Car Shakes At Idle But Smooths Out While Driving – 10 Causes

Written By: Terrence Hines
Category: Driving

It’s always concerning when car shakes at idle but smooths out while driving. Some of the common issues include disruption in the spark plugs, distributor cap, fuel filter, or air filter.

It’s also possible that the car is out of alignment or has a faulty transmission. However, the good news is, this can often be an easy fix!

Car Shakes At Idle But Smooths Out While Driving – 10 Common Causes

Car trouble can be extremely frustrating, especially when the issue is hard to diagnose. If your car shakes at idle but smooths out while driving, you may have a few potential causes.

Common culprits are damaged engine mounts or transmission mounts, worn out spark plugs or ignition wires, or a clogged fuel filter.

These problems can usually be solved relatively easily and inexpensively by a qualified auto technician.

Your mechanic will also be able to advise if further inspection of other parts is needed to fix the issue.

Don’t ignore it – the sooner you get it looked at, the happier your car (and probably wallet) will be in the long run. Here, we have some of the most common car issues that you must aware of.

1. Low Oil Level Or Dirty Oil:

Car maintenance is so important! It can be the difference between reliability and a breakdown. When it comes to oil, low levels or dirty oil can really affect the performance of your ride.

Car Shakes At Idle But Smooths Out While Driving - 10 Common Causes

Symptoms of this can include a car that shakes at idle but smooths out when you start to drive, or unusual noises from the engine compartment.

For a hassle-free ride and to save yourself from unexpected large bills due to car repairs, ensure you frequently check your engine oil level.

Check the manual of your make and model for correct recommendations on how much to fill up when needed. Doing so will guarantee that your vehicle remains running smoothly!

That way, you’ll know that you’re driving confidently with clean and properly-filled oil in your vehicle!

2. Problems With The Spark Plugs Or Ignition System:

Car issues can be a source of frustration, and problems with the spark plugs or ignition system can lead to a whole host of headaches.

If your car shakes at idle but smooths out while driving, the culprit is often one of these two components.

The spark plugs are commonly worn down over time, resulting in poor fuel efficiency and an engine misfire at lower RPMs.

Ensuring that your car’s ignition system is appropriately adjusted will protect you from the danger of misfires and diminished power.

If any such signs are evident, it is vital to get a professional mechanic to inspect them quickly – this can save you from more problematic issues in the future.

3. Clogged Air Filter:

If your car has been shaking at idle but running smoothly while driving, you may have a clogged air filter.

Clogged Air Filter

This issue is often overlooked when it comes to vehicle maintenance, as it can easily be forgotten about until something goes wrong.

A clogged air filter reduces the amount of clean airflow coming into the engine and can cause poor performance, decreased fuel economy, and increase emissions.

Maintaining a regular check-up on the air filter of your vehicle is essential, especially if it has been displaying any signs of poor performance.

This will make sure that no dirty air gets through and further disrupts its efficiency.

4. Faulty Fuel Injector:

Fuel injectors are an essential part of a car’s engine and so when a fuel injector fails it’s important to act quickly.

A certain marker of a malfunctioning fuel injector is your car shaking at rest, yet operating smoothly when in motion.

Many times, this is caused by weakened fuel pressure due to one or more faulty, clogged, or dirty fuel injectors.

Unless the cause is addressed, there can be other problems such as poor gas mileage and difficulty starting the engine.

If you’re having this issue make sure to get it checked out right away as a faulty fuel injector needs professional attention sooner rather than later.

5. Uneven Tire Pressure:

Uneven tire pressure can be a dangerous problem if it’s not addressed quickly.

If you’re experiencing car shakes at idle but smoothing out while driving, this could be a sign of dangerous imbalances in your tires’ air pressure.

Investing in a tire pressure gauge is an essential first step for prevention before any long journeys – and fortunately, they cost just a few bucks!

Check your manufacturer’s manual to ensure that all four wheels have even tire pressure, as well as any spare tires you might have stored away.

