14 Reasons Your Car Jerks When Braking
In today’s fast-paced world, our vehicles are essential. So, when they cause problems, it’s worrisome. Nothing is more unpleasant than an unexpected jerk when braking, slowing down, or stopping.
Let’s break down the possible causes of this annoying problem into whether you’re braking, coasting, or actually coming to a stop, because it’s something no one wants to experience again.
What Causes Your Car to Jerk When Braking
It’s not uncommon for drivers to experience a “jerky” sensation when braking. While such issues are by no means uncommon, they still require a great deal of attention to remedy the situation.
Here are some of the most common reasons why your vehicle jerks when you press the brake pedal:
1) Deformed Rotors
Deformed brake rotors are the most common cause of a jerky feeling when braking your vehicle. Over time, your vehicle’s brake rotors can become distorted due to overheating, excessive wear, or rapid cooling.
This deformation is felt when your vehicle’s brake pads press against the affected brake rotor, causing a noticeable pulsation.
2) ABS Activation
Operating your vehicle’s ABS (Anti-lock Brake System) valve will cause a noticeable jerking noise when stopping.
This effect is not cause for concern, especially if you are trying to stop suddenly in wet conditions. However, if your vehicle’s ABS system begins to activate during random stops, further diagnosis is required.
3) Brake Booster Damage
Failure of the vacuum brake booster is also a possible cause of vehicle vibration when braking.
A car’s brake booster works by operating a diaphragm under vacuum when the car’s brake pedal is pressed. If this membrane is damaged in any way, it can cause shuddering when braking.
4) Stuck Brake Calipers
Severely stuck brake calipers can also cause your vehicle to jerk when braking. These bumps and jumps are caused by the binding that occurs when your vehicle’s brake pads clamp onto their corresponding rotors.
In some cases, you may also hear a rattle noise in this condition.
5) Worn Steering/Suspension Bushings
A typical vehicle uses a variety of bushings (control arm bushings, shock absorber bushings, rack bushings, etc.) to dampen vibrations in the front end of the vehicle. However, these bushings tend to wear down over time, causing a noticeable increase in vibrations that were previously damped. This condition is most noticeable when braking.
What causes a car to jerk when braking
Your vehicle may jerk when braking, even if the application of the brakes is undefined. The cause of this abnormal vibration should be identified and addressed as soon as possible.
Below are some of the most common reasons why your vehicle may jerk when braking to a stop:
6) Transmission Issues
A jerky sensation when braking to a stop often indicates a transmission issue such as a faulty valve body or TCM.
This is typically true for both automatic and manual transmissions, which will try to adjust their gear ratio and speed to suit the situation. Further diagnosis is required to uncover the full extent of such an issue.
7) MAF Sensor Failure
It is not uncommon for the engine to jerk when the vehicle is decelerated due to a faulty Mass Air Flow (MAF) sensor. The Mass Air Flow sensor provides feedback to the engine’s ECM/PCM about the amount of air flowing through the intake tract. This feedback is used to calculate the engine’s fuel adjustments in real time. However, presenting inaccurate data can result in combustion anomalies.
8) Damaged Ignition Coil
The engine’s ignition coil delivers a spark to each individual cylinder at the right time. However, when ignition coils begin to fail, misfires occur at low speeds, often accompanied by jerking or skipping.
Such issues can also occur at higher speeds, but jerking during acceleration is much more common as the relative engine load is greatly reduced.
9) Sticking Throttle
In some cases, a stuck throttle on your engine can cause a jerky noise. The throttle valve acts as a metering device for all incoming air being introduced into the engine’s intake manifold for combustion.
When the throttle is stuck, or for some reason does not move to the desired position to meet the engine’s demands, there is often some hesitation involved.
10) Vacuum Leak
Another common cause of a vehicle jerking under braking is a severe vacuum leak.
Older vehicles often required engine vacuum for many important functions, including EGR operation. To make matters worse, leaks in the vehicle’s vacuum system can cause severe but erratic misfires, often only felt when slowing down to a complete stop.
What Causes Your Car to Shake When Stopped
Although this is less common than the situation above, your vehicle may also shake noticeably when stopped. For many people, this is a cause for concern and can cause anxiety until corrective action is taken.
Here are some of the most common reasons your vehicle may shake while stopped.
11) Ignition System Issues
If your vehicle twitches or shudders at idle while stopped at traffic lights, it is often due to one or more issues with the ignition system. Some of the most common of these problems include worn spark plugs, old spark plug wires, faulty ignition coils, etc.
On older vehicles, such issues were often caused by worn or damaged distributor caps or rotor knobs.
12) Fuel Delivery Problems
A miss detected while idling is often caused by an issue within an engine’s fuel system. A vehicle can experience a host of fuel system-related issues, including a clogged fuel filter, defective fuel pressure regulator, or malfunctioning injectors.
The bulk of these issues seem to be most easily noticed when sitting idle in a parking lot, or at a stop light.
13) Inefficient Air Delivery
An internal combustion engine requires a steady supply of clean intake air at all times, to facilitate proper operation. If an engine is starved for air at any point, combustion efficiency and overall performance plummet, typically causing a severe misfire.
This misfire can be easily detected at idle, or during periods of low engine load. Problems of this nature can be attributed to throttle body defects or the prolonged use of a dirty or clogged air filter.
14) Vacuum Leaks
Vacuum leaks are among the most common causes of erratic idle, due to their allowance of unmetered air into an engine’s intake tract. This air is not accounted for by an engine’s ECM/PCM, therefore leading to a notably lean condition.
As a result, combustion efficiency is significantly stifled, and engine performance takes a nosedive of unmatched proportions.
