
The main reason for shortening the life of a coil is the use of very worn spark plugs. Other factors that also affect its lifespan are power supply voltage out of specification, ground fault, too high supply current and Dwell team out of specification. These problems can cause the coils to overheat and cause damage to the coils.
Each engine manufacturer has a technology and criteria for engine development. With that we have the most different types of designs and dimensions of glow plugs. To facilitate the consultation and correct application of the product, NGK makes available on its website: www.mgkntk.com.br a quick consultation, there you can also download the electronic catalog and in the app stores you can download the APP for IOS and Android.
– Measure the heater resistance, it must be measured at room temperature, its value varies from 2 to 14Ω.
– Measure the heater supply voltage (on the white wires), it can be of the constant supply type or with variable supply (PWM).
– Signal generated by the sensor.
Both voltage and signal must be measured with an oscilloscope.
The coils with coupled ignition module, the entire high current circuit is incorporated into the ignition coil, that is, it has its power supply and receives a command signal from the injection module. As for coils without ignition module, the high current circuit is incorporated into the injection module or in a separate module. This circuit will control the ignition coil.
The SC line cables have resistance built into the wire that is produced with a nickel-chromium alloy, that is, the resistance value of the cable depends on the length of the wire, its resistance is 7.5 KΩ per meter. As for ST type cables, the resistance is at the terminals, on the spark plug side, 5 KΩ and on the coil terminal side, 1 KΩ, that is, the resistance is the same for all wires in the cable set. The type of yarn used depends on the specification of each project.
Basically the current oxygen sensors are made of zirconium dioxide ceramic, what changes between a thimble and planar type is the shape of the sensor element. NTK sensors have a thimble-like shape that has a larger area of contact with the exhaust gases, offering excellent durability. They also offer excellent mechanical and thermal shock resistance. Its high performance heater offers fast heating, reducing pollutant emissions, contributing to the environment and reducing consumption.
Diesel engines have evolved a lot over time, the main focus of evolution is the issue of pollutant emissions. One of the most critical phases of a motor is the start and cold phase of this motor. NGK glow plugs were developed to meet all the needs of these engines in these conditions.
Providing energy in the form of heat to facilitate engine starting and keeping it warm while the engine warms up to reduce pollutant gas emissions and prevent malfunctions.
The use of individual coils has a great advantage over coils that supply multiple cylinders. As the coil drive is more spaced, this generates less stress on the coil, increasing its durability.
NTK sensors have a very long lifespan, over 80,000 km, we always recommend an annual inspection or every 30,000 km or whichever comes first. Factors such as a very rich mixture, engine burning oil and use of poor quality fuel can significantly reduce the life of a sensor.
The lifespan of a glow plug can vary greatly depending on the number of cold start system trips. The technology applied in the most modern engines has greatly increased the useful life of glow plugs. Always consult your engine manufacturer's manual and recommendations.
The function of corrugações in the spark plug insulator, it is necessary to increase the distance between the spark plug terminal pin and the metallic bonnet, without increasing the total length of the spark plug, in this way we make it difficult for a flash over to occur between the spark plug and the ignition cable.
We can notice that some candle designs do not have corrugações, in these cases the spark plug insulator is longer and use special materials in their composition.
The spark plug is located in the cylinder head of vehicles. Its main function is to conduct the electric current generated in the transformer to the combustion chamber, and transform it into a high-voltage electric spark, which will start combustion, that is, the burning of the air/fuel mixture.
Despite its simple appearance, the spark plug is a highly complex part, composed of a series of internal components that require the application of highly sophisticated technology for its design, since its perfect performance is directly linked to the engine's performance, the of fuel consumption, the greater or lesser load of pollutants in the gases expelled by the exhaust.
Spark plugs are developed specifically for each type of engine. Therefore, for each vehicle we have a specific spark plug, we must not change the spark plug specification that was developed together with your vehicle's manufacturer.
The customer can consult the spark plug application in their vehicle manual or through the NGK application table.
NGK provides a series of facilities for our customers. On our website you can make a quick consultation of the application, you can also choose to download an electronic catalog to your computer, this catalog can be easily updated on the internet. For those who prefer, there is an option to download the electronic catalog in PDF. In your App store or Play store you can download a free application for your cell phone and have a quick, easy to use and always updated tool on your cell phone.
To correctly use the NGK application table, we must have some basic vehicle information such as:
* The proper spark plug for the vehicle mentioned above 
developed in the 1980s to meet a need for automakers to comply with pollutant emissions laws that become increasingly strict over the years. years old.
Due to its unique configuration (central electrode with "V" cut and concave side electrode. This spark plug has a great advantage, because its spark occurs on the sides of the electrodes increasing the energy of the front of the flame, which provides a better burning of the fuel. also reducing the emission of polluting gases.
The electrode configuration provides a greater effects of spikes, thus reducing the tension required for the scintillation of the candle. Another great advantage of this spark plug is in the use of fuels such as CNG, where due to the use of leaner mixtures we require higher voltages for the scintillation. The Green candle presents excellent results in the use of this fuel.
