Car jerking when accelerating or stuttering? How to find the cause

A car jerking when accelerating has three possible sources: the engine, the clutch or gearbox, and the driveline. The moment it happens usually tells you which. Jerking only when pulling away or exactly as it changes gear points to the clutch or gearbox. If it follows engine speed and also happens in neutral, it is almost certainly the engine.

We are a transmission specialist, so we will say this upfront: when someone tells us their car stutters when accelerating or hesitates when pulling away, the cause is often the engine, not the gearbox. This guide shows you how to tell the difference yourself, so you do not end up at the wrong specialist, and what to do if it does turn out to be the clutch or gearbox.

Three sources: engine, clutch or gearbox, and driveline

Jerking, juddering and stuttering often feel the same from the driver’s seat, but mechanically they are different things.

• Engine: combustion is irregular. A cylinder briefly drops out or delivers too little. That feels like a short jerk or a shake, usually linked to engine speed and how far you press the accelerator.
• Clutch or gearbox: torque is not passed on smoothly. That feels like jerking, juddering or a kick as a gear engages.
• Driveline: driveshafts, CV joints, engine and gearbox mounts, or wheel imbalance. That feels more like vibration than stuttering, and often depends on road speed or steering angle.

So you do not need to guess which part is broken. First work out which of these three groups to look in.

When does it happen? From situation to likely cause

Find the situation closest to your complaint. It is the quickest way to narrow down the cause.

For a manual car, read more about clutch plate wear and judder and the dual mass flywheel. For an automatic that kicks between gears, see our article on an automatic gearbox that shifts badly or jerks.

Car stuttering when accelerating: engine-side causes

We do not repair these parts ourselves. We list them because it is a waste of your time and money to bring an engine fault to a transmission specialist. The common engine-side causes of a car jerking or stuttering when accelerating:

• Spark plugs and ignition coils. Worn plugs or a weak coil cause misfires, especially under load. The engine warning light often flashes.
• Fuel injectors. Dirty or leaking injectors cause irregular combustion, on diesels often with an uneven idle.
• Mass airflow sensor and air leaks. A wrongly measured air flow makes the mixture too lean or too rich. Typical sign: hesitation when you suddenly press the accelerator.
• EGR valve and diesel particulate filter (DPF). A sticking EGR valve or a filling DPF causes loss of power and jerky behaviour, sometimes with limp mode.
• Fuel filter and fuel pump. A lack of fuel supply shows up under high load, so on the motorway sooner than in town.
• Blocked catalytic converter. The engine cannot get rid of its exhaust gases, which feels like a car that will not pull and keeps holding back.

Rule of thumb: if the complaint also happens when you rev the engine in neutral or while standing still, look on the engine side. If the engine warning light is on, our article on the engine warning light explains what it means and what to do next.

Clutch and gearbox causes: where our expertise lies

If the jerking is tied to pulling away, changing gear or low-speed crawling, the clutch or gearbox is the logical suspect. These are the causes we see most.

Slipping or juddering clutch

In a manual car, juddering when pulling away is often clutch judder. The clutch plate does not grip evenly, for example because of wear, oil contamination or a distorted pressure plate. If the clutch slips, the revs rise without the car keeping up. Our article on a slipping clutch explains how to check that yourself.

Dual mass flywheel

A worn dual mass flywheel causes rattling at idle, vibration at low revs and juddering when pulling away. It is usually replaced together with the clutch, because the gearbox has to come out anyway.

DSG and dual clutch gearboxes

Dual clutch gearboxes typically judder at low speed, in traffic and when pulling away from a standstill. That is where the clutch has to slip in a controlled way the most. They have two clutches, one for the odd and one for the even gears. With a dry dual clutch, such as the seven-speed DQ200 DSG, it is usually wear and heat in the clutch plates. With a wet version, such as the six-speed DQ250, it is more often the clutch packs, the oil pressure or the control. Outdated adaptation values play a part in both.

For the full picture see our articles on the juddering seven-speed DSG clutch, the Volkswagen Golf jerking when pulling away and the Volkswagen Polo jerking when pulling away. How such a gearbox works is explained in dual clutch transmission (DCT).

Torque converter and lock-up clutch

A torque converter is not a plate clutch. It transmits torque through fluid and is allowed to slip while doing so; that is part of how it works. Only the lock-up clutch inside it is a real friction clutch, which locks the converter mechanically when conditions allow. If that lock-up does not engage smoothly, you feel a light shudder or a repeated surge at a steady speed with little throttle. This complaint is often mistaken for an engine problem.

It can be the fluid rather than the hardware. Honda, for example, issued a service bulletin for a lock-up clutch judder between 20 and 60 mph that turned out to be caused by deteriorated transmission fluid, not by a faulty converter. More in our article on the torque converter.

CVT: push belt or power split

In a CVT with a push belt, slip shows up as the revs rising when you pull away while the speed lags behind, sometimes with judder from the pull-away clutch. Note the difference with a Toyota hybrid: its e-CVT has no belt at all. It is a planetary power split device with two motor-generators. Jerking in such a drivetrain therefore rarely comes from the “gearbox” itself. The differences between the types are in our article on the CVT gearbox.

