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Can Bad Alternator Cause Rough Idle? Fix Rough Idling Now


When you start your vehicle or get stuck in traffic keeping the car on, you can feel the irregular jerks from the car’s engine. That’s not a normal condition, and that might happen because of a bad alternator. Therefore, if you are looking for an answer to can bad alternator cause rough idle, this guide will help you in fixing that problem.

It’s true that a bad alternator causes rough idling. Moreover, your car or truck might face a number of different technical issues if the alternator is not in perfect condition. That’s why this post will include how you can fix rough idling in your car and the symptoms of a bad alternator.

Rough Idling

The term “idling” literally means not to move. In automobiles, idling refers to when your car is turned on, and you are not pressing the gas pedal. Moreover, when you don’t put the car into gear, that’s also considered idling.

woman angry for car rough idling

Generally, idling should provide low revolutions consistently. There should not be any abrupt changes in the RPMs (Revolutions Per Minute.) You can check that via a tachometer that displays the RPMs of your car.

If the needle of the tachometer is steady, the engine is properly idling. All the car’s functions, i.e., electrical components, power steering, and cooling, will work smoothly.

Therefore, proper idling depicts that the alternator and engine are working fine.

However, things might become problematic if the tachometer is showing sudden ups and downs. Even though you are not pressing the accelerator, you can hear the RPMs and unnecessary engine revving.

That’s the situation known as rough idling.

Have a look at the Autogage Tachometer.

What Happens in Rough Idling?

Your car will struggle to maintain an idle rate of engine revolutions. The RPMs will increase and fall. That change in RPM can either get high or low, depending on how worse the condition is. Moreover, the engine’s fuel and air will not mix properly.

You can easily identify whether your car is rough idling. Once you diagnose the problem, you have to take quick action because rough idling gradually affects the engine’s performance. That can cause bigger problems like car stalling and poor ignition.

Reasons for Rough Idling

When your car is shaking without pressing the accelerator, that’s rough idling. There are several reasons that cause your engine to act rough. One of the main reasons is a bad alternator.

Bad Alternator Causes Rough Idling

You already know how important an alternator is for your car. It’s the only part that keeps the car battery charged.

bad car alternator

If the alternator stops providing sufficient electrical charge to the battery, the engine may rough idle, stall, and misfire. Not only that, but other electrical components of the car like headlights, GPS, stereo, and emergency systems will also stop performing.

You might have to take your car to an automobile service station and let the team examine it. They can easily identify the issue and guide you on whether the alternator is repairable or you have to buy a new one.

Moreover, you will see the following symptoms when the alternator begins to misbehave.

Car Won’t Start

When you turn the ignition or push the START button, the car won’t start. It’s because the battery doesn’t have enough energy to power the engine. The battery gets energy from the alternator, and since the alternator is malfunctioning, you will not be able to start your car.

However, you can check whether the battery or alternator is at fault.

Try connecting a charger to the battery and wait till it gets some juice. After that, try starting the car.

If the alternator is faulty, it’s recommended to let the mechanics examine it.

Engine Stalls

The engine might stall in the middle of the road. When the alternator stops providing electrical charge to the battery, the engine will gradually become unresponsive.

Besides, this situation is quite dangerous when you are on the road and the engine stalls. It affects the movement of the car and might force you to stop your car wherever you are.

Electrical Components

There are multiple electronic and electrical components installed in your car. Headlights, indicators, stereo, and interior lights are some of them. In addition to that, GPS, Adaptive Cruise Control (ACC), and entertainment systems are also available if you have a modern electric car.

In the newer models, the alternator must perform at the top of its performance because these cars totally depend on electrical energy.

Now, let’s talk about other reasons that cause rough idling.

Fuel Injectors

The fuel injectors provide the exact amount of fuel to the car’s cylinders. The advancement in the automobile industry paved the way toward a more eco-friendly world. That’s why the manufacturers are controlling the carbon-emission using advanced fuel injectors.

However, this advancement has made these injectors more exposed to grime and dirt.

When the injectors don’t provide enough fuel to the engine, your car experiences rough idling.

You can check out this Super Concentrated Fuel Injector Cleaner.

Air Filter

The air filter also needs frequent replacement because when it becomes full of dust, it can no more clean the air that’s coming to the engine.

When the engine gets dirty air, it will go into rough idling condition.

Therefore, it’s recommended to replace the air filter every 12,000 – 15,000 miles for the best engine performance. Also, you should quickly change the air filter if it gets damaged.

man replace car air filter

Spark Plugs and Wires

When you give ignition, the spark plugs connected to the coils via wires provide voltage to ignite the fuel and air for the engine. Since it’s a combustion process, the carbon residue can easily stick to the spark plugs, making them clogged.

Therefore, it’s mandatory to remove the carbon deposits from the spark plugs. Otherwise, the engine will not get enough electrical charge and hence, rough idling.

Similarly, the coils and the wires can get weary over time. The automobile experts recommend changing the spark plugs every year or two to save the engine from rough idling.

Final Words

Your car’s engine needs proper maintenance if you want to avoid rough idling. Even though there are other reasons as well that cause rough idling, the above-mentioned basic techniques are the most basic.

Therefore, It’s better to get help from automobile experts instead of trying to fix the engine on your own.

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