Failure Diagnosis

Spark Plugs:

For the failure diagnosis of the spark plug we can follow the following roadmap:

– Check out on which cylinder occurs misfire;

– Replace the spark plug of cylinder and check out if the failure exchange the cylinder, if this has not occurred is a sign that the failure is not from the spark plug;

– With the assistance of a megohmmeter, check out the spark plug isolation. Low isolation can be due to carbonization, flooding and cracks on the isolator. In this case replace the spark plugs;

– To conventional spark plugs check out the spark plug continuity, using the megohmmeter, spark plugs without continuity should be replaced.

– For resistive type spark plugs check out the value of the internal resistance of the spark plug that can range from 3 to 7.5 kΩ, for some models of spark plug the resistance ranges from 1 to 2 KΩ. Spark plugs with resistance value outside the specified should be replaced

– Visual analysis:

Through consultation of the NGK engine failures diagnosis newsletter, check out the condition of the spark plugs burning.

– See the training videos:

Video 4 – Voltage required, spark plug wear and preventive maintenance;
Video 6 – Spark plug exchange;

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Ignition cables:

For the failure diagnosis of the ignition cables we can follow the following roadmap:

– Check out the resistance of the ignition cables, you will find the reference values in the NGK recommendations catalog or through the SAC (Customer Support Service) 0800197112.

– Visual analysis:

Visually inspect the ignition cable and check out the NGK do Brasil engine failures diagnosis newsletter regarding damage and handling failures.

– See the training videos:

Video 9 – Cable types and ignition cable testing;
Video 10 – Ignition cable handling;

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Oxygen Sensor:

For the failure diagnosis of the oxygen sensors we can follow the following roadmap:

– Check out the sensor heater resistance, if the resistance value is out of the specified, the sensor should be replaced;

– Check out the power supply of the sensor, if the value is out of the specified see the repair manual of the vehicle;

– Check out the signal generated by the oxygen sensor and the sensor’s response time. Not always a signal out of the specified indicates an oxygen sensor failure, injection system problems interfere directly in the signal generated by the oxygen sensor.

– Visual analysis of oxygen sensor:

Visually inspect the oxygen sensor regarding damage and handling failures. See the NGKNTK recommendations catalog.

Inspect the protective pipe appearance, accumulation of soot or sediment may indicate an irregular condition of burning in the engine.

– See the training video:

Video 15 – Analysis of the signal generated by the sensor.

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