Spark Plug Arcing Symptoms, Causes and Solution

Spark plug arcing can alter your driving satisfaction if you fail to fix the fault immediately. It is advisable to rectify such problems immediately before they degenerate into something more severe.

From your car’s rough idling to the other engine inadequacies, such as engine misfire, knocking, poor acceleration, starting issue and bad fuel economy, these spark plug arcing symptoms are easy to identify. However, some of these symptoms are not only peculiar to spark plug arcing in a car.

So, take a moment to carefully read this article to understand how these symptoms occur when your car’s spark plug is arcing and how to rectify the problem.

spark plug arcing

Spark Plug Arcing Symptoms

Virtually every mechanical and electrical malfunction in a car comes with apparent symptoms that help ensure you’re not taken unaware. Hence, it is very vital to pay attention to the following spark plug wire arcing symptoms in case they occur at any point in time in your car.

Unstable idle

Rough idling is a primary sign of a spark plug arcing in a vehicle. If you notice that your car keeps shaking randomly when parked or in neutral, there’s a tendency for that electrical current may be jumping up and down due to the spark plug arcing.

Unstable idling can be frustrating, especially when idling your car in the morning, because you may need to support it with the gas pedal until the spark plug wire defect is rectified.

Engine misfire

The spark plug wires transport electric current from the designated distributor cap to their respective spark plugs.

If the transported current does not reach its destination successfully due to defective spark plug wires, the vehicle’s engine will experience a misfire, further leading to engine backfires. You have a spark plug arcing problem to deal with if you’re experiencing this challenge.

Bad fuel economy

Another symptom of spark plug arcing issues is bad fuel economy. During combustion, the incomplete burning of fuel in each cylinder in your vehicle will eventually result in increased fuel consumption due to the arcing.

This would further lead to increased fuel cost as there’s a need to keep your vehicle running.

Poor acceleration

The spark plugs’ electric current is responsible for igniting the air-fuel mixture within the cylinder, which in turn powers the pistons and driveshaft of the vehicle.

Arcing in the spark plug wires can cause the electric current to become insufficient, reducing the power supply and leading to inadequate driving performance.

In other words, if your vehicle suddenly starts to struggle while accelerating on the road, it could indicate a spark plug defect.

Engine knocking

Besides worn-out rod bearings or piston rings, spark plug wire arcing is another culprit of engine knocking. This is due to the misfire within the cylinders as a result of a weak spark from the plugs.

If you’re currently experiencing this challenge in your vehicle, you should thoroughly inspect the engine compartment to know what the problem is.

Engine start difficulty

Lastly, difficulty in starting your vehicle’s engine is another sign of a spark plug arcing problem. The spark plugs are designed to trigger the spark that ignites the engine’s combustion process.

However, if the voltage supplied by the plugs is insufficient to ignite the process, it may be challenging to start the car. Besides the spark plug arcing issue, there are other problems that can as well result in engine start difficulty.

Causes of Spark Plug Wires Arcing

There are several causes of spark plug wires arcing. Identifying the specific cause of the problem is a primary requirement for providing a remedy to the problem. Some of the most common causes of spark plug arcing include the following.

Improper ground

The Improper ground is one of the foremost and most common reasons why vehicles experience spark plug arcing. This is usually a result of the wires being too loose or too close within a tight location in the engine compartment.

So, electric current can jump from one wire to another or sometimes to a metal part in the engine block. You will certainly experience arcing in the spark plug wire when this happens.

Incorrect installation

Incorrect installation is another cause of spark plugs arcing. If the spark plug wire boot does not fit onto the plug’s end properly, there’s a tendency for the electric current to jump and arc from the wire to another metal part of the engine.

Carbon tracking

Sometimes, dirt and oil can accumulate around the ends of a car’s spark plug wires, resulting wet black spark plugs and impacting the flow of electric current.

So, instead of the current going through the engine from the wire, it may flow from one end of the spark plug’s wire to another. Hence, carbon tracking is another culprit of spark plug arcing.

Can I Mix Spark Plug Wires?

No. You cannot mix your vehicle’s spark plug wires. Doing so can trigger cylinder misfire or poor combustion. These crossed spark plug wires symptoms can further affect your vehicle’s engine performance.

Since the spark plug wires are arranged in a particular order, it would be best to stick to the designated pattern of snugging them onto the plug’s end.

Mixing the wires can be detrimental to your vehicle due to the impact the cross order would have on the engine. In other words, an engine problem is imminent if you decide to mix your car’s spark plug wires.

There’s no point trying to experiment with the order of fixing your car’s spark plug wires. If you’re unsure of the order, kindly consult your owner’s manual to identify the specified arrangement pattern to avoid complications. Or better still, consult an auto mechanic.

How to Stop Spark Plug Wires from Arcing

Fixing a spark plug arcing problem is straightforward once you identify the actual cause of the problem.

So, if you’re currently experiencing a spark plug arcing issue, ensure to fix the problem early enough to avoid unnecessary escalation. Here’s a remedy on how to stop spark plug wires from arcing.

Inspect spark plug wires regularly.

First and foremost, ensure to develop a culture of regularly inspecting your vehicle’s spark plugs and wires. This will enable you to identify any wear and tear that may be impacting the proper functionality of the components.

So, carefully inspect for signs of corrosion or damages that could result in the spark plug wires arcing when in use.

Replace defective spark plug wires.

Once you identify any wear, tear, corrosion, or damage around the spark plug wires, crimp plug wires or replace them at the earliest. Meanwhile, remember to buy the specific spark plug wires recommended by your vehicle’s manufacturer.

You should carefully note the unique characters inputted as signs to distinguish the wires. If it is possible to take the current wire along when buying a new replacement part, kindly do so to avoid confusion.

Fixing Spark Plug Wires Arcing YouTube


Spark plug arcing symptoms are simple to identify. However, the signs may sometimes be confusing because they can also be associated with other vehicle mechanical or electrical problems.

For instance, a clogged air filter, faulty oxygen sensor, and fuel system issues can trigger poor acceleration, a symptom of spark plug wire arcing issues. In other words, it is important to carefully inspect and diagnose the issue before concluding on the exact problem.

Nevertheless, if you’re experiencing any of the symptoms mentioned above in this article, there’s a tendency for the issue to be associated with a faulty spark plug wire. So, verify the exact cause of the problem and fix it as soon as possible.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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