Can engine problems cause car to shake?

Car Shakes When Stopped or Idling? Causes & How To Fix It

If your car vibrates when stopped or at idle, a few things could cause it. Here are the most common reasons why it happens.

By Magnus Sellén
Updated: March 6, 2023

When you start up your car, you expect everything to run smoothly. But what do you do when you start your vehicle, and it starts vibrating and shaking?

There are few problems more irritating than rough idle. But with a little know-how and expertise, you can diagnose the cause of your rough idle and have everything running smoothly again in no time.

In this article, we look at some of the most common reasons for a rough idle – and what you can do to fix them.

Table Of Contents show

7 Causes of Car Vibrates or Shakes When Idling

The most common reason your car is shaking when stopped or at idle is due to worn spark plugs or vacuum leaks. It can also be caused by loose or damaged engine mounts, a worn serpentine belt, a bad fuel pump, or any other fuel-related issues.

The first thing you need to do when your car vibrates or shakes at idle is to check the trouble codes with an OBD-II scanner. If you can’t find any trouble codes or just can’t figure out what they mean, we have some possible causes here down below:

Here is a more detailed list of the seven most common reasons why a car vibrates when stopped or at idle.

1. Worn Spark Plugs

One of the most common reasons for a rough idle is worn or damaged spark plugs. If you have worn spark plugs, your engine might misfire, which causes shaking or vibrations. If you have a faulty spark plug, you should have a check engine light on your dashboard, but that doesn’t always happen.

The good news is that spark plugs are cheap, but you should replace them all if one goes bad. From there, you should change your spark plugs every 80,000 to 100,000 miles to prevent this problem from cropping up again!

2. Loose or Disconnected Vacuum Hoses

Whether you know it or not, your vehicle is likely using vacuum hoses to power the air and fuel systems. If these hoses are torn or disconnected, the systems won’t work the way they should, and engine performance can suffer as a result.

It’s not uncommon that when a vacuum problem gets bad enough, the engine misfires as a result. This misfire is what you’re noticing through vibrating or shaking.

3. Broken or Loose Engine Mounts

Your motor mounts hold your engine in place, so it makes sense that the motor mounts might be the problem if you have a shaking or vibrating engine. Inspecting your vehicle’s motor mounts can be difficult, depending on what you drive.

One easy way to check the motor mounts is to open the engine bay and have someone rev the engine while you’re looking at it. If the engine “jumps,” then you have faulty motor mounts.

Motor mounts themselves are relatively cheap, but it can be an extensive labor process to replace them.

4. Worn Out Belts

There might be multiple belts on your engine, but the two that every engine has are the serpentine belt and the timing belt. If either of these belts is worn or damaged, a rough idle is a typical result.

Serpentine belts are easier to diagnose and easier to replace. Simply open the hood and identify the largest rubber belt around the front of your engine. Give it a slight tug; if it feels loose at all, that’s a problem.

From there, check for cracks or tears along the belt. If you see signs of damage, replace the belt.

For timing belts, you’ll need a more comprehensive repair, but often you’ll have a check engine light letting you know about the problem.

5. Damaged or Clogged Fuel Intake/Fuel Pump/Fuel Injectors/Filter

If anything is going on with your fuel system, you’ll likely have a vibrating or shaking engine. That’s because if one of the engine’s cylinders isn’t getting enough fuel, it will throw the entire balance of the engine off.

But even if you’ve identified it as a problem with your fuel system, there are a couple of different potential culprits. The first place to check should be your fuel filter. If your fuel filter is clogged, nothing will work the way it should, and it can even end up damaging other components.

From there, you should look into your fuel injectors, fuel intake, or fuel pump. Many of these issues will cause a check engine light, which can help you narrow down the problem.

6. Clogged Air Filter

Just like fuel is essential to your engine’s proper operation, air is a critical component. Fortunately for you, if the intake system is the problem causing your rough idle, the problem usually originates from the air filter.

Simply pull the old air filter out and check if it’s extremely dirty. If it is, this might be your problem. Replace the air filter, reset the code, and see if the problem goes away! Air filters typically cost between $15 and $40, and most part stores will replace them for you for free.

7. Faulty Camshaft Timing

Engine vibrations and shaking typically mean that your engine is misfiring for one reason or another. A potential reason for an engine misfire is faulty timing. If you just completed significant work on your engine, this is more common, but it’s not unheard of to have timing issues if the belt or chain is worn or damaged.

