NGK clarifies the 6 most frequently asked questions of mechanics

Main uncertainties revolve around the duration and cleaning time of the candle, Tests on oxygen sensors and factors affecting coil life

São Paulo, March 2023 - A NGK, Japanese multinational specialist in ignition system, works in favor of the development and quality of the work of mechanics. The company has a Customer Service that allows the customer to clarify doubts with a highly qualified technical team to serve this public.

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In view of the most frequent demands of professionals, NGK clarifies the main doubts it receives daily from mechanics in its communication channels:

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1) What is the carbonization of a candle?

Carbonization of a candle occurs when there is accumulation of coal (unburned fuel) on the flame retardant tip of the item. Coal is a conductor of electrical energy, therefore the charred spark plug will suffer loss of insulation that will cause misfires.

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As engine speed and load increase, the temperature of the candle tip becomes more intense. When the temperature exceeds 450°, Spark plug self-cleaning begins, where the component itself burns all the coal residues from the fireproof tip.

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2) how long does a candle last?

The durability of a sail is defined by the automaker's engineering - This means that it is a requirement established in the design during the development of the vehicle.

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"In our tests, We check if the chosen candle meets this requirement. We observe that when there is a change in the specification, such as the use of special candles Iridium IX and Platinum G-Power, We cannot say what the new durability will be, Because we do not perform the tests within the criteria of the automaker to prove the new life of the item. In this case, it is advisable to maintain the same service life as the original candle.", explains Hiromori Mori, NGK do Brasil Technical Assistance consultant.

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3) What are the main factors that affect the life of a coil?

According to Mori, The main reason for reducing the service life of a coil is the use of very worn spark plugs. Other factors that affect the component are problems in the supply voltage, supply current, Connectors (Bad contact) and vehicle harnesses (short on the whip and water infiltration on the whip), and injection modules (on the command drive). These adversities can lead to overheating and damage to the coils.

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4) What tests can we perform on oxygen sensors?

The main tests are to measure the resistance and supply voltage of the heater, and check the signal generated by the sensor. Both the voltage and the signal must be measured with an oscilloscope - Electrical and electronic signal measuring instrument.

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"When the diagnosis of the failure is not carried out properly, and probe exchange is practiced, The mechanic may believe that the defect is in the new part, leading to lost time in vehicle repair or warranty issues - Return of Service. That is why, It is essential to make the correct diagnosis of the oxygen sensor.", clarifies Mori.

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5) I can change only one glow plug?

The service life of a heating spark plug is linked to the heating cycles of the cold start system of the diesel engine. "How the set of heating candles goes through the same duty cycle, There is a tendency that, when a heating candle burns, the others will present problems soon. In this sense, the indicated is the exchange of the set", inform the expert.

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6) Can I clean the candle?

Candle cleaning is not recommended. If the mechanic finds residues, It is advisable to replace the component. "The metallic castle, where are the thread and hexago, receives a protective bath that can be zinc plated or chromium nickel. That is why, Using steel brush for cleaning can remove the protective bath and expose the metal part to the action of the medium, causing oxidation ", affirms Mori.

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"Beyond the metal castle, The tip of the ceramic insulator has a certain porosity. Fuel waste, oil and contaminants impregnate in the insulator and do not allow its total removal, not being feasible to clean", says the NGK consultant.

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According to Mori, The use of steel brushes can wear down the side and center electrode, causing items to be rounded. "At last, when the candle has noble metal Iridium or Platinum, Mechanical action can damage the central and lateral electrodes. Some candles have directional side electrode - And the automaker does not recommend the reinstallation of these candles."