Have you ever hit the gas and felt your car jolt forward?
If your car jerks when accelerating, the reason could be anything ranging from engine trouble to transmission issues.
Sounds confusing?
Don’t worry, a trained mechanic can pinpoint the exact cause and repair it properly.
If you’re still curious, we’ll help you understand the causes, how to fix them, and the expected costs. We’ll also share useful tips on how to keep your ride smooth every time.
This Article Contains:
- Car Jerks When Accelerating: 14 Key Reasons
- How Do You Fix a Car That Jerks When You Accelerate?
- Is it Safe to Drive a Car that Jerks While Accelerating?
- How Much Does it Cost to Fix Car Jerking Problems?
- Preventing Car Jerks: 6 Essential Maintenance Tips
Car Jerks When Accelerating: 14 Key Reasons
Here are some of the most common causes your car may jerk during acceleration:
A. Engine, Combustion, and Exhaust System Issues
Problems in the engine’s air, fuel, ignition, and exhaust processes can directly disrupt smooth power delivery, making them common sources of car jerks:
- Worn-out spark plugs: Faulty spark plugs can fail to ignite the air-fuel mixture efficiently, causing misfires. This results in sudden jerks or hesitation when accelerating and can reduce fuel economy.
- Faulty mass airflow (MAF) sensor: A failing MAF sensor sends incorrect airflow readings to the car’s computer, causing the engine to run too rich or too lean. This can lead to jerking during acceleration.
- Vacuum system leaks: Vacuum leaks allow excess air into the intake system, which disrupts the air-fuel mixture and causes engine hesitation while speeding.
- Moisture on the distributor cap: Condensation inside the distributor cap disrupts spark distribution to cylinders, causing engine misfire, rough idling, and jerky acceleration — especially in humid weather.
NOTE: Distributor caps are used only in older vehicles with traditional ignition systems. Most modern cars use electronic coil-on-plug setups instead.
- Damaged cylinders: If a cylinder fails to seal (hold compression) or fire correctly, the car’s engine loses power intermittently, leading to rough acceleration and shaking.
- Dirty air filters: A clogged air filter reduces airflow into the engine, limiting combustion efficiency, which can result in hesitation or jerks. This is most noticeable while driving at high speed or in older vehicles. However, modern engines are better at compensating for this with advanced sensors such as MAF and throttle position sensor (TPS).
- Blocked catalytic converter: A clogged catalytic converter increases exhaust back pressure, restricting engine performance and causing the vehicle to jerk or lose power when you accelerate.
B. Fuel System Issues
When your engine isn’t receiving the right amount of clean fuel at the proper pressure, combustion becomes uneven, producing sudden jerks while accelerating:
- Dirty fuel injector: Clogged fuel injectors restrict fuel delivery, resulting in uneven combustion that leads to hesitation and surges when accelerating. A dirty fuel injector also reduces fuel efficiency because uneven fuel delivery forces the engine to burn more gas to maintain power.
- Damaged gas lines: When a fuel line leaks, proper fuel flow is interrupted, resulting in low pressure and car jerks.
C. Transmission and Drivetrain Issues
The transmission and drivetrain are responsible for transferring engine power to the wheels, and any fault in these systems can cause noticeable shuddering or slipping:
- Worn clutch components (manual vehicles): If the clutch is worn, it can’t maintain a solid connection between the engine and drivetrain. As a result, power delivery becomes irregular, producing jerks whenever you accelerate.
- Low or contaminated transmission fluid: This fluid helps maintain hydraulic pressure and ensures gears engage smoothly. Dirty or insufficient fluid can lead to delayed or rough gear changes, which translates into a jerky ride during acceleration.
- Torque converter issues (automatic vehicles): The torque converter transfers engine power to the transmission in an automatic vehicle. If it malfunctions, the flow of power becomes uneven or interrupted — causing jolts instead of smooth acceleration.
D. Throttle and Acceleration Control Problems
Problems in throttle components can cause delayed gas pedal response or abrupt acceleration jerks.
- Faulty throttle pedal position sensor: A malfunctioning sensor sends incorrect data to the engine control unit about gas pedal position. This may result in power fluctuations, momentary lag, or sharp jolts as you accelerate.
- Damaged acceleration cable: In older vehicles, a sticking, frayed, or damaged acceleration cable could interfere with smooth pedal response and cause sudden jerks when accelerating. However, most modern cars use an electronic “drive-by-wire” system instead of a physical throttle cable.
NOTE: Jerking at low speeds is also a sign of underlying issues in the engine, fuel system, or transmission. If the issue isn’t resolved, the engine may struggle to operate under a heavier load, leading to poor acceleration and increased safety risks.
Now that we understand the issues, let’s explore the solutions.
How Do You Fix a Car That Jerks When You Accelerate?
Resolving a jerking problem typically requires the expertise of a trained specialist who can accurately diagnose the issue and make the necessary repairs. DIY repairs often lead to misdiagnosis and can damage sensitive components such as sensors.
Here’s how an auto repair mechanic will typically diagnose and fix a jerking car:
A. Initial Inspection and Diagnosis
- They’ll open the hood and perform a basic visual inspection for loose wiring, disconnected hoses, fluid leaks, or visible damage.
