Car Repair and Maintenance

Car Shakes at Idle But Smooths Out While Driving [Fixed]

Regardless of the brand and type of vehicle you drive, it’s likely that your car shakes at idle but smooths out while driving and you want this fixed ASAP.

Even while it may appear odd, this circumstance isn’t as unusual as you would believe. It’s not always the end of the world when your car shakes at idle but smooths out while driving because it is something that can be resolved.

An issue with your engine mounts may be the cause of your car shaking when it is idle. Engine mounts are designed to secure your engine and reduce vibration. Your engine may tremble excessively if they are worn out or damaged. Your car may sometimes start making weird sounds as a result of this.

Meanwhile, continue reading to know what it means for your car to vibrate and what to do if your car shakes at idle but smooths out while driving.

car shakes at idle but smooths out while driving

What Does Your Car’s Vibration Mean?

The engine, tires, or suspension of your car are likely to be at fault if it vibrates: If you experience engine vibrations, there may be a problem with the motor mounts or the engine itself.

If the vibrations are coming from the tires, wear or alignment issues may be to blame. Vibrations in the seat or steering wheel may indicate that the suspension isn’t working properly.

Why your car shakes at idle but smooths out while driving – Causes

Below are the reasons your car keeps shaking and suddenly smooths out:

1. Worn or loose car mounts

The reason this should be your top worry is that unlike the majority of other possible issues that might cause idle shaking, this one does not reduce power output.

Consider your car mounts as the straps on your briefcase; they maintain the stability and security of the contents even as you swing the bag around.

Your mounts hold the engine firmly in place by preventing excessive vibration. Typically, as you drive, the mounts hold your engine firmly to the vehicle while the engine moves your automobile ahead via the gearbox connection.

When your mounts are damaged, they do not have the typical function of reducing engine vibration. You wouldn’t notice this when driving since the motion superimposes and the vehicle seems regular.

By leaving your car in neutral while it is idling, you may identify damaged mounts. If the automobile vibrations disappear, a mounting issue exists.

2. Defective spark plugs

Your car can shake while idling due to a faulty spark plug. This is so that the engine’s gasoline can be ignited; if the spark plug is broken, the ignition process won’t be as effective. And according to eEuroparts, under no circumstances should you try to start your engine.

Depending on the make and model of your car as well as the kind of spark plug you need, the cost to replace spark plugs will vary. For replacement spark plugs, you can typically expect to spend between $50 and $100. However, the price may be closer to $400 if your car has a really powerful engine.

3. Damaged idle speed control or throttle body

The engine won’t drag at idle thanks to the idle speed control. When energy-consuming functions are activated, the system is designed to keep the engine running as gently as possible while still functioning properly and without stalling. As a consequence, if this mechanism is flawed, the engine stalls and vibrates noticeably.

4. Misfire

A misfire is another frequent reason for a car to shake while idle and causes a perceptible loss of power both while the car is still and moving.

But how can a car misfire? There are several contributing factors, such as issues with the injectors, ignition coils, spark plugs, and the lack of compression.  It might cost as little as $10 to repair a faulty spark plug, but it can cost up to $2,000 to replace a faulty engine piston.

5. Faulty car alternator

The battery is charged by the alternator, which also powers the electrical system. If it’s broken, the battery won’t be charged correctly, which might make the engine tremble. Repairing a damaged car alternator may be quite expensive.

Depending on the issue, you could have to spend a lot of money on a brand-new alternator. Alternators may be highly costly to repair if they malfunction in your car. An alternator replacement might sometimes cost up to $1,000 or more.

6. Broken timing belt

For the engine valves to open and shut at the proper times, the crankshaft and camshaft must be synchronized by the timing belt.

The idle air control valve may not open and close at the proper times if the timing belt is worn out, which might result in the automobile engine shaking. Timing belt replacement is one of the most often expensive auto repairs.

Timing belt replacement might go from $300 to $500, depending on the make and model of your car. That’s a substantial sum of money, particularly if you’re unprepared.

7. Fuel Intake System’s Issue

Your car will shake while idling if your gasoline intake system is damaged. Vehicles need a gasoline supply to move and operate effectively; as a result, the car will respond if the fuel supply is restricted or hindered by certain causes.

The majority of car fuel systems are unclean rather than terrible. The gasoline delivery valve is clogged by accumulated dirt and debris, which makes the car tremble while it is idle.

8. Clogged air filter

Your car’s air filter ensures that air is circulated properly. As a result, if your air filter is blocked with dirt, it serves no useful function. Reduced airflow into the combustion chamber causes the car to shake excessively in response.

9. Broken coil packs

The spark that ignites the gasoline in the engine is produced by coil packs. The engine may tremble if they are damaged because the spark is not being supplied correctly.

Depending on the make and type of your car, repairing a damaged coil pack might be pricey. The cost of the new item and labor should be between $200 and $400.

How to fix shaky car at idle that smooths out while driving

When you’re driving along and your car begins to shake, it may be rather unsettling. But don’t panic; there are a few things you can do to solve the issue.

They include the following:

Check your tires first. The shaking can be brought on by a lack of oxygen. Additionally, make sure that they are equally inflated. Shaking could also occur if one tire is more inflated than the others.

You should also check your engine mounts. Additionally, if they are loose, shaking may result. If they’re loose, you’ll need to tighten them up.

Lastly, if your car is still shaking at this point, you should take it to a mechanic to have them examine it. They’ll be able to identify the issue and restore your car’s smooth operation.


Is it normal for the engine to shake a little?

When the engine is initially started, it could tremble a little bit, but this should pass quickly. If the engine keeps shuddering, there can be a problem with the motor mounts or another engine part. To be certain, have a qualified technician examine it.

Is it safe to drive when your car is shaking?

Driving while your car is shaking is risky and might result in severe auto damage. It is recommended to err on the side of caution and get your car examined by a professional if you are unclear about what is causing the shaking. Once you identify the reason for the trembling, you may take action to solve the issue and resume driving safely.

Can Cars Shake Due to Low Oil?

Your car can shake as a result of insufficient oil. Your car may not have adequate lubrication if the oil level is low to keep all of the engine components functioning correctly. This can cause a great deal of vibration and cause your automobile to wobble.

Check your oil level and top it up if required if you’re worried that low oil is the source of your car’s trembling. To be sure there aren’t any other problems causing the shaking, you should also get your automobile evaluated by a professional.

Can the wrong gear oil cause vibration?

Unsuitable gear oil may create vibration. Both too much and too little of the incorrect grade of oil might be problematic. Too much viscosity in the oil prevents correct flow and increases friction. It won’t lubricate and protect as well if the oil is too thin. In any case, this might result in improper gear meshing and vibrations.

Can transmission cause a car to shake?

Transmission issues may sometimes make a vehicle shake. The torque converter or the transmission’s gears are often to blame for this. Transmission issues are often quite simple to correct, but if they are ignored, they may develop into more serious issues in the future.

Can a bad fan clutch cause vibration?

Yes, vibration can be caused by a malfunctioning fan clutch. The fan clutch is in charge of coupling the engine to the fan, and if it isn’t functioning correctly, the fan may vibrate. Increased wear on the engine and other parts might result from this, which would eventually result in engine failure.

To prevent any damage, it is crucial to get your engine checked out by a professional as soon as you feel any vibration.

Final Words

The engine mounts are the most likely to be the cause of car shakes at idle but smooths out while driving. The engine’s weight pulls down on the rubber mounts when the vehicle is idle, reducing the shaking. When you begin to drive, the engine moves less, putting less strain on the mounts, which limits their ability to vibrate.


Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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