Your Car Shakes at Idle But Smooths Out While Driving – 5 Causes & Fixes

If your car is shaking at idle but smooths out while driving, you might be concerned that something is wrong with the vehicle. However, there are several possible reasons for this type of problem. We’ll help you diagnose the causes and suggest the common methods used to fix this issue.

Car Shaking While Idle – Quick Solutions

car shaking while idling

There are a few things that can cause a vehicle to shake at idle but smooth out while driving. The first thing to check is whether or not you have low oil levels in your engine. If so, then there may be some debris in the oil pan that is obstructing proper lubrication of the engine parts. This can cause vibration and shaking at idle, which will eventually smooth out as the debris is removed from over time.

Another common cause of this issue is faulty transmission seals or gaskets. If these components fail, then they will allow for excessive oil leakage into the engine area which causes vibrations and shaking at idle as well as during acceleration.

When your car is idling, it doesn’t just stay still—it also vibrates in a specific way. The reason behind this phenomenon is gas pressure in your cylinders moving around as they absorb heat from the engine. This movement causes air around them to vibrate too, which can cause more noise than normal while driving or idling at low speeds.

The way around this issue is by adding an air gap between your cylinders and their valves so that there is less chance of vibration picking up speed after being stopped for a while.

It’s important to note that this solution won’t completely eliminate vibration caused by running engines at low speeds or idling for long periods of time; however, it should help reduce it significantly if done properly!

Reasons Your Car Shakes at Idle But Smooths Out While Driving

If your car is shaking during idle, there are a number of potential causes. It could be caused by a bad motor mount, worn belts or hoses, or a defective idle speed control system. Finally, you need to examine the fuel intake system to see if that’s to blame.

1. Motor Mounts

The motor mounts are the supports that hold the engine in place within its compartment. They help to hold the transmission and engine to the subframe, at the same time absorbing shocks and vibrations so that the driver does not feel any of those impacts when the vehicle is running. When these mounts break, it can no longer hold the engine properly in place, resulting in uncontrollable shaking and vibration.

2. Spark Plugs

The spark plugs play a significant role in the combustion process; they provide the spark that helps the engine ignite the fuel. Spark plugs are made of a metal core that is wrapped in a wire shell and coated with an insulator. The insulator prevents heat created by combustion from reaching the wire shell, so it doesn’t melt or burn away. If any of these sparks plugs become worn out or dirty, they will not be able to function properly, thereby causing the engine to exert more stress in the combustion process. When this happens, the engine will misfire and shake randomly.

3. Belts/Hoses

For a smooth ride, the vehicle’s various belts and hoses must be in perfect working order. A faulty belt or hose could result in excessive noise in addition to vibration. Think about the serpentine belt’s worth. It can increase vibration and shaking if it becomes worn out or loose, and if it breaks, a worn belt might harm important parts. A vacuum hose may be to blame if there is a severe shaking that is taking place. Additionally, it may result in engine reluctance or surging, which lowers performance.

4. Speed Control or Throttle Body

Most passenger cars are built with idle speeds between 600 and 1,000 RPMs. The engine shouldn’t stall when operating at this rate. Additionally, it guarantees that the air conditioner and other devices have access to enough power. A valve called an idle air control (IAC) relies on some engines. The engine’s idle rotation speed is controlled by this mechanism. But it can also develop carbon deposits, which will make it behave strangely. An IAC is not present in every car. In fact, a lot of contemporary vehicles have throttle bodies that are controlled electronically, so most individuals won’t have a problem with this option.

5. Fuel Intake System

During idling, if the automobile shakes or vibrates excessively, the gasoline intake system can be at fault. The fuel intake system in your car suffers damage while you’re driving. In extreme cases, the valves get clogged from all of the buildup. The engine cannot receive a steady stream of gasoline if the valves are blocked.

Instead, a discrepant amount of fuel is delivered, which causes vibrations while the engine is idle. If you think the engine is running poorly at idle, check the issue codes with an OBD2 scanner. This will enable you to locate the problem more quickly and affordably. You should unquestionably inspect the spark plugs and ignition coils if there are misfiring issue codes.

reasons a car shakes at idle but smooths out while driving

How to Fix Car Shakes At Idle But Smooths Out While Driving

1. Change the Motor Mounts

There is a good possibility that one or both of the motor mounts are damaged if the engine idles with considerable motion but otherwise runs smoothly. Pushing the engine in various directions can be used to test whether it is loose. It must be changed in order to stop the shaking caused by a damaged motor mount.

2. Clean or Replace Spark Plugs

There is a good probability that the spark plugs are damaged if your automobile misfires when it is idle. You can clean the spark plugs if they are dirty. To clean the electrode of debris, use a wire brush and a spray-on cleaning designed for plugs. Replacing tainted spark plugs, however, can be preferable financially.

3. Change Worn Belts/Hoses

Depending on whatever component is damaged, replacing a worn belt or hose can cost more or less. A serpentine belt replacement, for instance, might cost $100 to $300. The work may cost $75 to $225, although the belt alone may just cost $25 to $75. The cost of replacing a vacuum hose, however, might range from $150 to $1,000. The cost is based on the location of the vacuum leak and how challenging it is to reach it.

4. Modify Idle Speed Control

Both the IAC and the throttle body can be cleaned. It is frequently located on the intake manifold near the throttle body. The IAC can only be replaced if cleaning it doesn’t work. The final price could range from $100 to $500. The parts, however, often account for $50 to $300 of the cost.

5. Fuel Intake System Restoration

To ascertain what services are required, examine the gasoline intake system. During this inspection, it’s a good idea to check the fuel pump as well. Depending on the requirements of the vehicle, fuel induction services differ. Sometimes all that’s needed is a fuel induction cleaning. Sometimes it’s also necessary to service the intake valves, throttle plate, and intake manifold.

fixes for a car shakes at idle but smooths out while driving


Can bad spark plugs cause car to shake?

When a car shakes while idling, the problem could be a faulty or defective spark plug. Uneven fuel combustion during an engine’s combustion process is caused by faulty spark plugs. The RPMs will fluctuate and the engine will make a loud noise when this occurs.

What sensors can cause rough idle?

A rough idle may be caused by an airflow sensor that is broken. The amount of air entering the fuel injection system is measured by a mass airflow sensor, which transmits the data to the car’s computer.

Why does my car vibrate so much when idling?

If your automobile shakes a lot when it is just sitting still, its motor mounts most certainly need to be replaced. The motor mounts of an automobile are in charge of reducing vibrations, particularly when the car is idle.

Can clogged fuel injectors cause vibration?

Vehicle vibration can be brought on by clogged fuel injectors. A clogged fuel injector will naturally make it more difficult for the related cylinder to ignite properly.

Can a bad battery cause my car to shake?

The automobile will ultimately start to wobble, stall, and occasionally halt due to the strain the engine must endure to continue operating on inadequate battery power.


The majority of the causes and fixes for the issues that cause your automobile to shake at idle but smooth out while driving have been discussed in this article. It is essential to address mechanical issues as soon as possible to prevent them from developing into more challenging issues. Therefore, if you are currently experiencing this issue, be sure to follow the above suggestions or get in touch with a professional vehicle repair to identify and resolve the issue.