6 Reasons Why a Car is Shaking When Idle

Does your car vibrate or shake when it is stopped?

The dashboard of your car is how your car talks to you. It tells you how fast you’re going, how much gas you have left, and even reminds you to put your seatbelt on. Few of us pay attention to another gauge on the dashboard, but it’s there for a good reason.

The RPM gauge, which is also called the tachometer, shows how many times the engine turns over every minute.

While the car is sitting still, the engine will turn about 10 times or more per second. Because of how fast it goes, the gauge shows numbers in groups of 1,000. If a vehicle is running normally, it should be about 1,000.

When a car’s RPMs drop below normal or keep going up, especially if the car vibrates when it’s idling, something is wrong.

Why does my car shake when it’s just running?
If an engine runs well and idles smoothly, it means that the fuel and air going into it are mixing in the best way. A good engine can also produce the power needed to run important systems like the cooling system, power steering, air conditioner, and electrical system.

Most of the time, a car vibrates because it is running too rough. If your car has idling problems that make it vibrate or feel slow, this is called “rough idling,” and it’s a sign that your car needs help. It’s telling you that a part has broken down or is about to break down and needs to be fixed soon.

If you wait too long, you might get stuck or have to pay for expensive repairs.

Rough idling often leads to poor performance, bad gas mileage, trouble starting, and high or low RPMs, and it may be a sign of bigger engine problems in the future.

car shaking when idle or stopped

Most cars today have computers built in, and those computers have sensors that watch over different parts of the car to make sure they work properly. For example, the emissions system checks the fuel combustion and exhaust system to make sure the car keeps putting out the right amount of pollution.

If the system fails and works outside of the parameters that were set, or if the car has a rough idle, the computer will make a code that turns on the check engine light. Most of the time, a rough idle is caused by:

The fuel injectors are dirty

Modern cars are high-tech machines that are made to use as little gas as possible. One way to do this is with high-pressure fuel injectors that put the right amount of fuel into each cylinder of the engine at the right time. Fuel injectors are exposed to high temperatures and fuel pressure.

Over time, the carbon left over from the combustion process can clog the tiny nozzles on the fuel injectors, which are called pintles. When fuel injectors are clogged, they can’t release the right amount of fuel for combustion, or the spray pattern doesn’t work well enough to make combustion happen. This leads to poor performance and a rough idle.

Worn Spark Plugs, Spark Plug Wiring, and Ignition Coil


In order for the combustion process to work, air and fuel must be mixed with a spark. Each cylinder’s voltage is made by the spark plugs, their wiring, and the coils. Old or worn-out spark plugs get dirty from oil or carbon deposits, which makes them much less powerful.

If you change your spark plugs every 30,000 to 50,000 miles, you’ll always have enough spark. Plus, you can keep the electrodes from getting damaged, which could cause major problems with the ignition system.

In addition to engine problems, rough idling can be caused by broken ignition parts. Like spark plugs, the ignition coil can start to break down over time. This can lead to misfires, a check engine light, and a car that doesn’t run smoothly.

Clogged Air Filters


Can’t Start Your Car? The fuel filter might be clogged.

As you drive down the road, your engine’s air filter is catching all sorts of things that could be bad for your engine. Over time, these filters get full of dust, dirt, and other particles that stop the right amount of air from getting to the fuel mixture. This makes it harder for the fuel to burn.

When there isn’t enough air, the car runs “rich,” which can make it idle roughly and cause it to use more gas.

Vacuum Leak

With the help of a throttle that controls engine speed and airflow and a vacuum in the intake manifold, the hoses under the hood of your car create a vacuum for air and fuel. Rubber hoses wear out over time, especially in Arizona, and may even start to leak. \

When too much air is added to the fuel mixture, the engine will start to misfire. This will make the engine idle rough and cause the RPMs to go up.

Oxygen Sensor

Part of the emissions system is the oxygen sensor, which measures how much oxygen is in the exhaust. This information is sent to the car’s computer so it can figure out the best mix of air and fuel for the cleanest and most efficient combustion.

Over time, the sensor can break if it is always exposed to heat, carbon deposits, or old age. When the oxygen sensor breaks, the car’s computer gets bad data. This can cause the engine to run too rich or too lean, which can make it hard for the car to idle.

The motor mounts

Motor mounts hold your car’s engine in place. The engine won’t stay in place if the mounts are weak. This makes the engine shake when the car is idle. If the shaking stops when you put the car in neutral, this could mean that the motor mounts are to blame.

Chris Miller

Chris Miller is an auto journalist who specializes in reviewing new cars and providing helpful advice on family vehicles. He has a passion for cars and enjoys sharing his knowledge and expertise with others.

 

Leave a Comment