- Next, connect a diagnostic scanner to check for engine or powertrain fault codes. The codes will indicate what they need to repair.
Once the initial inspection is complete, the mechanic will move on to a detailed, system-by-system evaluation.
B. Engine Combustion and Exhaust System
- Inspect spark plugs and ignition components for wear, buildup, or moisture. They’ll replace faulty spark plugs, a worn ignition coil, or a damaged distributor cap.
- Test engine compression to check for internal engine damage. If compression is uneven or low, they’ll fix cylinder, valve, or head gasket problems.
- Check the air filter for dirt or blockage — replace a dirty filter and repair any damaged intake hoses.
- Inspect the MAF sensor for dirt or faulty readings; clean or replace it if it’s malfunctioning.
- Check the vacuum system for leaks that affect engine performance and replace cracked hoses or faulty gaskets.
- Clean the intake and PCV system to remove heavy buildup. If the PCV valves are clogged, they’ll replace these.
- Check and top off engine oil to maintain proper lubrication.
- Inspect the catalytic converter and exhaust system for blockages. They’ll replace a clogged or failed catalytic converter.
C. Fuel System
- Test the fuel pressure to ensure the fuel pump, regulator, and fuel pressure sensor are functioning correctly. The mechanic will replace a weak fuel pump, a faulty pressure regulator, or a malfunctioning sensor.
- Inspect the fuel injection system for restrictions or poor spray patterns, and replace clogged fuel injectors.
- Check the fuel line and the fuel filter for blockages, rust, or leaks. They’ll replace damaged gas lines or a clogged fuel filter to restore proper fuel flow.
D. Transmission and Drivetrain
- Inspect the transmission system for slipping, delayed shifts, or rough engagement.
- For automatics, check and replace dirty transmission fluid, and repair faulty sensors or internal components as needed.
- For manuals, inspect the clutch for wear and replace it if slipping is detected.
- For automatics, check and replace dirty transmission fluid, and repair faulty sensors or internal components as needed.
E. Throttle and Acceleration
- Inspect the throttle body and acceleration (throttle) cable or electronic throttle system. They’ll clean the throttle body and replace damaged cables or faulty sensors.
- Examine the accelerator pedal sensor and related wiring on electronic throttle systems; replace faulty sensors and recalibrate the throttle system.
- Road-test the vehicle to confirm jerk-free and smooth acceleration.
All of this might seem like a big repair job, and you might feel tempted to delay it.
Well, you should think twice. Here’s why:
Is it Safe to Drive a Car that Jerks While Accelerating?
No, it isn’t.
Problems in the engine, fuel system, transmission, or drivetrain can lead to:
- Sudden loss of power while driving
- Unpredictable acceleration increasing the risk of accidents.
- A minor problem (like a damaged spark plug or clogged fuel injector) escalating into a costly repair.
- Reduced control, especially at high speed or in traffic.
IMPORTANT: Stop driving immediately if the jerking is accompanied by an active check engine light, stalling, burning smells, unusual noises, or difficulty shifting gears. These signs can indicate serious problems with the car engine or transmission.
Bottom line: You shouldn’t ignore even the slightest jerking, whether at high or low speeds. Get your car inspected by a trusted auto repair mechanic right away.
But what does this mean for your wallet?
Let’s find out.
How Much Does it Cost to Fix Car Jerking Problems?
The total repair cost depends on the components that you need to replace or fix. If your check engine light is on, you can expect to pay an additional $50 to $170 for an OBD scan and evaluation.
Here are some common repair estimates (including labor):
- Engine air filter replacement: $55 to $215
- Ignition coil replacement: $85 to $470
- Spark plug replacement: $100 to $400
- Throttle position sensor (TPS) replacement: $150 to $710
- Mass Airflow (MAF) sensor replacement: $250 and $470
- Fuel injector replacement: $335 to $2,000
- Catalytic converter replacement: $450 to $4200
- Fuel pump replacement: $1,100 to $1,300
After the fix, don’t sit back and hope it never happens again. With regular care, you can enjoy a consistently smooth ride.
Preventing Car Jerks: 6 Essential Maintenance Tips
Follow these best practices to keep your car jerk-free and maintain better fuel economy:
- Replace conventional spark plugs every 30,000 to 60,000 miles, and platinum or iridium plugs every 100,000 miles to prevent engine misfire and hesitation.
- Get a transmission fluid flush typically after every 60,000 to 100,000 miles, to avoid shifting issues and jerking.
- Replace the engine air filter every 12 months or 12,000 miles to maintain proper airflow.
- Regularly inspect the health of your catalytic converter and be aware of any unusual noises or odors. Replace it after an interval of 70,000 to 100,000 miles.
- Refuel at reputable stations and add a fuel injector cleaner to minimize injector buildup and blockages. Always use a manufacturer-recommended engine oil for your vehicle.
Restore Smooth Rides with AutoNation Mobile Service
A jerking car can turn a simple drive into a stressful and (even) risky experience.
The good news?
AutoNation Mobile Service can quickly and reliably fix the issue right from your driveway.
We’re available seven days a week, with experienced auto repair technicians and upfront pricing. Moreover, every repair is backed by a 12-month|12,000-mile warranty.
Schedule your service today to keep your car jerk-free and comfortable.