What Are The Symptoms Of Bad Spark Plugs?

A spark plug is a critical piece of automotive equipment despite its miniscule size since it is responsible for igniting the engine. Fuel in the combustion chamber would not be able to ignite without the presence of a spark. Fuel injectors have relied on spark plugs for decades.

But, is there a way to tell whether you need to replace your spark plugs? It’s significantly simpler and less expensive to fix a clogged spark plug in an older vehicle once you know what to look for. In this article, we will be telling you how to check for symptoms of bad spark plugs before they do damage to the other parts of your vehicle.

What is a spark plug?

Spark plugs should be checked on if the engine light comes on and the engine isn’t running as smoothly as it should. Fuel filters, air filters, and motor oil all require regular servicing and maintenance to keep engines working smoothly. Spark plugs are no different. Every engine needs a spark plug. It might do severe damage to your engine if they fail. Spark plugs are a vital part of the ignition system; therefore, it’s essential to understand their role before we look at the symptoms.

An internal combustion engine’s cylinder head houses two electrodes, separated by an air gap, from which a high-tension ignition system discharges a spark to ignite the air-fuel combination.

The spark plug, also known as a sparking plug, is an essential component of an engine’s ignition system. Both the electrodes and the insulator that separates them must be capable of withstanding extremely high temperatures and several thousand volts of electrical stresses.

What are the symptoms of bad spark plugs?

The following are eight symptoms that you may be dealing with a faulty spark plug, so you should be on the lookout for them in future by learning how to identify the problem:

  1. Engine misfires

The most common cause of an engine misfire is a clogged spark plug. An engine misfire occurs when one or more of your engine’s cylinders cannot provide the necessary output. Due to a lack of complete combustion in the cylinder, the engine’s power can be drained. In addition to faulty ignition coil plug caps and poor fuel quality, engine misfires can be caused by various additional factors.

However, a worn-out spark plug is frequently the cause of a misfire. While driving, you’ll notice that the engine slows and then picks up speed. You may hear a popping sound as the engine loses and regains timing. When a car misfires, it shoots unburned fuel out the exhaust, which damages the catalytic converter. Engine misfires can cause a sputtering sound, intense shaking, or an abrupt loss of power in your car’s engine.

  1. Bad fuel economy

Poor fuel economy can be a sign of faulty spark plugs, even if it isn’t evident to the human sight or ear. Your MPG can be reduced by 15% to 30% if your spark plugs are outdated or loose. It isn’t just the cost of replacing a catalytic converter that can be attributed to poorly maintained spark plugs. The combustion chamber can’t properly burn the fuel when the spark plugs aren’t working correctly. 

Gasoline efficiency suffers as a result, as the car is forced to use more fuel to keep running correctly. Consequently, the car owner will note that when their spark plugs are worn out, the engine isn’t the only item that is working overtime. Car owners will spend a lot of money if their car’s plugs are ruined.

  1. Check engine light is blinking

As a result of an engine misfire, the engine control unit (ECU) will often detect this and store a fault code, activating the check engine light. As a result, using an OBD2 scanner to read your car’s trouble codes is a wise decision. 

Although it is possible to forget to check your vehicle’s service schedule, the system is designed to notify you of potential issues. The check engine light should be taken seriously. This is a proactive alert to take action in case of a car accident or a more severe and costly maintenance issue.

The ignition system is the most prevalent reason for the sluggish acceleration in most automobiles. In today’s advanced engines, sensors notify the onboard computer and ignition system when to fire the spark plug. Therefore the problem could be with a defective sensor. However, a worn-out spark plug can be the source of the problem in some cases. The components that make up a spark plug combine to create a spark that is hot enough to ignite an air-fuel mixture. 

  1. Trouble accelerating

These materials wear down with time, which reduces the spark plug’s effectiveness, resulting in a decrease in acceleration. There is a possibility that a broken spark plug is to blame if your car is sluggish or doesn’t accelerate as rapidly as it used to. A mechanic should investigate this problem because it could be caused by various other issues, including defective fuel filters, blocked or dirty gas injectors, and malfunctioning oxygen sensors.

