If your car is shaking or vibrating when idling, it could be due to a variety of reasons. In some cases, the issue may be minor, such as a loose part or an engine misfire.
It is important to look into this issue as soon as possible as it could indicate a more serious problem. Let’s take a look at some of the potential causes and why they are problematic.
Why Does My Car Vibrate When Idling?
Engines that operate well and idle smoothly indicate that the fuel and air provided to the engine are mixing at optimal conditions.
Additionally, a well-functioning engine can produce the power needed to operate vital systems such as the cooling system, power steering, air conditioner, and electrical system.
Rough idling is often what causes a car to vibrate. If your vehicle has idling issues that cause unusual vibrations or a sluggish feeling, otherwise known as rough idling, consider it a cry for help from your car.
It’s telling you that there is a component that has failed or is about to fail and needs to be addressed soon. Waiting too long could leave you stranded or stuck with costly repairs.
Rough idling issues often result in poor performance, poor fuel economy, difficulty starting, high or low RPMs, and may indicate major engine problems down the road.
Reasons Why Your car is shaking when idle
Most vehicles today, equipped with internal computers have sensors that monitor various systems throughout the vehicle to ensure systems operate normally.
The emissions system, for example, monitors the fuel combustion and exhaust system to ensure the vehicle maintains the proper emissions.
If the system fails and operates beyond the predetermined parameters or the vehicle experiences rough idle, the computer will produce a code that triggers the check engine light to come on. The most common causes of a rough idle include:
#1. Dirty Fuel Injectors.
Vehicles today are sophisticated machines that are designed to be as fuel-efficient as possible. One of the ways this is achieved is through high-pressure fuel injectors that dispense the optimal amount of fuel into the engine’s cylinder at the right time.
Fuel injectors are exposed to high temperatures and fuel pressure and over time, their tiny nozzles, known as pintles may become clogged by carbon left behind from the combustion process.
Obstructed fuel injectors are unable to dispense the proper amount of fuel needed for combustion or the spray pattern fails to create successful combustion, resulting in poor performance and rough idling.
#2. Worn Spark Plugs, Spark Plug Wiring, & Ignition Coil.
For the combustion process to succeed, there must be a spark combined with the air and fuel mixture.
Spark plugs, their wiring, and the coils create the voltage to ignite in each cylinder. Spent or old spark plugs become soiled from oil or carbon deposits, greatly reducing the power created by the ignition.
By replacing your spark plugs every 30,000 to 50,000 miles you’re ensuring a sufficient spark every time. Plus, you can prevent damage to electrodes, that may result in significant damages to the ignition system.
In addition to engine troubles, damaged ignition components can cause rough idling. Like spark plugs, over time the ignition coil can begin to break down causing misfires, a check engine light, and rough idling.
#3. Clogged Air Filters.
As you drive down the road, your engine’s air filter is trapping all kinds of contaminants that could be harmful to your engine. Over time these filters become full of dust, dirt, and other particles that prevent the proper air flow that is needed to add to the fuel mixture for combustion.
A shortage of air causes the vehicle to run “rich” and may result in a rough idle as well as an increase in fuel consumption.
#4. Vacuum Leak.
The hoses under the hood of your car help create a vacuum for air and fuel along with the assistance of a throttle that regulates engine speed and airflow and a vacuum in the intake manifold.
Over time, especially in Arizona, these rubber hoses wear out and may even develop leaks. When too much air is introduced into the fuel mixture, the engine will begin to misfire, causing rough idle, and an increase in RPMs.
#5. Oxygen Sensor.
The oxygen sensor is part of the emissions system to measure how much oxygen is in the exhaust. This information is translated to the vehicle’s computer to help calculate the ideal ratio of air and fuel for the most efficient and clean combustion process.
Over time, constant exposure to heat, carbon deposits, or age can cause the sensor to fail. When the oxygen sensor fails, the vehicle’s computer receives inaccurate information and may cause the engine to run too rich or too lean resulting in rough idle conditions.
#6. Motor Mounts.
The engine or motor mount supports the engine while dampening noise and vibration. It keeps the engine and transmission away from the chassis to prevent noise and vibration from affecting the rest of the vehicle.
Many engine mounts are fluid-filled and some mounts are electronically actuated. Over time, the motor mount’s rubber insulation can wear out, or the entire component can get damaged altogether and result in excessive vibration at idle.
If left unaddressed, a damaged motor mount can also cause other problems like overstressed components and wires, friction between drive belts and pulleys, and exhaust leaks.
#7. Faulty Idle Air Control Valve.
The idle air control valve controls engine idle speeds and prevents the vehicle from stalling whenever the engine load changes. If the idle air control valve is stuck closed, or inoperative, or if its passages are clogged with sludge, a low or rough idle might result.
Idle air control is necessary to overcome the friction that builds up in the engine caused by cold lubricating oil.
The engine needs more power under cold temperatures, so the idle air control valve opens an intake air passage to let more air into the engine.
The idle air control system is calibrated to maintain a specified engine idle speed regardless of the operating temperature.
A damaged idle air control valve can result in performance issues and cause the vehicle to exhibit symptoms like excessive vibration at idle.
#8. Fuel System Issues.
Several parts in the fuel system could cause your vehicle to vibrate excessively when idle.
The first possibility is a dirty fuel injector. The fuel injector is frequently exposed to high temperatures and pressure, resulting in carbon buildup in the pintle or nozzle.
The cylinder fed by a stuck or clogged injector engine won’t receive the right amount of fuel. This can cause anything from a high-frequency shutter or shake to a mildly rough idle.
A clogged fuel filter can also create the same problem. Over time, the fuel filter can get contaminated, which can slow down the flow of fuel.
A faulty fuel pump is another probable cause of vibration at idle. This part is responsible for sending the right amount of fuel pressure and volume to the engine so that the vehicle can run properly.
Typically, when a fuel pump fails so that it produces air (cavitation) and the fuel system is returnless, air bubbles will have to pass through the injectors and can cause misfires and rough idle.
A faulty fuel pump can also lead to problems like hard starting, stalling, hesitation, and misfiring if left unaddressed.
My Car Shakes When I Step on the Gas
Just like idling, excessive vibrations and shakiness while stepping on the gas can usually be traced to problems with the engine mounts. Whether they’re worn, damaged, or have come loose over time, you’ll be able to feel all the vibrations your engine makes every time you accelerate.
Some other causes of shaking while accelerating include:
- Misaligned steering system
- Loose/worn parts in your suspension system
- Engine misfiring
- Worn spark plugs
My Car Shakes When I Pick Up Speed
While cautiously obeying speed limits, you may have noticed your car shaking more as you pick up speed.
Maybe it’s when you’re accelerating to merge onto the freeway or while passing someone on the interstate or making that last-minute exit. If that’s the case, it’s essential to slow down and bring your car to a shop for inspection.
Shakiness while driving at faster speeds means that your wheels may be out of balance. It could be alignment-related, but that is rare. Either way, we recommend having it repaired ASAP and definitely before driving at higher speeds again.
My Car Shakes When I Step on the Brakes
Our cars need to be safe and reliable when braking, especially when sudden stops are needed. When your car shakes while braking, you might notice your steering wheel shaking back and forth, your brake pedal pulsating, or simply an intense sound and vibration in the front end of your car.
It could also be a combination of these. Shaking when applying the brakes can feel uneasy, causing you to lose confidence or even cause an accident. It’s important to have your car and your brakes inspected at the first sign of any type of vibrations felt while braking.
Some of the common causes may be:
- Warped brake rotors
- Worn out brake pads
- Damaged braking system