Other advantages of using the Green candle Plug are:
– Resistive type spark plugs, avoiding interference in electronic systems, in some markets there are conventional type Green spark plugs, without internal resistance;
– Improved engine performance;
– Faster departures, even on cold days;
– Enables the use of poorer air/fuel mixtures;
– Excellent performance in gas powered vehicles (CNG);
– Provides more stable idle speed;
We can identify the Green candles through their “V” cut in the center electrode and concave side electrode, which are the main characteristics of this candle.
– 2 white wires from the heater;
– 1 gray wire from the probe negative;
– 1 Black probe signal wire.
The wire colors depend on the standard of each sensor manufacturer.
The spark plug is a component of natural wear, that is, as the engine runs, the spark plug wears out.
Who sets the mileage for changing the spark plug is the vehicle assembler within the specifications of each project. During the development of the vehicle, several durability tests are carried out, based on these tests, the exchange mileage is established.
The automakers guide in their manuals that in the condition of severe use of the vehicle, the interval between maintenance must be reduced by half, that is, if an automaker establishes a period of changing the spark plug every 20,000 km in the condition of severe use, the change must be performed every 10,000 km.
Severe use conditions are considered:
– Use of the vehicle in heavy traffic (which is frequent in large cities);
– Use on short journeys and with frequent stops;
– Periods of long inactivity of the vehicle;
– Use of the vehicle as a taxi, ambulance, delivery vehicles, driving school, patrols and the like;
For engines using platinum and iridium spark plugs as original equipment, the severe use rule also applies. So we must cut the exchange km according to the conditions of use of the vehicle.
For cases where we do not know when the last spark plug replacement took place, NGK recommends that the repairman remove the spark plugs for inspection.
The use of worn spark plugs can cause damage to the ignition system,consumption, increased vehicle emission levels and difficulty starting.
All NGK spark plug packages have the recommendations for installing spark plugs in the vehicle. We recommend that the spark plugs be installed by a qualified technician.
The first item that we must observe is whether the spark plug application is correct for the vehicle, for this we just need to consult the NGK application table or the automaker's manual.
Before installing the spark plugs, we must examine the gap between electrodes, all NGK spark plugs leave the factory calibrated, however in the transport and handling of the spark plugs until installation there may be some change in the gap. For Platinum and Iridium candles, we must not apply force directly to the electrodes of the candle, this practice can damage the product.
We must install the spark plug by hand to ensure perfect alignment between the spark plug thread and the engine head.
We have to take special care with the tightening torque, NGK provides the torque table on its packaging. Below we can see the torque table, to apply the torque we must have a calibrated torquemeter.
We can also apply angular torque, where we thread the spark plug by hand until it touches the head and then apply the torque:
Spark plug tightness is very important, because the plug dissipates heat from the tip. igniferous through the spark plug insulator and the insulator to the metal bonnet and from the bonnet to the engine head. The lack of torque affects this thermal exchange and can cause severe damage to the motor.
Another fault that is linked to the tightening of the spark plug is the rupture of the spark plug thread or the groove due to excess torque. When we apply excessive torque, the thread can break during tightening or during the loosening process. In both cases we can cause damage to the engine.
The tilt of the key during the tightening process can cause cracks in the ceramic insulator and cause misfires.
The spark plug is developed for each type of engine, for the original conditions of the vehicle. With the adaptation of CNG in a vehicle, we are changing its original characteristics.
Vehicles powered by CNG have the characteristic of working with a leaner mixture than the original and require a higher voltage for sparking, there is an increase of around 5 K volts depending on the generation of the gas kit and regulation.
If the CNG kit is well dimensioned and well installed, the original spark plug should work normally. Many installers recommend replacing the original spark plug with a spark plug with better ignition such as Green, Platinum and Iridium spark plugs. G-Power Platinum and Iridium IX spark plugs offer excellent performance in CNG. This option is valid when there is an optional candlestick recommendation in the NGK application tables.
The use of CNG is considered a severe application, therefore the spark plug change recommendation should be reduced by half of the original recommendation.
There are motors that work with a voltage of 24 volts. Others work with a voltage of 12 volts. And in the most modern applications we work with a PWM signal (pulse width modulation), that is, a square wave of the on and off type, where the injection module will control the time that the pulse remains on and off.
In these systems it is common to see a medium voltage marking on the glow plug.
Diesel engines that are used in passenger vehicles, SUV's, trucks and small machines are considered small engines. To avoid noise, vibrations and harshness in the engine operation, they work with a lower compression ratio when compared to larger engines. Due to this characteristic, these engines normally use glow plugs. There are also heating systems for the air being admitted by the engine, these systems also aim to facilitate starting and reduce emissions of polluting gases.
Automotive scanners have a graphic function where we can check the signal generated by the sensors. What we must observe is that the signal generated by the sensor is sent to the injection module, there this signal is processed and sent to the scanner through a diagnostic socket. In the scanner we observe a processed signal and not a real signal. When observing a signal in the automotive scanner, we must compare it with the signal in the sensor, in this way we will know if what we are observing is the sensor signal or a strategy of the injection module.
The use of solvents causes the ignition cables to dry out, reducing their useful life. There are specific products that do not harm rubber. The use of high pressure washers can cause water to seep in and cause malfunctions.