If your car is juddering when accelerating, you may feel the vehicle shake, hesitate or jerk instead of building speed smoothly. The problem can come from the engine, fuel system, ignition system, clutch or transmission.
Some causes are relatively simple to fix, while others need proper diagnosis before they become more expensive problems.
Worn Spark Plugs
On petrol cars, worn or faulty spark plugs can cause an engine misfire. This may become more noticeable when you press the accelerator and the engine needs to produce more power.
You may also notice rough idling, poor acceleration or an engine warning light.
If the spark plugs are due for replacement, fitting the correct specification can restore smoother engine operation. (RAC)
Blocked Fuel Filter
A restricted fuel filter can reduce the amount of fuel reaching the engine. This may cause hesitation, poor acceleration or juddering, particularly when the engine is under load.
If your car has also developed starting problems or feels weak when accelerating uphill, the fuel system should be checked.
Dirty or Faulty Fuel Injectors
Fuel injectors control the amount of fuel delivered to the engine. If they become dirty or develop a fault, fuel delivery may become inconsistent.
This can result in hesitation, rough running and juddering when accelerating.
Don’t automatically replace the injectors based on the symptom alone. Proper diagnosis can determine whether cleaning, testing or replacement is actually required.
Clutch Problems
If you drive a manual car and the juddering happens mainly when pulling away or changing gear, the clutch could be involved.
A worn clutch, uneven clutch components or contamination can cause the vehicle to judder as the clutch engages. A slipping clutch may also cause the engine RPM to rise without a matching increase in road speed. (RAC)
Low or Contaminated Transmission Fluid
Automatic and some other transmission systems depend on the correct fluid level and condition.
Low or contaminated transmission fluid can contribute to poor or jerky acceleration and gear changes. The correct fluid specification is important because using the wrong fluid can create additional transmission problems. (RAC)
Dirty Air Filter
The engine needs a suitable supply of air for proper combustion. A heavily clogged air filter can restrict airflow and contribute to poor engine performance and juddering during acceleration.
This is worth checking if the vehicle is regularly driven on dusty roads or has gone a long time without servicing.
Faulty Ignition Coil
A failing ignition coil can cause an intermittent engine misfire, particularly when the engine is under acceleration.
The car may feel as though it is briefly losing power before recovering. A diagnostic scan can help identify misfire-related faults, although the underlying cause still needs to be confirmed.
Blocked Catalytic Converter
A restricted catalytic converter can interfere with exhaust flow and cause poor acceleration.
You may notice that the car struggles to gain speed when you press the accelerator. Other symptoms can include reduced engine performance and an engine warning light. (RAC)
Engine Mount Problems
Engine mounts hold the engine securely in position. If a mount becomes worn or damaged, you may feel excessive vibration or judder, particularly at low engine speeds or when accelerating.
A mechanic can inspect the mounts for movement, damage or deterioration.
Problems With the Fuel Pump
A weak fuel pump may struggle to deliver enough fuel when the engine demands more fuel during acceleration.
This can cause hesitation, stuttering or loss of power. If the problem becomes worse when accelerating hard or climbing a hill, the fuel delivery system should be investigated.
Poor-Quality or Contaminated Fuel
Bad or contaminated fuel can affect combustion and fuel delivery.
If the juddering started shortly after refuelling, particularly from an unfamiliar fuel source, tell the mechanic when describing the problem. Contaminated or incorrect fuel can cause hesitation and jerking during acceleration. (RAC)
What Should You Check First?
Don’t immediately start replacing expensive parts.
A mechanic can begin by checking:
- Engine fault codes
- Spark plugs and ignition coils
- Fuel filter and fuel pressure
- Fuel injectors
- Air filter
- Engine mounts
- Clutch operation
- Transmission fluid
- Sensors and air intake
- Exhaust restrictions
The exact checks will depend on whether the car judders at low speed, high speed, when pulling away or only during gear changes.
Can You Drive a Juddering Car?
It depends on how severe the problem is.
If the car is only experiencing a minor intermittent hesitation, arrange an inspection rather than ignoring it. If it is violently shaking, losing significant power, overheating, producing unusual smoke or showing a flashing engine warning light, stop driving when it is safe and have the vehicle checked.
A car that suddenly loses power during acceleration can become particularly risky when joining busy roads or overtaking.
Check the Car Before a Long Journey
If your car is juddering when accelerating, get the problem investigated before starting a long interstate trip.
A small fuel or ignition fault may be relatively straightforward to repair, while continuing to drive with a serious engine, clutch or transmission problem can make the eventual repair more expensive.
For travel planning, vehicle logistics and transport coordination, Travo.ng can help you organise your journey while your vehicle is being properly checked and maintained.
