Diagnosis of Faults

Appearance of the candle:

Coal waste deposits (black color) at the tip of the candle, is one of the main problems encountered with spark plugs.. Coal is formed by unburned or excessively injected fuel. Fuels like ethanol (alcohol) and CNG (vehicle gas) do not generate coal residue. Waste is common with the use of gasoline.

Problems: Coal is a conductor of electrical energy and causes loss of spark plug insulation, generating misfire.

difficulty in starting, mainly with a cold engine;

Increased fuel consumption;

Misfires;

Increased levels of polluting gases;

black smoke in exhaust;

Black waste in exhaust, as a dry feature.

Causes:

1. 1. rich mix;
2. 2. Lack of tightness in fuel injectors;
3. 3. Canister Bleed Valve Locked Open;
4. 4. Canister saturated with liquid fuel;
5. 5. Sensores MAP, MAF, engine temperature, air temperature and oxygen sensor in poor condition;
6. 6. Fuel line pressure too high;
7. 7. Use of unspecified injectors for vehicle or other fuel (flex);
8. 8. Application of electro erosion on injectors or corrosion due to the use of poor quality fuel;
9. 9. Lack of thermostatic valve;
10. 10. Use of poor quality fuel;
11. 11. Application of incorrect spark plugs or with incorrect clearance;

Solutions:

Para as causas de 1 a 8, Fix Injection System Problems;

For Cause 4, in addition to fixing the canister problem, fuel the vehicle until the pump turns off automatically;

Para a causa 9, fix cooling system problems;

Para a causa 10, use good quality fuel;

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Coal residue at the tip of the candle, but with a damp appearance (wet).

Problems:

Loss of spark plug insulation

difficulty starting;

Misfire;

Lubricating oil consumption;

Causes:

1. 1. Valve guide clearance above specified;
2. 2. Valve guide retainer lacking tightness,
3. 3. wear rings, excessive clearance between rings, ring break.
4. 4. lack of honour, scratched or oval cylinder;
5. 5. Excessive pressure in oil pan;
6. 6. Clearance in turbine shaft;
7. 7. Lubricating oil contamination;
8. 8. Oil level above specified;
9. 9. Using oil with incorrect viscosity;
10. 10. Use of poor quality or contaminated fuel;

Solutions:

Para as causas de 1 a 8, correct the problems that are increasing the consumption of lubricating oil;

Para a causa 9, use specific lubricant for the engine;

Para a causa 10, use good quality fuel;

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle

Reddish coloration at the tip of the ceramic insulator, may have flashover marks (misfires).

Problems:

difficulty in starting;

Acceleration Resume Failed;

Increased fuel consumption;

Increased levels of pollutant emissions;

Causes:

1. 1. Use of poor quality fuel;
2. 2. Use of iron oxide in fuel;

Solutions:

Para as causas 1 e 2, use good quality fuel.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance:

Corrosion in the area of ​​the spark plug thread and/or internal part of the metallic castle.

Problems:

Locking the spark plug thread in the head;

Damage to the head thread;

Difficulty in removing the candle;

Disruption of the candle's castle in the removal;

Misfires.

Causes:

1. 1. Use of wire brush to clean spark plug thread, removing the protective bath from the metal part;
2. 2. Infiltration of coolant into the combustion chamber;
3. 3. fuel usage (ethanol) shoddy.

Solutions:

For Cause 1, do not use abrasive materials to clean spark plugs;

For Cause 2, check for possible leakage of coolant into the combustion chamber;

For Cause 3, use good quality fuel.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance:

Deformation or misalignment of the central and lateral electrode;

Breaking the ceramic insulator;

Kneading or deformation of the metal castle.

Problems:

malfunction;

Cylinder compression loss.