  1. Rough idle

When your spark plugs are working correctly, your engine will run smoothly and steadily. While idle, a fouled spark plug makes your engine seem sluggish. You may also notice the vehicle shaking or vibrating. Unburned fuel might confuse O2 sensors when a misfire happens because of faulty spark plugs. As a result, the oxygen sensor will control the fuel mixture, and you may end up with a lean mixture.

Rough idle and even more cylinder misfires can result from this. Poor spark plugs, as you know, can lead to cylinder misfiring, especially at low RPMs, such as while the engine is idling. If your car’s idle is harsh and sounds like a tractor, you have likely failed spark plugs, as is often the case.

  1. Engine knocking

If you overlook any indications of a broken spark plug, you could be in for a nasty surprise. For example, you might hear an engine knocking, which is a significant problem that will almost certainly lead to a complete engine failure and mechanical damage to critical components such as the piston heads and compression rings. You could lose your car’s cylinder head valves and other essential engine components if you don’t fix the engine knocking problem as soon as possible.

  1. Hard start

Is your car not starting up? When you’re idling, the sound of your engine is scratchy and jerky. It will also cause vibrations in your vehicle. Indicating that one of your car’s cylinders is misfiring while at rest. While a dead battery or a low gas tank may be your initial assumptions, faulty spark plugs could be to blame. 

If your spark plugs fail to generate a spark, your engine will not be able to begin burning fuel. When your car takes longer to get going after a hard start, we’re talking about a hard start. As a general rule, this indicates an issue with the ignition system’s spark plug. If the problem persists, it will lead to ignition issues.

  1. Black exhaust smoke

In addition to producing thick, black exhaust smoke, work-out spark plugs can significantly increase carbon dioxide emissions. You should take your car to a repair if you detect this poor spark plug symptom, as you may have a multi-layered problem; your catalytic converter could be involved, for instance.

Cost for replacing spark plugs

To replace your vehicle’s old spark plugs, the cost might vary greatly depending on how many cylinders it has and what type of spark plugs it requires. Starting at $120 for a 4-cylinder engine with a basic set of spark plugs, the price can go up to $200+ for precious metal spark plugs. For six-cylinder and eight-cylinder engines, spark plug prices are expected to rise. If the inlet manifold needs to be removed and reinstalled, the cost of replacing the spark plugs might range from $200 to $300 or more.

Tips for maintaining spark plugs

  • Find the spark plugs in your car’s cylinders and replace them as needed. Each of the four to eight wires that lead into the main cylinder head is often located directly under the engine case. Getting to them may be difficult, so consult your owner’s manual if you’re having trouble.
  • Before removing each spark plug from the combustion chamber, disconnect the wires and ignition coil for each spark plug. Extending your wrench may be necessary if you want to get into all of the cylinders. Before you remove the leads, make sure they are numbered so you can put them back in the correct sequence when you reinsert them.
  • Always torque the coil’s mounting thru-bolt to the required torque. Vibrational failures can be caused by through-bolts that are too loose. Premature failure of a thru-bolt can be caused by a fractured coil mounting ear and excessively tightened thru-bolts. A diagnostic nightmare can ensue if you don’t get it right the first time.
  • Make that the spark plugs are in good working order. Inspect the spark plug for any signs of corrosion, wear, or deposits. The electrode on the tip of the plug should be clean and free of buildup and not be worn down or rusted.
  • An oil- and water-free spark plug hole or tube is essential. Removing the spark plug can be difficult if there is anything in the tube or well. The secondary ignition generates static electricity that draws small particles to the insulator over time, resulting in a path to the earth. To prevent a misfire in the future, check for oil or other debris in the spark plug tube and well by inspecting the valve cover gasket.

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