25 Reasons Why Your Car Jerks When Accelerating (and Under Other Conditions)
Most drivers know their cars inside and out. Therefore, it is not surprising that most vehicle owners identify driving problems as soon as they occur. Few of these driving problems are more annoying and difficult to identify than those that can best be described as jerky, stuttering, or hesitation.
It can be extremely infuriating to deal with a problem that suddenly appears without any logic. Fortunately, the root causes of such problems are rarely difficult to fix and are fairly easy to identify once you know where to start looking. Below are the most common causes of a car jerking under acceleration and other driving situations.
Under Acceleration (at low speeds)
1) Faulty Ignition Components
For a gasoline engine to run efficiently, it must distribute a spark to each cylinder at the right time. If your vehicle’s ignition system is having problems, you will often experience jerking or hesitation, especially at low speeds. The most common causes of such problems are worn or fouled spark plugs, damaged spark plug wires, and external arcing ignition coils.
2) Fouled Injectors
Internal combustion engines also require an adequate supply of fuel to operate properly. When an engine’s fuel injectors become clogged, fuel flow can be restricted in one or more cylinders. In this case, you may experience uneven acceleration with or without the engine check light coming on.
3) Restricted intake air volume or faulty MAF sensor
Engine combustion also relies on the intake of fresh, oxygen-rich air. In situations where sufficient air flow to the vehicle’s intake tract is prevented, jerking can occur under load.
In these situations, a dirty or clogged air filter is often the culprit. Similarly, a faulty mass air flow sensor can cause similar issues as it prevents the vehicle’s PCM from determining the correct intake readings.
4) Clogged catalytic converter
The catalytic converter in your vehicle is responsible for breaking down harmful exhaust gases that are emitted as a by-product of combustion. However, if the catalytic converter is clogged, it can prevent exhaust gases from being expelled, affecting the performance of your engine. This often leads to a sluggish acceleration. A clogged catalytic converter often causes a rotten egg-like smell.
5) Throttle Cable Wear
If your vehicle is equipped with a cable-operated throttle body, typical wear on the cable can be the cause of your vehicle’s acceleration problems. When a metal throttle cable begins to fray, it can temporarily catch on the casing, causing excessive resistance.
6) Ignition System Issues
When accelerating, a jerky sound or hesitation can occur if there are numerous irregularities in the engine’s ignition system. These include issues with the spark plugs, ignition wires, ignition coils, ignition coils, and ignition distributor. A momentary spark failure causes incomplete combustion, resulting in an abnormal jerking of the engine.
7) Fuel System Issues
When an engine is starved of fuel, it will not perform optimally, especially when accelerating or frequently at high speeds. Common causes of such issues are weak fuel pumps, clogged fuel filters, and dirty fuel injectors.
8) Restricted Air Intake
During high acceleration, a vehicle’s engine consumes a lot of air through the intake to enable combustion. When this airflow is blocked, serious drivability issues usually occur. Such issues are usually most likely due to a dirty air filter, but damaged intake ducts are also a major cause.
9) Engine Misfire
The engine may stall, jerk or stutter while driving for the same reasons as when accelerating. The most likely cause of such a problem is a misfire in one or more cylinders. The cause of a misfire is usually a problem with the ignition system or fuel system. To determine the cause of the misfire, you need to check whether each cylinder is firing properly and verify the correct fuel pressure.
10) Mass Air Flow Sensor Failure
A failed mass air flow sensor is another common cause of driving problems that occur while driving. If the engine’s PCM does not receive valid MAF sensor feedback, it cannot calculate fuel delivery as intended.
11) Damaged Clock Spring Wiring
If the twitching only occurs when the cruise control is on, a damaged clock spring may be the cause of the problem. A clock spring is a coiled electrical connection wire that attaches to the steering wheel of a vehicle. This special connection wire facilitates the operation of accessories attached to the steering wheel, which is constantly turning. If the clock spring wears out, the wiring in the cruise control circuit may temporarily break.