Causes:

1. 1. Breakage of parts that make up the combustion chamber;
2. 2. excessive heat (heat stress) in the combustion chamber;
3. 3. Material fatigue of moving combustion chamber components;
4. 4. Abnormal combustion phenomena such as pre-ignition and detonation;
5. 5. Mix depletion;
6. 6. Use of poor quality fuel;

Solutions:

For Cause 1, check and correct any engine wear problems;

For Cause 2, check the cooling system and any heat exchange problems;

For Cause 3, check moving engine components for wear and alignment., avoiding the reuse of wear components;

For Cause 4, check for hot spots in the combustion chamber, residues and/or deformation or impact points;

Para causa 5, in the case of turbo engines or with high compression ratio, check air/fuel mixture stoichiometry in all rpm ranges varying engine load;

For Cause 6, use good quality fuel;

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Spark plug tip soaked in fuel or lubricating oil.

Problems:

Misfire;

difficulty in starting;

Irregular slow gait;

Increased fuel consumption;

Increased emissions.

Causes:

1. 1.Vazamento de óleo na tampa de válvulas e acumulando no duto da instalação da vela;
2. 2.Falta de estanqueidade de injetores ou com vazão muito acima do especificado;
3. 3.Tempo de injeção muito alto;
4. 4.Folga entre eletrodos da vela muito fechada;
5. 5.Isolador da vela de ignição trincado na instalação;

Solutions:

For Cause 1, correct any leaks in the valve cover;

For causes 2 and 3, fix the problems related to the injection system;

For Cause 4, check gaps between spark plug electrodes before installing;

For Cause 5, replace the spark plug using a suitable tool and applying the specific tightening torque.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Deformation of the metallic castle (stretching) the castle may or may not break. In cases where there is no complete breakage of the metallic castle, the insulator may loosen due to the loss of pressure in the sealing washer.

Problems:

Breakage of the metallic castle in the installation of the candle.

Breakage of the metallic castle when the candle is uninstalled.

Ceramic insulator release.

Causes:

1. 1. Torque application above specified.
2. 2. Oxidation between the cylinder head thread and spark plug.

Solutions:

For Cause 1, apply the correct tightening torque as per the motor manufacturer's specification or NGK torque table.

For Cause 2, do not clean candles using a wire brush, this practice removes the protective bath causing the metal castle to oxidize.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Rounding of central or lateral electrodes, loss of sharp corners in the electrodes and increased clearance between them.

Noble metal candles such as platinum and iridium wear is barely noticed on visual inspection, the electrode has oxidation points and material deposits on the electrodes.

Problems:

Increased sparking voltage;

Difficulty in cold starting;

Acceleration failures and speed resumption;

Damage to the ignition system and reduced useful life of ignition coils;

Misfires using CNG (vehicle gas), back-fire (intake manifold overflow).

Increased levels of pollutant emissions;

Flash-over, high voltage passage on the outside of the spark plug;

Consumption increase;

Causes:

1. 1.Desgaste natural da vela;
2. 2.Final de vida útil.

Solutions:

Para as causas 1 e 2, replace spark plugs according to vehicle maintenance manual, if you don't have, revise as velas anualmente ou a cada 10.000km para automóveis e 3.000 km for motorcycles. Replace if necessary.

For severe use, in heavy traffic situations, frequent matches, etc, replace the spark plug more often;

Use with CNG (vehicle gas) is considered severe use, it is necessary to change more often.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle, cable and coil:

Sail: Dark vertical marks between terminal pin and metal castle, caused by the passage of electric current on the outside of the spark plug.

Cape: Vertical marks on the cable insulation rubber, caused by the passage of electric current.

Coil: Vertical marks on the coil insulation rubber or between the high voltage terminals, caused by the passage of electric current.

Problems:

Misfires, especially at higher engine torque rotations, which can generate overflows in the intake manifold in case of CNG use.