If you need to replace your timing belt, it’s relatively expensive due to the labor involved.

The Basic Mechanical Breakdown

There are two main reasons that your engine might vibrate or shake while you’re idling, but the causes for these issues vary.

The first issue is an engine misfire. This occurs when your engine’s spark plug fires at the wrong time or there isn’t enough fuel or air in the combustion chamber to match the rest of the engine’s performance. If you leave this problem alone, you risk damaging your engine block, requiring you to replace your engine.

The second issue is a mounting issue. Your engine creates a lot of force, which is why the manufacturer mounts it to your vehicle’s frame, so it doesn’t move around. But if these mounts aren’t doing their job, your engine will shift around.

By the time you’re feeling it when you idle, the problem is severe enough that you shouldn’t drive the vehicle anywhere before it’s repaired.

Conclusion

While it can be tempting to ignore a rough idle for a while because your vehicle is still running, this is the last thing you want to do. The longer you let the problem go, the more likely it is to develop into something more serious.

Before you give your engine a chance to break, fix the problem! If not, a problem that you could’ve fixed for a few hundred bucks might cost you a few thousand.

8 Reasons Your Car Vibrates When Stopped or Idling (and How to Fix)

Diagnosing a car that shakes when stopped or idling but not while driving is much easier than trying to figure out why it’s vibrating while accelerating. This is simply due to the fact that the only part moving while you’re stopped is the engine.

The good news is that you can be confident the rough idle issue is engine-related and you can focus all your troubleshooting in that area. The bad news is that an engine is as complicated as it gets when we’re talking about parts of a car.

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Table of Contents

Common Causes of Your Car Shaking When Stopped

#1 – Dirty or Clogged Fuel Injectors

Over time, parts of your fuel system, namely fuel injectors, begin to get clogged up by carbon deposits, varnish, or other sediments. This causes uneven amounts of fuel being delivered with each engine cycle. When this happens, you car will shake, shutter, or vibrate while idling since the constant flow of fuel to the combustion chamber is being interrupted.

Clogged fuel injectors must be cleaned or in really bad cases, replaced. Often, using a good fuel system or fuel injector cleaner will clear things up. Cleaning the throttle body, which controls the amount of air mixing in with the fuel, is also recommended and throttle body cleaners exist for that very purpose.

#2 – Worn or Dirty Spark Plugs

Bad spark plugs are another common cause of your car vibrating when stopped. Dirt and carbon deposit build up will not allow your spark plugs to fire properly to ignite the fuel. This leads to the engine mis-firing which will feel like the vehicle is shaking at idle.

Unless you’ve done so recently, replacing your spark plugs can often make things right. There are many types of spark plugs so you want to make sure you’re getting the correct ones. You should always refer to your owner’s manual for the exact specs. The best spark plugs for your car may be totally different than the plugs your neighbor raves about.

#3 – Disconnected Vacuum Hose

Often overlooked but happens more than you may think, a vacuum hose in your engine may pop off while driving or be accidentally disconnected when working on your car. When a hose comes loose, it can cause the engine to shake and vibrate and possibly even stall out.

A crack or tear in a hose may cause the same shaking, although to a lesser extent. Check all hose connections to make sure they are securely attached. If a hose feels loose, you will need to replace it or it will just come off again.

Small air leaks are the hardest to find. In those cases, you can spray some soapy water along a hose while the engine is running. If there’s a crack somewhere, the soapy water will temporarily seal the leak and you’ll notice a change in idle speed.

#4 – Torn or Cracked Timing Belt

A timing belt (or other serpentine belt) which is stretched, cracked, or partially torn can also cause your car to shake when idling. In case of a timing belt, it’s a warning sign of a soon-to-be timing belt failure which you should appreciate. If your timing belt completely breaks, it can result in major damage to your engine.

It’s critical to follow manufacturer’s guidelines when it comes to timing belt replacement intervals. While it’s not cheap to replace a timing belt since you’ll also be replacing the water pump in most cases, but failure to do so may cause thousands of dollars in damage.

