Why is my car juddering, jerking or stuttering and what should I do?

Why is my car juddering, jerking or stuttering and what should I do?
We want our cars to run smooth as butter – so if it starts to judder, stutter and jerk, it’s very disconcerting.

There are various reasons why a car can jerk, which makes it tricky to diagnose the problem if you’re not an expert.

To help you understand the cause of that worrying movement you’re feeling behind the wheel, we look at some different scenarios and what you should do when faced with them…

Car juddering when accelerating

My car jerks and shudders when I press down on the accelerator but stops when I take my foot off the pedal.

What could the problem be?

An acceleration problem is usually the result of insufficient fuel, air, or spark during the combustion process.

Worn-out spark plugs or the electrical cables attached to them are one of the most common causes of cars stuttering. A deficient spark plug causes the engine to misfire, making your car jerk when you accelerate. 

The engine may also be much noisier than it normally is, sounding more like an aeroplane taking off than a car.

A clogged catalytic converter is another reason why a car jerks while accelerating, as a blockage can disrupt the exhaust system’s airflow. 

When you press down on the accelerator pedal, you may notice a delay in your car’s response, followed by a sudden jerk or lurch forward. There may also be a rotten egg smell.

How to fix it

If the issue is something as straightforward as faulty spark plugs, you may have the know-how to change them yourself. You may also be able to unclog minor blockages with a good catalytic converter cleaner.

But if you don’t understand the mechanics of your car very well or it’s a more serious blockage, it’s best to seek expert help. 

Check out our RAC Approved Garage Network to find a mechanic you can trust. It only includes garages that provide quality work and exceptional customer service, giving you peace of mind if your car needs attention.

Book a repair

Car juddering when pulling away

When I set off in first gear, my car sometimes stutters and shakes until I put it into a higher gear. 

What could the problem be?

The most likely reason that a car jerks when accelerating from stop is a problem with the clutch. 

It could be due to worn-out friction material or a pressure plate defect (or combination of both). It could also be caused by an oil leak contaminating the clutch plate. 

How to fix it

If there is a fault with the clutch, you will need to find out whether it’s a mechanical issue or whether the clutch facing has been contaminated. This is best left to a professional to deal with. 

Replacing a clutch is a specialised repair, so take your car to a reliable garage to get the work carried out.

Book a repair

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Car juddering at low revs

My car is very shaky and jerks when I accelerate at low speed but is fine in the higher gears.

What could the problem be?

As well as some of the causes of car stuttering mentioned earlier, moisture in the distributor cap can also make a vehicle jerk when accelerating. If your car is parked overnight in cold temperatures, condensation can form inside the distributor cap, causing the engine to misfire when accelerating at low speeds. 

Another possibility is a problem with the engine mounts, which hold the engine in place to the chassis. A mounting that is loose, worn or broken will cause your car to vibrate at low revs.

How to fix it

Parking your vehicle in a garage or outside porch will help to prevent moisture from forming. If you have to park your car on the street, a thermal cover can help to reduce the risk of condensation.

If the engine mounts need replacing, we recommend getting an approved mechanic to do this because the engine needs to be securely supported from underneath while it’s being fixed.

Book a repair

Car juddering when idle

car-juddering-shaking-idle

 

My engine judders when idling at traffic lights and junctions, and sometimes feels like it’s going to stall. 

What could the problem be?

Along with faulty spark plugs, a build-up of dirt and grime is the likely cause of cars stuttering when idle.

A clogged filter or fuel injection system can starve your engine of fuel or oxygen, causing your car to judder and shake. 

As a car ages and racks up thousands of miles of wear and tear, its valves can become blocked with sludge. If your engine doesn’t get an even and continuous distribution of clean fuel, it can start to shake or shudder while it idles.

If the judder only happens when idling, it could be a small leak on the vacuum side of the engine, or a worn-out electrical component such as the crankshaft sensor. 

How to fix it

Unless you’re a professional mechanic, don’t attempt to replace components yourself. Your garage can have a look under the bonnet and run diagnostics tests to find the root cause of the problem.  

Book a repair

Book an MOT with the RAC today

As a preventative measure to keep your car running smoothly in future, regularly check your engine for signs of dust and dirt clogging up the system, and make sure you have your car serviced once a year or every 10,000-12,000 miles. 

Occasionally, things do go wrong while you’re out on the roads, so be sure to have the correct breakdown cover in place just in case.

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