Common Symptoms of the Faulty Spark Plug(s)

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The Spark Plugs in a gas powered vehicle are fundamental components of the ignition system, the Spark Plugs use an electrical current of up to 80,000 volts in some applications to cross the air gap between two electrodes and produce a spark that ignites the air-fuel mixture in the combustion chamber. This powers the engine and enables the vehicle to operate.

If the Spark Plugs malfunction or are damaged, it severely affects the engine's operation. This article will help you recognize the signs of faulty Spark Plug(s) and understand what causes them to fail.

What Causes Spark Plug Failures?

Carbon deposits, Erosion, Oil and Fuel Fouling: Over time, buildup of carbon and grime as well as erosion or damage to electrodes interferes with the spark, leading to misfires, rough idling, and reduced performance. Additionally, oil and fuel fouling can lead to poor spark generation, misfires, and rough idling.

Electrical issues: Loose or low quality wire connections cause problems or restrictions in the voltage sent to the spark plugs.

Overheating: Spark plugs can overheat if they are subjected to high engine temperatures or if the engine runs lean. This can cause electrode erosion, insulator damage, and pre-ignition issues.

Incorrect Installation: Improper installation or handling of spark plugs, such as incorrect torque specifications, cross-threading, and dropping or bumping them can damage the spark plug threads, insulator, or electrodes.

Common Symptoms of the Faulty Spark Plug(s)

Check Engine Light (CEL)/Malfunction Indicator Light (MIL) Illuminates

A malfunctioning spark plug may trigger the vehicle's onboard diagnostics system to illuminate the Malfunction Indicator Light (MIL). The MIL can illuminate for various issues, so it may not necessarily mean the spark plug is the cause. Check the Diagnostic Trouble Code (DTC) connecting an OBD Code Reader or Scan Tool to the Data Link Connector (DLC) port under the dash near the left side of your steering column to determine if the spark plug is your issue.

Engine Misfire

If one or more spark plugs are broken, there is potential for engine misfiring and knocking. This is harmful for various engine components such as the connecting rod, crankshaft, pistons, etc., as they undergo erratic stresses and forces that can cause premature failure of the components. Misfiring engines also increase the pollutants produced, which can damage the catalytic converter.

Rough Idle

When idling, if you hear knocking or irregular sounds from the engine, a spark plug may have failed. Rough idle is a possible indication of spark plug failure.

Poor Fuel Economy

If the air-fuel mixture is left unignited by the spark plug, the fuel simply goes to waste without producing any power, which can eventually result in drastically increased fuel consumption and lowered engine performance.

Lack of acceleration

Malfunctioning spark plugs may not generate a strong enough spark to ignite the air-fuel mixture properly, leading to incomplete combustion or misfire, or disrupt the engine's ignition timing, causing the combustion process to occur at the wrong moment. These issues can result in inefficient power generation and reduced torque output, leading to sluggish acceleration.

Difficulty to Start

Bad spark plugs can be the reason for starting issues and replacing them can lead to easy and quick engine starts. The most obvious sign of spark plug failure is the inability to cold start the vehicle. A delayed spark adversely affects engine idling. This is particularly noticeable after extended periods of idle time. Worn out spark plugs will prevent combustion, and therefore, the engine will not start.

Identify Faulty Spark Plug(s) with the Innova Scan Tool

The Innova Scan Tool is an invaluable diagnostic instrument capable of swiftly pinpointing issues within a vehicle's systems. Specifically, it excels in detecting DTCs linked to Spark Plug(s) damage.

Additionally, you can read the Total Misfire value (Live Data) using the INNOVA 5610 tool to track misfires. The normal operating value of the Total Misfire depends on your vehicle.

Please visit us at innova.com/support or pro.repairsolutions.com/Support for additional information.

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