#5 – Dirty Air Filter

Along with an interrupted fuel supply (see dirty/clogged injector above), if your engine’s air intake is interrupted, it can also lead to your engine vibrating and not running as smooth as it should be. When your air filter is dirty or clogged, not enough air reaches the combustion chamber meaning not enough fuel is injected.

This combination will cause your RPM to drop below the normal idle range (usually about 700 RPM), and your car will experience some shaking when you are stopped. In some cases, the RPM will drop low enough where the car stalls and needs to be restarted.

Fortunately, replacing an air filter is a simple do-it-yourself job and a new filter should only cost about $10-$20. Alternatively, you can purchase a re-usable air filter (such as K&N) which you can clean instead of replacing. It will cost you more up front but less money in the long run.

#6 – Clogged Fuel Filter

If your fuel filter is clogged, not enough fuel will be getting from the fuel pump to the injectors. This will cause the same type of shaking as clogged fuel injectors since not enough fuel is getting into the engine.

With a bad or clogged fuel filter, you’ll need to replace it. Since the fuel filter is often located inside the fuel tank or near it, it’s best to leave the job to a professional for most people. But if you have some experience, replacing a fuel filter isn’t too difficult for most vehicles.

#7 – Bad Motor Mounts

Since one of the jobs of a motor mount is to dampen engine vibration so individuals in the car won’t feel it, a broken motor mount will make itself known very quickly. While a faulty engine mount will be more noticeable when the engine is working hard (like when accelerating), shaking and rattling at idle is usually noticeable as well.

If you suspect a bad motor mount, you’ll want to take your car to a mechanic as soon as possible to confirm the issue and have the mount replaced. If left unchecked, it may cause other engine mounts to fail and even cause damage to other parts of the engine.

For instance, the blades in the radiator fan can break from hitting the surrounding shroud because the engine is sitting lower than it should be due to a broken motor mount.

#8 – Faulty Mass Air Flow Sensor

Probably the least common reason for your car shaking while stopped, a bad mass air flow sensor (MAF) can be the culprit. Since its purpose is to properly calculate the air-fuel ratio for the engine, if it goes bad and sends incorrect readings to the car’s computer, the wrong amount of fuel can get injected into the engine at the wrong times.

As already explained above, when not enough fuel gets into the engine than what’s needed, excess vibrating or shaking can be felt. A bad MAF will almost always cause the check engine light to go on so a scan of any stored diagnostic trouble codes can confirm the issue.

Owner at Car Treatments

Having turned wrenches on vehicles for over 18 years, Mark has a passion for cars and writing about them. As the owner of Car Treatments, he works with a team of automotive experts (in their respective fields) to publish new content on a regular basis.

My Car Is Shaking When Idle? 7 Reasons Why

If your car is shaking when idle, there could be several reasons why that is happening. Click on each reason to learn more:

Your spark plugs are worn
Your ignition coil is worn
You have dirty fuel injectors
You have a clogged air filter
You have a vacuum leak
Your oxygen sensor has failed
Your motor mounts are weak or broken

If your car is shaking when idle and you live in the Kitchener-Waterloo region, contact us.

Car is shaking when idle

1. Your spark plugs are worn

Spark plugs provide the spark of electricity needed to ignite the combustion used to start your vehicle. They give off a bolt of electricity that ignites the mixture of fuel and air.

This ignition in turn puts the pistons in your motor into motion which makes your engine run. If you want to learn more about how spark plugs work, watch this video

If your car is shaking when idle it might be your spark plugs

If your spark plugs are older, they may have oil or carbon deposits built up on them which can greatly reduce their ability to function and cause your car to shake.

Solution:

If your car is shaking when idle, you may need to replace your spark plugs. It is a good practice to replace your spark plugs about every 30,000 to 50,000 miles to make sure that they always give you a proper spark every time.

2. Your ignition coil is worn

Your ignition coil is an induction coil that is a part of your vehicle’s ignition system. It is made up of an inner and outer coil.

It works in conjunction with your spark plugs to ignite the fuel and air mixture in your vehicle to make your engine run.

Watch this video to see how an ignition coil works.

If your ignition coil gets damaged, your car will idle rough

The ignition coil takes the low voltage found in your car battery and transforms it into a high voltage. The spark plug then takes the spark created by the coil to ignite your fuel/air mixture.

If your ignition coil gets damaged then your vehicle will experience rough idling.

