car shakes when accelerating

Most Likely Causes

1. 1

   Engine Misfires

   Engine misfires occur when one or more cylinders fail to ignite fuel properly, causing uneven power pulses that make your car shake when accelerating. This is typically caused by bad spark plugs, ignition coils, or fuel injector problems. A misfire is one of the most common reasons for acceleration shaking.

   Older vehicles with high mileage are more prone to misfire issues.

2. 2

   Worn Motor Mounts

   Motor mounts secure the engine to the chassis and absorb vibration. When they wear out or tear, the engine rocks excessively during acceleration, causing noticeable shaking throughout the cabin. This type of shake is often felt more in the steering wheel and is worst during hard acceleration.

   Manual transmissions are especially affected since motor mounts work harder to control engine movement.

3. 3

   Transmission Issues

   Transmission problems such as low fluid, slipping gears, or solenoid failures cause jerky acceleration and violent shaking. When the transmission struggles to engage or shift smoothly, the power delivery becomes erratic, making the car shake when accelerating. This often worsens at higher RPMs.

   Automatic transmissions are more commonly affected than manuals due to fluid-dependent shift quality.

4. 4

   Worn Suspension Components

   Damaged control arms, ball joints, or sway bar links can cause vibration under acceleration loads. Worn suspension bushings fail to isolate engine vibration, allowing excessive movement in the drivetrain that translates to shaking. This is amplified when turning while accelerating.

   Vehicles with higher mileage and rough driving conditions wear suspension faster.

5. 5

   Fuel System Problems

   A clogged fuel filter, failing fuel pump, or dirty fuel injectors restrict fuel flow, causing lean fuel mixture and cylinder misfires. Poor fuel delivery results in uneven combustion and shaking when the engine demands more fuel during acceleration. Fuel system issues often trigger Check Engine lights.

   Vehicles using low-quality gasoline are more susceptible to fuel injector carbon buildup.

6. 6

   Damaged Drive Axles or CV Joints

   Cracked or worn CV joints and axle shafts transmit power unevenly to the wheels, causing vibration especially during acceleration. Front-wheel-drive vehicles are most affected. A clicking sound during turns combined with shaking during acceleration suggests CV joint failure.

   Front-wheel-drive cars experience more CV joint wear than all-wheel-drive vehicles.

How to Diagnose It

1. 1

   Check for Stored or Pending Diagnostic Codes

   Use an OBD-II scanner to read the vehicle's computer memory. Connect the scanner to the diagnostic port under the steering wheel and retrieve any stored or pending codes. Codes starting with P0 (powertrain) directly indicate what system is failing and guide your next diagnostic step.

   Tool: OBD-II diagnostic scanner

2. 2

   Inspect Spark Plugs and Ignition Coils

   Remove each spark plug and visually inspect for wear, carbon buildup, or damage. Compare the gap to manufacturer specs using a spark plug gauge. Test ignition coils with a multimeter for proper resistance, or swap suspected coils to another cylinder and see if the shake moves. Fouled or gapped plugs are the easiest misfire cause to fix.

   Tool: Socket set, spark plug gauge, multimeter

3. 3

   Test Motor Mounts Under Acceleration

   With the vehicle parked and in gear on level ground, gently apply throttle while an assistant watches the engine from the side. Excessive engine rocking (more than 1 inch of movement) indicates worn mounts. Have them check each mount for tears, cracks, or separation from the engine block.

4. 4

   Check Transmission Fluid Level and Condition

   With the engine warm and running, pull the transmission dipstick and inspect the fluid color and smell. Low, dark, or burnt-smelling fluid indicates transmission problems. Top off if low, then test drive to see if shaking improves. Some modern vehicles require professional scanning to check transmission pressure.

   Tool: Transmission dipstick or diagnostic scanner

5. 5

   Perform a Visual Suspension and Drivetrain Inspection

   Safely lift the vehicle on jack stands and physically inspect all suspension joints, control arms, and sway bar links for play, cracks, or separation. Spin each wheel and listen for CV joint clicking or grinding. Check for any loose heat shields or exhaust components that could rattle during acceleration.

   Tool: Jack, jack stands, creeper

How to Fix It

• Replace Spark Plugs and/or Ignition Coils

  Remove old spark plugs and coils, clean the wells, and install new ones using the correct part numbers and gap specifications. This is the most common fix for cars that shake when accelerating due to misfires. Reset any related diagnostic codes and test drive to confirm the shake is gone.

• Replace Motor Mounts

  Support the engine weight with a jack, unbolt worn mounts from the frame and engine, then bolt new mounts in place. Ensure the engine sits level and centered before fully tightening bolts. This eliminates excessive engine rocking and vibration during acceleration.

• Service Transmission System

  Shop recommended

  Start with a transmission fluid and filter change if the fluid is dark or low. If shaking persists, a more serious transmission issue may require professional solenoid repair or internal servicing. Some transmission shops offer fluid flushes with additives to improve shift quality.

• Repair or Replace Fuel System Components

  Replace clogged fuel filters and test the fuel pump pressure with a gauge. Clean fuel injectors chemically or replace them if clogged. A fuel system cleaning additive can also help restore proper flow and reduce misfire-related shaking.