car shakes when idle and accelerating

My car shakes occasionally (when idle and accelerating). Every once in a while when I turn my car on it starts shaking and when I start driving, it is as if the car lost half of its acceleration power. Sometimes the idling starts in the middle of the highway at high speeds and other times its right when I start my car.

It accelerates really slow (while slightly shaking). Sometimes I pull the car aside and turn off and start the car 3-4 times and the engine somehow works itself out. I think there is a problem with one of the pistons. A few times the shaking did not stop itself so the car start

Experienced mechanics share their insights in answering this question :
It is very possible that you have a valve cover gasket or spark plug tube seal leak on your vehicle. These type of leaks will allow oil to leak onto the spark plugs causing misfires. When the engine misfires due to oil getting on the spark plug, the engine oil will burn. Since oil and tires are both petroleum products, they will both smell similar when they are burning. I would recommend having an oil leak inspection performed by a qualified professional to determine if there is an oil leak. Consider YourMechanic as an Oil/Fluid leak inspection can be peformed at your home or office.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Motor mounts: It`s the job of the motor and transmission mounts to dampen vibration. When they break, you`ll feel excessive vibration, especially at idle. You can diagnose this yourself by putting your car in neutral. If the shaking lessens, you very well could have broken mounts.
Common reasons for this to happen:

Loose connections at the positive and negative battery terminals. Very dirty or clogged air filters can also cause your engine to underperform. Loose timing belts are another likely cause. A mechanic will check these and replace them if they appear loose and worn.

Motor mounts keep your engine attached to the car. Weak or broken mounts can`t hold the engine tight in the engine compartment and creates a vibration at idle. If the shaking subsides when the car is in Neutral, this could indicate the motor mounts are responsible for the vibrations.
Tires. This is usually the most common cause of unwanted shaking. Unbalanced tires on your Sentra can cause the steering wheel to shake when you accelerate to 50 miles per hour. This shaking generally stops once you exceed 65 miles per hour because of the extremely fast rotations.
The most likely cause of the shuddering most often happens in the vicinity of your car`s rims and tires. They plant your car to the road, and if anything is broken, will feel it. On a serious note, it may be a broken transmission mount or a broken caliper.
The only fix is to completely replace the CV joint. The main purpose of motor mounts is to attach a car`s engine to the frame of the vehicle. A secondary purpose is to dampen or reduce engine vibration so the occupants of the car don`t feel the constant shaking or vibrating of the engine while it`s running.
The most prevalent cause of vibration is problems with your wheels or tires. The potential problems include improper wheel and tire balance, uneven tire wear, separated tire tread, out of round tires, damaged wheels and even loose lug nuts.
Some simple warning signs that the transmission is having problems: Transmission is slow to respond when shifting. Grinding, shaking, vibrating.
If you begin to feel persistent shaking in your car, it`s best that you get to the problem right away before continuing to drive. Continuing to drive with the shaking can result in further damaging parts, ruining your tires, and other costly problems that could be avoided by a quick trip to your mechanic.
You could have a damaged or broken motor mount. Motor mounts are the things that attach the engine to your vehicle`s frame. That sounds serious because it is, and damage to one or more of the motor mounts can allow the engine to vibrate and move around when you press the gas pedal.
Low automatic transmission fluid can cause shaking. If the shaking is accompanied by the check engine light, it`s time to visit a mechanic.
A car`s engine vibrates when idling typically at optimum levels. The transmission gears, rotation of the crankshaft, and other components cause slight vibrations when your car is normally in motion. However, in case there`s too much vibration when the car is idle, there is something wrong with the engine.
The Motor`s Mounts are Damaged

One reason your car could be shaking with acceleration is that the engine`s mounts are broken. If even one of the motor mounts is broken, this could occur, and puts more stress on the remaining mounts. Replacing broken motor mounts is one way to stop vibration during acceleration.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

car shakes when idle and accelerating
ANSWER : It is very possible that you have a valve cover gasket or spark plug tube seal leak on your vehicle. These type of leaks will allow oil to leak onto the spark plugs causing misfires. When the engine misfires due to oil getting on the spark plug, the engine oil will burn. Since oil and tires are both petroleum products, they will both smell similar when they are burning. I would recommend having an oil leak inspection performed by a qualified professional to determine if there is an oil leak. Consider YourMechanic as an Oil/Fluid leak inspection can be peformed at your home or office.

My car has a rough idle when I start my car, when I stop at a light my car turns off. Is it the purge sensor?
ANSWER : This may be a result of a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. Since this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

My car shakes when I accelerate, but stops once I let off the gas.
ANSWER : Hi there. Typically when you accelerate and the engine or steering wheel is vibrating, it’s due to motor or engine mounts being worn out. During acceleration, the motor mounts the engine vibrates naturally as RPM’s increase. Engine mounts are the component responsible for securing the engine of a vehicle to the chassis. They come in a variety of shapes and sizes to fit a wide variety of needs, but they all serve the same purpose of mounting the engine and dampening engine vibration. However, it’s also possible that a vacuum leak exists or something entirely different is causing this vibration. It’s probably best to have one of our professional mechanics come to your location to complete a steering wheel is vibrating inspection. This will allow them to isolate the source of the problem and recommend the correct repairs.

Got my rear main seal fixed, but my car keeps having a rough idle, cutting off & the Electronic Throttle Control Light is on.
ANSWER : It sounds like you may have a faulty electronic throttle control unit. The electronic throttle unit opens and closes the throttle blade based upon input from various engine control sensors, including the accelerator pedal. This unit also controls, among other things, the cruise control function as well. When this control unit fails, this may cause intermittent stalling issues and rough idle problems. This is usually repaired by removing and replacing the throtte control unit. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle at your earliest convenience.

What does my car start shaking when idling 1997 Ford Taurus
ANSWER : Hello. This can be caused by a number of things. Most of the time the issue is caused from a vacuum leak in the engine or a failure in the idle control valve. This is only true if the issue only happens at or near idle. I usually check these first and then check to make sure that the spark plugs are fine. If this occurs at higher speeds also then I will usually also test the fuel pressure to make sure that the fuel pump is not failing. If you want to have this running problem repaired, consider YourMechanic, as a certified mechanic can come to you to [diagnose why the engine is stalling] https://www.yourmechanic.com/services/car-is-stalling-inspection

My car is idling very rough.
ANSWER : The idle air control valve is common for causing a rough idle in many cars, but it sounds like you have already corrected that. Another thing you may also want to check is the crankshaft position sensor. A crankshaft position sensor monitors the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing and other engine parameters. When this is faulty or not working properly, this will cause problems with the ignition system and generating spark transmission to the spark plugs resulting in starting problems, rough idling and other performance issues. You may also want to check the fuel pressure as low fuel pressure can also cause rough or poor idling if the fuel pattern being sprayed from the injectors is not consistent. This can also happen in the case of having dirty fuel injectors which may also interrupt the spray pattern of the injectors. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your car.

High idling, jumping while idling, idle air control valve code
ANSWER : Hi there. This can be caused by the issues that you mentioned or a number of other things. You need to make sure all of the connectors are making good contact. I would then need to know what codes are in the computer to know if this is a circuit issue or not. Most of the time, it is not the circuit but instead a vacuum leak.

If there is a vacuum leak, then the vehicle will act like this and the computer cannot control the idle. Most of the time it is a bad hose or an EGR valve that is stuck open. That is the most common cause for this. I typically remove the EGR to check it to feel the diaphragm on the bottom of it to see if it is moving correctly. If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair your car’s idling issue.

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you