Solution:

If your ignition coil is damaged, it will need to be repaired, refurbished or replaced. Ask a mechanic you trust to find out which option would be the best for you.

3. You have dirty fuel injectors

Modern vehicles are equipped with high-pressure fuel injectors that are designed to dispense the perfect amount of fuel into your engine’s cylinder at the right moment for optimal performance.

Over time, the tiny nozzles in your fuel injector can get clogged up by carbon that is produced in the combustion process.

The following video will show you how you can tell if your fuel injector is clogged

If your fuel injector nozzles are block, get them looked at by a professional

If your fuel injector nozzles (also called pintles) get blocked, then they won’t be able to give off the right amount of fuel for successful combustion. This can cause your car to shake when it is idle.

Solution:

Even though there are fuel injector cleaners on the market, the most effective way to clean a clogged fuel injector is to remove it from your engine and have it professionally cleaned or replaced altogether.

4. You have a clogged air filter

The job of your engine’s air filter is to trap all sorts of contaminants and debris that could harm your engine. Over time, this filter will get filled up with dust, particles, and dirt.

When this happens, the filter can no longer do its job properly. Your air filter should be replaced about every 30,000 miles. The following video shows how this is done.

Watch how an air filter is changed

If your air filter is clogged, then the airflow that is needed to add air to the fuel mixture for proper combustion can get blocked as not enough air can get through. This could be another reason why your car is shaking when idle.

Solution:

If your air filter is clogged, it will need to be replaced.

5. You have a vacuum leak

There are several hoses in your vehicle that help to create a vacuum that lets air move to your engine.

If your car is shaking when idle it might be a loose or damaged hose

If one of these hoses becomes loose, disconnected, or damaged, then too much air can be introduced into the air/fuel mixture. This can cause your vehicle to misfire or shake when it is idling.

Solution:

You will need to take your vehicle to a mechanic you trust to replace or re-attach your damaged hoses.

6. Your oxygen sensor has failed

Your oxygen sensor measures how much oxygen is in your exhaust. This information is sent to your vehicle’s computer.

The computer takes the information and then calculates the optimal ratio of fuel to air to give you the best combustion process. This video further explains how an oxygen sensor works.

The oxygen sensor send information to your vehicle’s computer

Over time your oxygen sensor can fail. This can be caused by carbon deposits, old age, and constant exposure to high temperatures.

If your oxygen sensor is not working properly then your computer will receive inaccurate information which will throw off its calculations. This can result in your car shaking when it is idling.

Solution:

Oxygen sensors usually can’t be repaired, it will need to be replaced. Sometimes people will try to clean their sensor in order to get a bit more time out of it, but this is just a temporary fix.

7. Your motor mounts are weak or broken

Your motor mounts are the part of your vehicle that attaches your engine to the subframe of your car. The following video will teach you more about engine mounts and how they are attached to your vehicle’s subframe.

If your car is shaking when idle, the motor mounts may be broken

If your motor mounts become weakened or get broken, they won’t be able to hold your engine firmly in place. This can cause your vehicle to shake when it is idle.

If you put your vehicle into neutral and the shaking stops, then that is a pretty good indication that your motor mounts are at fault.

Solution:

If your engine mounts are damaged or broken, they will need to be replaced. You can install engine mounts yourself, however, it is better to have them replaced by a professional mechanic you trust to make sure that they are installed properly.

CAR FEELS SHAKY WHEN Idle? CONTACT HANSMA

If your car is shaking when idle, you can trust Hansma to fix it right and not do any unnecessary repairs. Here’s why you can rely on Hansma for the best auto repair service in the KW region:

Over 33 Years of Service: We have been serving the Kitchener region with the highest quality automotive services since 1987.

Locally Owned and Operated: You can feel good about supporting a locally owned and operated family business.
True Customer Care: At Hansma, we truly care about our customers. We will do our best to provide you with great customer care and service. When you come to Hansma, you will be treated like family.
Honest Customer Service: Our customers have come to appreciate our honest service. Our word-of-mouth referrals continue to be our largest source of new customers.
Competitive Pricing: Whether you are looking for a quick tire change or you require one of our other automotive services, our highly trained technicians will be able to diagnose and fix your vehicle at a highly competitive price.
Reliable Repairs: You can rely on the technical expertise of our friendly staff to keep your vehicle in peak condition.