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Why Does Your Car’s Engine Misfire At Idle? Let’s Find Out!

Hi, I'm Azim Uddin, a student who loves cars. Visit carcaresite.com to learn about car maintenance for beginners and experts. In my studies, I found a cool connection between hosting and car care. Join me on this journey where every road has a story, and hospitality meets the thrill of cars. Explore, learn, and enjoy the ride with me!

Hi, I'm Azim Uddin, a student who loves cars. Visit carcaresite.com to learn about car maintenance for beginners and experts. In my studies, I found a cool connection between hosting and car care. Join me on this journey where every road has a story, and hospitality meets the thrill of cars. Explore, learn, and enjoy the ride with me!

Last Updated on May 10, 2024 by Azim Uddin

According to reports, 22.86% of accidents in the United States happen because of engine failures or misfires. So, we must understand the reasons behind this problem.

So, why does a car engine misfire at idle? There are many reasons why a car engine can misfire at idle, such as:

  • A malfunctioning fuel pump
  • Clogged fuel injector
  • A damaged spark plug

In this article,  we will talk about the common factors that cause car engines to misfire while idling and suggest some solutions to this issue. So, let’s get started!

car engine misfire at idle

Car Engine Misfire At Idle: Common Reasons And Solutions

Below, we have discussed some common reasons why your car’s engine suddenly misfires while idling.

The Fuel Pump In Your Car Isn’t Working Properly

The fuel pump in your car has two main jobs:

  1. It sends an equal quantity of fuel to each cylinder in your car’s engine.
  2. It helps control the speed produced by the engine.

However, researchers have found that most fuel pumps tend to fail within 70,536 kilometers of use. Most often, your car’s fuel pump malfunctions when too much water from the water separator in the fuel line enters it.

The malfunctioning fuel pump can’t pump fuel to your car’s engine properly. As a result, your car’s engine doesn’t receive enough fuel and it misfires.

Solution

You should get your car checked by a professional mechanic. They can confirm if it is indeed the fuel pump that is causing your car’s engine to misfire. Then, buy a high-quality fuel pump for around $150-$200 and have your mechanic install it in your car.

See also  What Causes Car Engine Misfire At Low RPM? Let’s Find Out!

Your Car Has A Corroded Or Clogged Fuel Injector

The fuel injectors are usually located in the intake manifold in your car. In your vehicle, the fuel pump transfers fuel to the fuel distributor. In turn, it distributes fuel to the fuel injector.

When the fuel, under high pressure, reaches the injector tips, it sprays fuel into the cylinders of your car’s engine. Thus, the fuel injectors ensure complete combustion in your car’s engine by delivering fuel at the correct time, angle, and pressure.

But often, the following internal components of the fuel injectors get damaged or corroded:

  • Nozzle body.
  • Control valve assembly.
  • Disc plate.
  • Spring.

When this happens, the fuel injector in your car fails to deliver the correct amount of fuel to the cylinders. So, it creates an imbalance in the air-fuel mixture inside your car’s engine. Therefore, your car’s engine misfires at idle.

Clogged Fuel Injector

Solution

If your car has a corroded fuel injector, you might need to take your car to a mechanic and get it replaced. But, if the fuel injectors in your car have become clogged, you should clean them properly with a fuel injector cleaner.

Check out the steps below to learn how to clean a fuel injector.

  • Step 1: Take the plastic straw that comes with the fuel injector cleaner.
  • Step 2: Attach the plastic straw to a small piece of rubber hose using super glue. You should make sure that the diameter of the hose matches the inner diameter of the fuel line.
  • Step 3: Open the hood of your car.
  • Step 4: Use a screwdriver to detach the fuel line from its position.
  • Step 5: Connect the adapter you just made in place of the fuel line.
  • Step 6: Afterward, remove your passenger seat and pull out the fuel pump fuse to disconnect the fuel pump.
  • Step 7: Insert the other end of the plastic pipe into the nozzle attached to the fuel injector cleaner bottle.
  • Step 8: Start your car’s engine.
  • Step 9: Press on the nozzle to spray the cleaner into the fuel injectors.
  • Step 10: Afterward, turn off your car’s engine.
  • Step 11: Carefully remove the plastic pipe from the fuel injector cleaner bottle.
  • Step 12: Now, if you remove the fuel injectors from your car, you will notice that they are cleaner than before.
  • Step 13: Lastly, remove your handmade adapter, reattach the fuel line, and reinstall the fuel pump fuse.
See also  Engine Misfire at High RPM? Diagnosis and Solution

For a visual representation of this process, you can watch this YouTube video.

The Spark Plugs In Your Car Is Damaged

The spark plug in your car has two electrodes inside it. These electrodes are separated by an air gap. Through this gap, an electrical charge is released to create sparks. These sparks kindle the mixture of fuel and oxygen in your car’s engine.

This, in turn, produces power to operate your car’s engine. However, the spark plugs in your car can get damaged for the following reasons:

  • They endure around 150 bars of oscillating pressure regularly.
  • They operate under high temperatures and face thermal shocks.
  • Chemical deposits form on the spark plugs due to chemical reactions.

Therefore, a damaged spark plug can’t produce a strong spark to kindle the mixture of fuel and air in the combustion chamber effectively. As a result, your car’s engine misfires at idle.

Car spark plug issue
new spark plug

Solution

In this case, you should take your car to a mechanic. They can examine your car and identify which spark plug is causing your car’s engine to misfire. Afterward, you should replace the damaged spark plug with a spark plug that has multiple claws, unlike regular spark plugs.

As per researchers, spark plugs with multiple claws can effectively transfer heat and provide stability when there is moderate ignition energy.

If your vehicle experiences engine misfire at idle, you might find our articles on ‘Can a Bad Alternator Cause a Misfire?’ and ‘Car Engine Misfire at Low RPM’ beneficial, encompassing all the necessary information. Can a Bad Alternator Cause a Misfire? provides a comprehensive examination of the common factors contributing to engine misfires. Meanwhile, our piece on Car Engine Misfire at Low RPM delves into everything you need to know!

See also  Can a Bad Alternator Cause a Misfire?

FAQs

For more information on why car engines misfire at idle, you can read the frequently asked questions we have provided below.

Q: How will I understand that my car engine is misfiring at idle?

If your car engine misfires at idle, your car will lose power, the engine will make knocking sounds and it will vibrate. Additionally, you will notice black smoke coming out of your car’s exhaust pipes.

Q: Can an engine misfire at idle affect fuel efficiency in my car?

If your car engine keeps misfiring continuously, it will reduce your car’s fuel efficiency. This happens because the faulty fuel system can’t completely burn all the fuel in your vehicle. As a result, fuel consumption in your car decreases.

Final Words

Overall, when the air-fuel mixture in your car gets imbalanced and complete combustion doesn’t take place, your car’s engine can’t generate enough power to operate properly. As a result, your car’s engine misfires.

Engine misfires mostly happen due to a damaged spark plug, clogged fuel injectors, or a faulty fuel pump. When these parts get damaged, the cylinders in your car start to vibrate and produce knocking sounds. If you notice these issues in your car, it indicates that the engine is about to misfire.

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