For most of us, we jump in our cars and think very little about how they work or operate. They start up when we turn the key. They go when we push on the accelerator. They stop when we hit the brake. What else is there to know?

But where you start to notice your car is when things don’t work the way they should.

If you turn the key and it doesn’t start, you know you have a problem.

What is idling? 

The definition of idling refers to the process of a vehicle’s engine running when it isn’t in motion. If you leave it in park after you turn it on and listen to the engine, that is idling. When you sit at a stoplight waiting for the signal to tell you it’s safe to turn, that is idling.

Idling allows a car’s engine to run without the stress or load of any of the other engine accessories running. It keeps the car ready and waiting for when you demand more.

When it idles normally, you probably don’t notice it. You don’t focus on it.

But occasionally, you’ll notice a change. It seems a little rougher than normal. You might even have trouble keeping your vehicle running.

What does a rough idle mean? 

A rough idle means different things to different people. Some will come in and report their car shakes; the car feels like it’s moving even when sitting still. Others will say it sounds awful, almost quakes and moves. And in other cases, no matter what the owner tries to do, the car just won’t stay running. It turns over, it idles rough, and then stalls altogether, no matter what they do.

Of course, how bad it idles often determines how quickly an owner takes action. A few jitters often fall into the “wait and see” category. There’s not much you can do if your car won’t stay running.

When you start to notice your car isn’t running as it should, pay attention to all the details. Not just what you can feel. Yes, your car might shake and jump. But look around. What else is happening?

• How much fluctuation is there in the RPMs?
• How consistent is the problem?
• Does it only happen when you first start the car on a cold morning?
• Are there other strange noises?
• Do you notice smoke?

Report anything else you notice to help your mechanic make a correct diagnosis.

What causes rough idle and loss of power?

If you have a problem with rough idling, it can range from simple to severe. Fixing the problem right away can ensure no further damage is done to your car. Any of these causes could be at play.

Bad Spark Plugs

A rough idling car can be the result of bad spark plugs or a problem with the spark plug wires.

The spark plug has two primary functions. The first is to ignite the air/fuel mixture within the combustion chamber. The second is to remove the heat from the combustion chamber.

The spark plug must be kept at a low enough temperature to prevent pre-ignition, and high enough to ensure ignition. The spark plug is technically a heat exchanger to transfer energy within the car’s ignition system.

If anything goes wrong with either of those processes, you may notice a rough idle or loss of power.

Leaks

If you’ve ever looked under the hood of your vehicle, you know it’s a myriad of hoses linking all of the different systems together. Over time, hoses wear and may eventually leak. This can limit both air and fuel to flow properly throughout the fuel system, which may cause your engine to idle rough, trying to compensate for the lack of air or fuel.

Dirty Fuel Injector

Think about all your vehicle goes through throughout the year. From hot weather in the summer, to below temperatures in the winter. It deals with ice, salt, and mag chloride spraying up and covering various parts of the undercarriage. And no matter how well you care for your car, things can get dirty pretty quickly.

A car’s fuel injectors control how often and how much fuel is released into each cylinder. They provide the engine with the amount of fuel it needs to run at optimal performance. If the fuel injectors are dirty, they can stunt that process. They can cause a rough idling engine, or stop the operation altogether.

Clogged Air Filter

Over time, the air filter can become clogged with dust, dirt, and other debris. Once clogged, those particles can migrate into other areas of the engine compartment and impact the way your car starts and runs. That’s why car manufacturers recommend you get your air filter checked and replaced routinely along with a motor oil change. It’s a simple, cost-effective process that can give your vehicle a longer life.

Worn Oxygen Sensor

It might also be something as simple as your oxygen sensor. The oxygen sensor is a part of the emissions system, designed to ensure the oxygen to fuel ratio is correct. As this sensor begins to wear out, the ratio can be thrown off, leading to too much air or fuel being supplied to the system. Not only will this cause a rough idle, but it can also impact your fuel economy. If you notice both at the same time, it’s a clear indicator something is wrong with the oxygen sensor.

How do you fix a rough idle?

While there is a long list of potential problems that could be causing your car to have a rough idle, pinpointing the reason can be difficult at best.

One of the best ways to prevent rough idle is by being conscious about your scheduled maintenance.

Stick with a schedule for regular oil changes. Replace all filters regularly, or as a technician tells you it’s time.

You should also take your vehicle in annually for an inspection to ensure all systems are operating as they should. With a simple process, we can diagnose your car for issues with each of the systems: engine, emissions, transmission, braking, and more. Plugging your car into a diagnostic tool will provide error codes, and give the mechanic a better understanding of any issues your vehicle may face.

If you do this early enough, you’ll have more options for how to fix it. And your car won’t leave you stranded at the most inopportune time.

When was the last time you scheduled a service visit? Do it today.