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Why Is My Car Idling Rough?

Mechanic taking a look at the engine of a vehicle with hood up

When you notice your car is idling rough, it is a cause for instant concern. There are many factors that can play into why you're experiencing this problem. You'll want to address the issue and fix the problem sooner rather than later.

Common Reasons Why an Engine is Idling Rough

A good indication that there are problems with your engine is rough idling. This problem is easy to identify as you'll hear strange sounds when you start your vehicle. You may also notice shaking and vibrating. Your vehicle's performance overall will be poor with decreased fuel efficiency and irregular RPMs. There are many causes of rough idling and it's important to get your engine checked when you notice a problem.

Bad Spark Plugs

Spark plugs are responsible for igniting the air and fuel mixture within the combustion chamber. Oil and carbon deposits collect on the spark plugs and wires over time. This can lessen the power when you start your car. Changing the spark plugs may solve the problem of rough idling.

Vacuum Leak

The many hoses surrounding an engine are meant to create a vacuum seal for the air and fuel controlled by the throttle to regulate airflow and engine speed. Over time, exposure to extreme temperatures can cause such hoses to wear out leading to air leaks. Misfires and irregular RPMs will happen when too much air is added to the air and fuel mixture and this will lead to rough idling.

Clogged Fuel Injector

Rough idling can be caused by a dirty fuel injector. The fuel injector dispenses the correct amount of fuel into the engine's cylinder at the exact time. Because of constant exposure to fuel pressure and extreme temperatures, carbon builds up and blocks the nozzles. This prevents the necessary amounts of fuel to pass to properly complete the combustion process. This will result in rough idling.

Carburetor Issues

Older vehicles use a carburetor rather than a fuel injector system. A carburetor that is working properly will keep your car running smoothly and won't produce excessive black exhaust. If you notice a lot of black exhaust, then you could have a problem with the carburetor that causes the engine to idle roughly.

There are many reasons why your car is idling rough. It could be something simple or it may be an expensive fix. It's best to have the problem diagnosed right away. If you need vehicle repair, we invite you to bring your car into our auto repair shop today!

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