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Bad Spark Plug Symptoms

Are bad spark plug symptoms keeping you up at night? Worry no more! This blog post is here to provide you with all the information you need to know in order to protect your vehicle from further costly damage.

Knowing what warning signs to look out for when it comes to bad spark plugs and faulty spark plug wires can help you take measures to keep your vehicle running smoothly. The bad news is, if these issues are left unchecked, they could lead to costly repairs that could have been avoided by catching them early on. So, let’s jump in!


When was the last time you changed your Spark Plugs?

Spark plugs might not be at the top of your head when thinking about car maintenance, but they are true unsung heroes and an integral part of your vehicle’s ignition system. Though it may not be necessary to change spark plugs every 48,280km (30,000 miles), as recommended by your vehicle manual, it is important to do so in order to ensure optimal performance. If you are a DIYer or looking to save a little money on car maintenance, you can try your hand at this project.


What are the symptoms of a faulty spark plug?

1. Engine has a rough idle

If you notice that your car engine is running rougher than usual when idle, it could be a sign that your spark plugs require attention. Vibrations can start to become noticeable when the spark plugs are faulty, and this can end up causing long-term damage if left unchecked.

2. Trouble starting

Before you panic and blame a faulty battery or lack of fuel, consider faulty spark plug symptoms. If your engine won’t turn over or if it takes several cranks before the engine starts, check the spark plugs first. A faulty spark plug can cause a delay in start up and leave you stranded if not taken care of.

3. Engine misfiring

If your car’s engine is misfiring, it could be an indication of a defective spark plug. You may experience a jerky ride with the engine cutting out momentarily, and higher emissions could also result from this issue.

4. High fuel consumption

One of the most common bad spark plug symptoms is a significant increase in fuel consumption – if you feel like your vehicle is burning through its fuel tank more quickly than usual, bad spark plugs may be the culprit. Oftentimes bad spark plugs can reduce your MPG by 15 to 30%.

5. Lack of acceleration

If you’ve been feeling like your vehicle isn’t gaining even an ounce of power when you press down on the pedal, it may be time to consider a Spark Plug service. As these essential components age, they can become misfiring or clogged over time which makes the car feel sluggish and unresponsive.

6. Black Exhaust Smoke

If you are noticing heavy black smoke coming out of your exhaust, this too could be a sign of bad spark plugs. This is an indicator that there is incomplete combustion happening inside the engine which can cause loss in power and fuel efficiency.

7. The Checking Engine Light is on

Lastly, slathering of oil and carbon or blistering caused by running too hot can cause your engine system to suffer, leading to decreased performance and costly repairs over time.

If you ever feel unsure as to what is going on under the hood, the check engine light is your best ally in these situations. A reliable indicator that something is wrong, this light is invaluable for identifying bad spark plug symptoms early enough for effective repairs.

Related: Camshaft Position Sensor Symptoms?


What are the symptoms of bad spark plug wires?

Bad-Spark-Plug-Symptoms (1)
Bad-Spark-Plug-Symptoms (1)

As I mentioned, the symptoms of bad spark plug wires can be quite similar to those of a faulty spark plug. So if you think something is off with your ignition system, it’s sensible to put the same list of symptoms that I provided before to good use.


What are the differences between spark plug types?

If you’re looking for a spark plug that will stand up to the test of time, a precious metal like platinum or iridium is definitely your best bet. These sparks plugs offer increased resistance against wear and corrosion from the higher melting temperatures and hard nickel alloy electrodes. Not only that, but their superior ignition creates improved combustion, which not only boosts performance but also decreases emissions and boosts efficiency.

Research by Autolite and Bosch show that iridium plugs can last up to 100,000 miles with no electrode wear, while Denso backs their special heat-resistant properties. While they may be more expensive than other options on the market, they are the first choice in spark plug quality recommended by many mechanics.

FAQS about Bad Spark Plug Symptoms

What happens when a spark plug goes bad?

A misfire is the immediate response from an engine when this happens, as one or more of its cylinders won’t be able to produce the power it is supposed to. This not only requires your engine to work harder in order for it to maintain its power, but it will also take away from your fuel economy by consuming more fuel than it normally would.

Can you still drive your car with bad spark plugs?

The short answer is yes, you can still drive your car with bad spark plugs. However, this isn’t recommended as it could potentially cause further damage to the engine and spark plug wires.

Is it safe to replace spark plugs yourself?

Yes, if you are confident in your DIY skills and have the right tools for the job, it is safe to replace spark plugs yourself. It’s important to remember however that even with professional-level tools, it still requires significant knowledge of how an engine operates. For this reason, it’s best to leave spark plug replacement to a professional.

How much does it cost to replace a bad spark plug?

Shopping for a spark plug replacement can be overwhelming, especially trying to forecast the potential cost. To prepare, it helps to know that the nationwide cost of a spark plug replacement this year is estimated to fall within $92 and $339 with an average price tag of $169.

How often should spark plugs be replaced?

If you’re using ordinary copper or nickel spark plugs, they should be replaced every 30,000 to 50,000 miles. Platinum and iridium plugs tend to last longer – up to 60,000 to 150,000 miles. So if you opt for the slightly pricier option then you won’t have to change them as often.


In conclusion, bad spark plug symptoms are signs that there’s a problem somewhere in your system. It may not be serious, but it’s always best to get it checked out for peace of mind. Preventative maintenance is key and occasionally replacing your spark plugs can go a long way towards keeping your vehicle running reliably.

We at Bradscartunes.com are committed to helping provide resources and helpful tips so our customers can best maintain their vehicles. If you’re having any issues or need spark plug advice, never hesistate to reach out to us—we’d love to help.

1 thought on “Bad Spark Plug Symptoms”

  1. It is important to consider that multiple symptoms could have various causes. However, if the vehicle experiences misfires, rough idling, or running issues, one possible cause could be the spark plugs.


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