When everything adds up correctly, you’ll sail through the road safely and smoothly – not to mention save money on fuel costs.

6. Worn-Out Engine Mounts:

Underestimating the importance of car engine mounts can be a costly mistake, so it’s best to stay ahead in this regard.

If your car shakes at idle but smooths out while driving, worn-out engine mounts are likely the source of the problem.

Worn-Out Engine Mounts

Signs of worn-out mounts include rattling or clunking noises, excessive vibration, and misalignment under the hood.

Also, if you feel the car vibrating in certain gears more than others, it could be a sign of engine mount trouble.

Don’t wait to find out for sure – if your car is exhibiting any of these telltale signs then it’s time to get them checked out by a qualified auto technician before more serious issues arise.

7. Problems With The Drive Shaft, Such As A Bad U-Joint:

Car problems come in all shapes and sizes, and a drive shaft with a bad U-joint is no exception.

If you’ve been noticing that your car shakes at idle but smooths out while driving, it might be time to take your ride in for a check-up.

If examinations and assessments by your mechanics point to a faulty drive shaft, you should address this matter in haste, as leaving it unchecked can lead to dangerous consequences.

Additionally, inadequate suspension and wheel alignment may also be contributing to the quaking vibration–it’s best to have them checked too.

Replacing the joint is usually very straightforward and requires minimal work, so don’t let a stuck U-joint stop you from getting back on the road – sometimes all it takes is a quick fix!

8. Wheel Alignment Is Off:

Car issues can be a nuisance, especially when the root cause of your woes is hard to pinpoint.

If your car shakes when it is idling but then runs smoothly when you are driving, it could be because the wheels are not aligned correctly.

This is something that you should get checked and fixed as soon as possible.

This is caused by the vibrations of your vehicle’s tires not hitting evenly against the ground when sitting still.

It’s important to identify this issue and help repair it, so you don’t have to deal with a shaking car while slowly losing traction and irregular tire wear.

Keeping your wheel alignment off should be an easy fix – make sure you follow the instructions from your nearby car service shop for the most effective solution.

9. Damaged Suspension System:

Having a damaged suspension system can be extremely frustrating! If your car shakes at idle but smooths out while driving, you may need to replace or repair parts of the system.

Car Shakes At Idle But Smooths Out While Driving

To ensure your car stays in superior condition and to prevent expensive repairs down the road, this is the perfect moment to consult with an automotive professional.

A full suspension system inspection should be done which comprises of shocks and struts, springs as well as bushings – all essential parts for a smooth ride.

Steering and handling are also influenced by a properly functioning suspension system so you won’t have to worry about an uncomfortable ride home.

Once you get that taken care of, you’ll be zipping around town faster than ever!

10. Engine Needs Tune-Up:

Keeping up with car maintenance can be a pain but it’s always worth it in the long run.

When you find that your car shakes at idle but smooths out while driving, it might be time to get your engine tuned-up.

Without regularly scheduled tune-ups, your engine may not be running as efficiently as possible – costing you money and performance both in the short and long term.

Scheduling a tune-up is an important part of ensuring that your car continues to run smoothly, so don’t hesitate to make an appointment.

Keeping those components in good condition can ensure you don’t have any unexpected breakdowns – or disappointments when trying to accelerate!

A tune-up help your car become more fuel efficient and extend the life of other engine components. Investing in a tune-up now can save you countless trips to the repair shop.


When it comes to car problems, one of the most common and dreaded is when a car shakes at idle but smooths out while driving.

Often times this indicates an issue with the engine or either of the motor mounts. Maintenance can be a hassle, as pinpointing the exact problem may take time and effort.

Moreover, repairs are often more expensive than regular maintenance tasks like changing oil and rotating tires.

That being said, If you learn about your car, have it checked regularly by a mechanic, and pay attention to any changes, you can help make sure it runs well for years.

Terrence Hines

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