Consumption increase;

Increased levels of pollutant emissions;

Causes:

1. 1. Replacing only one component affected by flashover;
2. 2. Presence of contaminants between the surface of the spark plug and cable or spark plug and ignition coil;
3. 3. lean mixture;
4. 4. Excessive wear of spark plugs;
5. 5. Cable or coil with dry or inelastic rubber terminal;
6. 6. Compression ratio or turbo pressure too high;
7. 7. delayed ignition timing;
8. 8. Incorrect candle application, cables and coil;

Solutions:

For Cause 1, replace candles, cables and coil simultaneously;

For Cause 2, clean your hands, avoiding oil residue, greases and solvents in ignition components;

For Cause 3, check the correct operation of the injection system;

For causes 4 and 5, follow the maintenance plan specified by the engine manufacturer. If you do not have the maintenance plan, the recommendation is to inspect every 10.000km and change every 3 years or 60.000Whichever comes first;

For Cause 6, check compression ratio or turbo pressure, correcting if necessary;

For Cause 7, in CNG systems (gas) and programmable injection system, check the correct ignition timing;

For Cause 8, replace the candles, cables and ignition coil by those specified in the NGK application table.

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Appearance of the candle:

The crack can be visible or not. The visible ones are characterized by a crack in the candle's ceramic insulator. Non-visible can be detected when there is an insulator misalignment or in a high pressure spark test.

Trouble:

Misfire with the new spark plug.

Causes:

1. 1. Spark plug wrench misalignment at installation (incorrect handling);
2. 2. Use of bad or unspecified key;

Solutions:

Para as causas 1 e 2, use proper tools and in good condition, ensuring full coverage of the hexagonal part of the candle and avoiding contact with the ceramic part.

OBS: Due to the difficulty of some specific engines, it is necessary to use a special tool to install the spark plugs.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Yellow to brown stains on the outside of the ceramic insulator near the metal castle.

Trouble:

Does not generate engine problems.

Cause:

With the passage of electric current through the spark plug, an electric field is generated that attracts oil particles, fuels and other volatile products that are suspended in the engine compartment. These particles adhere to the surface of the insulator forming surface stains on the part..

Solutions:

Correct any oil or fuel leaks in the engine;

Avoid the use of volatile solvents in the engine safe.

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Appearance of the candle:

Side electrode breakage in the region above the electrode weld.

Problems:

Misfire;

power loss;

Difficulty starting the engine.

Causes:

1. 1.Vibração anormal no motor;
2. 2.Falta de torque de aperto;
3. 3.Fenômenos de combustão anormal como detonação no motor;
4. 4.Resíduo na câmara de combustão;
5. 5.Combustível de má qualidade.

Solutions:

For Cause 1, check sources of abnormal engine vibration;

For Cause 2, apply the tightening torque recommended in the NGK application table;

For Cause 3, check ignition calibration in case of recalibration of injection systems or use of programmable systems.

For Cause 4, check the presence of residue in the combustion chamber, if necessary, clean the residues in the chamber;

For Cause 5, use good quality fuel.

for all causes, replace spark plugs with those specified in the NGK application chart.

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Appearance of the candle:

Deformation or melting of spark plug electrodes, change in the color of the metallic castle (darkening) and ceramic degradation indicate candle overheating..

Problems:

Misfire;

Engine efficiency loss.

Causes:

1. 1. Cooling System Problems;
2. 2. Very high compression rate;
3. 3. Residue in combustion chamber or hot spots in combustion chamber;
4. 4. Use of helicoil-type build-up thread or filler materials with different heat exchange coefficient on the spark plug thread;
5. 5. Air/lean fuel mixture;
6. 6. Knock sensor damaged or incorrect torque;
7. 7. Excessive spark timing advance;
8. 8. Excessive turbo pressure;
9. 9. High intake air temperature;
10. 10. Obstruction of exhaust system;
11. 11. Low octane fuel usage;
12. 12. Lack of spark plug tightening torque;
13. 13. Elongation of the metallic castle due to excessive torque;
14. 14. Incorrect spark plug application;

Solutions:

For Cause 1, check and fix cooling system problems;

Para as causas de 2 a 4, check and fix engine-related problems;

Para as causas de 5 a 8, check and correct problems related to the injection and turbocharging system;

Para as causas 9 e 10, check and correct problems related to the admission system, turbo heat exchanger (intercooler) and exhaust;

Para a causa 11, use good quality fuel;

Para as causas 12 a 14, apply the spark plug according to the NGK application table with the correct tightening torque.

for all causes, replace spark plugs with those specified in the NGK application chart.

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