Mechatronic, valve body and transmission fluid

In an automatic, shift pressure is controlled by solenoid valves and valve spools. Old or contaminated transmission fluid, a blocked filter or a fault in the control unit cause harsh gear changes and sometimes limp mode. Read more about that control unit on our mechatronic page. Which complaints point to more serious damage is covered in gearbox failure symptoms, and the known patterns per make are in our overview of automatic gearbox problems by make.

Driveline: vibration rather than stuttering

If you feel it mainly at a certain speed, or when cornering and steering, it is usually neither the engine nor the gearbox. Think of a worn CV joint, a bent driveshaft, a worn centre bearing, sagging engine or gearbox mounts, or wheel imbalance. A CV (constant velocity) joint keeps two shafts turning at the same speed even when they are at an angle to each other, and when it can no longer do that you feel clicking or vibration, typically on full lock. Read more in our article on the CV joint.

One useful check: driveline vibrations do not change when you coast in neutral, because the wheels keep turning the driveline. Juddering only under braking points to warped brake discs rather than the drivetrain.

When to stop driving straight away

Carrying on can make some faults quickly more expensive or unsafe. Stop and have the car checked if you see or notice:

• a red warning light, especially the oil pressure light or an engine temperature warning;
• a flashing engine warning light, which signals a severe misfire that can damage the catalytic converter;
• limp mode, where the car stays in one gear or no longer pulls;
• a burning smell or the sharp smell of a burnt clutch;
• metallic noises, ticking or grinding that rises and falls with road speed;
• drive that suddenly drops out, or a car that will not accelerate.

How ATR finds the cause of a jerking car

We start with a read-out, and a generic OBD scanner is not enough for that. Generic OBD mainly reads the standardised, emissions-related engine codes, while transmission control units keep their own manufacturer-specific fault memory. So we also read the gearbox module itself and look at the manufacturer’s codes. What those codes mean is explained in our overview of transmission fault codes.

Then comes a test drive in which we try to reproduce the complaint in exactly the situation you describe. During that drive we watch live data: input and output speed of the gearbox, clutch pressure, torque converter slip, fluid temperature and shift times. Finally we look at the adaptation values. They show how far the control unit has already had to compensate for wear, and that is often the clearest evidence of whether a complaint is mechanical or can still be solved with an adjustment.

And if the read-out and test drive point to the engine, we tell you so, and you know which specialist to go to.

What a repair costs depends entirely on the outcome: the type of gearbox, the nature of the damage and whether we can overhaul part of it or the complete unit has to come out. We only give a price indication once we know what is going on. How such a repair works is explained in our article on gearbox repair.

Book your car in with your registration number and a short description of when the jerking happens.

Do you run a garage and have a car with a shift or judder complaint you cannot pin down? With ATR Remote we help garages with diagnosis at a distance.

Frequently asked questions

Can a bad transmission cause jerking?

Yes. A worn clutch, a juddering dual clutch, a torque converter lock-up that engages unevenly, or old transmission fluid can all make a car jerk. The giveaway is timing: gearbox-related jerking happens when pulling away, at the gear change or at low speed, not in neutral.

My car stutters while driving. Is it the gearbox?

Not necessarily. If it also happens when you rev the engine in neutral or while standing still, the cause is on the engine side. If it disappears as soon as you press the clutch or coast, the clutch or gearbox is the more logical suspect.

Why does my car jerk at low speeds but not on the motorway?

At low speed the drive is not yet locked up. A dual clutch has to keep metering between engaging and releasing, and in a conventional automatic the lock-up keeps switching in and out. Wear or outdated adaptation shows up there first. At a constant speed everything is closed and you notice little.

Why does my car judder when I pull away in first gear?

In a manual car this is usually clutch judder: a worn or oil-contaminated clutch plate, a distorted pressure plate or a worn dual mass flywheel. Worn engine or gearbox mounts can feel very similar. In a DSG, the pull-away clutch or its adaptation is the usual suspect.

Can old or wrong transmission fluid cause jerking?

Yes. The fluid determines the friction in the clutch packs and how shift pressure builds up. The wrong specification or heavily contaminated fluid causes harsh or slow gear changes and extra wear over time. A torque converter lock-up judder can even be caused by deteriorated fluid alone.

Can I drive my car if it is jerking?

Gently and for a short distance, often yes, but have it checked soon. Stop straight away with a red warning light, a flashing engine warning light, limp mode, a burning smell or grinding noises. Driving on with a slipping clutch or a misfire turns a smaller repair into a bigger one.

The car hesitates when pulling away and the engine light is flashing. What now?

A flashing engine warning light points to a severe misfire, which can damage the catalytic converter. Drive gently, do not accelerate hard and have the car read out as soon as possible. This is an engine complaint, not a transmission complaint.

Does a dirty air filter make a car jerk?

A badly clogged air filter can starve the engine of air and make it feel flat or hesitant, but on modern cars it is rarely the only cause of real jerking. The airflow sensor, ignition and injectors are more likely. Either way, it is an engine-side cause.

What can I check myself before I call?

Note when it happens, at what speed, in which gear, whether the engine is cold or warm, and whether a warning light comes on. With those answers we can usually tell you on the phone whether it belongs with us or with an engine specialist.

Not sure whether it is the engine or the gearbox?

Describe when the jerking happens: when pulling away, at the gear change, at low speed or only under load. Based on that we will tell you honestly whether it is something for us or whether you are better off with an engine specialist. Book your car in at ATR Transmissies in Montfoort, in the province of Utrecht.