12) Warped Rotor
Disc brakes use friction between a set of brake pads and a corresponding rotor to slow the movement of the vehicle. Unfortunately, these components do not last forever and replacement is inevitable.
As the discs become thinner, thermal shock from overheating or cooling too quickly can cause a jerky feeling when you press the brake pedal.
13) Air-in ABS systems
Modern vehicles use ABS modules to modify brake pressure during emergency braking to prevent skidding. However, the ABS system relies on the absence of air to operate properly.
14) Low Transmission Fluid Level
Automatic transmissions rely on a proper supply of transmission fluid to allow the torque converter to operate. If your vehicle’s transmission fluid is low or in poor condition, you will often experience hard or delayed shifts. Operating your vehicle’s transmission for extended periods with a fluid level lower than the specified level can cause permanent damage.
15) Sensor or Solenoid Failure
Automatic transmissions use a series of sensors and solenoids to maintain proper shift points. Damage to any of these sensors or solenoids will most likely result in delayed or erratic switching. Often, such issues will occur most frequently when shifting from 1st to 2nd gear or when shifting into overdrive.
16) Vacuum Issues
Many older automatic transmissions were equipped with a vacuum modulator valve. When the vacuum supply to this valve was damaged or the valve itself failed internally, it often caused many switching-related problems.
17) Damaged or worn internal components
Both automatic and manual transmissions are prone to internal wear over time. Aging can cause components to fail, resulting in a variety of driving problems. Automatic transmissions are prone to clutch packing issues, while manual transmissions are prone to clutch, synchronizer, or gearbox failure.
18) Universal Joint Play
If your vehicle suddenly jerks when you shift into reverse, it could be due to worn drivetrain components. All vehicles have some play when engaging reverse gear. However, severely worn universal joints can exacerbate this condition, causing a noticeable jerky feeling when the vehicle first moves in reverse.
19) Transmission Related Issues
Older transmissions may jerk or hesitate when engaging reverse gear. This can have a variety of causes. The transmission itself may be low on fluid, or the magnets in the valve body may be stuck. Or there is a slight chance that the transmission may have developed internal wear.
20) Moisture Under the Distributor Cap
Your engine’s distributor is responsible for sending a spark to each spark plug wire at the right time. However, a cracked distributor cap or a faulty distributor cap gasket can lead to water ingress. Water getting under your car’s distributor cap often causes misfires and rough idling. This type of problem often occurs during cold weather or after heavy rain.
21) Worn or damaged spark plugs or ignition wires
In addition, other components of the ignition system can cause your vehicle to feel jerky when idling. This is most commonly seen when spark plugs are worn or fouled, or when spark plug wires are damaged.
22) Restricted fuel flow
Without a continuous supply of fuel, your engine cannot function optimally. Therefore, any problem affecting the vehicle’s fuel system can lead to problems related to abnormal idling. The root cause of such problems could be dirty injectors, a faulty fuel pressure regulator, a clogged fuel filter, etc.
23) IAC Valve Failure
When idling, the vehicle’s throttle valve closes and the air distribution is transferred to the engine’s idle air control valve. This valve allows a small amount of air to pass through the throttle plate to maintain the engine idling. If the IAC valve fails or becomes clogged, it can cause an abnormal idling or a rough idle.
24) Vacuum Leaks
If any type of air entering the engine intake is not metered, it can cause serious problems with idling. This is most commonly referred to as a vacuum leak. Vacuum leaks often occur in hoses, intake runners, and intake seals (intake manifold gasket, throttle body gasket).
25) IAC Valve Failure
When the air conditioning compressor is on, it puts a lot of strain on the vehicle’s engine. To compensate for issues related to stalling and poor performance, many vehicles utilize idle air control to increase the air available for combustion. A failed idle control valve can cause air restriction, rough idling and poor acceleration.