Cars have become increasingly complex over the years, and with that have been a growing number of symptoms that can mean multiple things. Thankfully, many of these symptoms can be diagnosed and remedied without specialty equipment.
If your car jerks when accelerating, it can be an indication of several current or potential problems. Here we’ll go over the most common culprits and how to fix the issue.
Why Your Car Jerks, Lurches, or Stutters When You Accelerate
When car feels like it’s jerking, surging, bucking, or stuttering after you step on the gas pedal, it’s usually a result of inadequate fuel, air, or spark during the combustion process. However, there are other things that can be the cause. You want to find and fix the problem as soon as possible before it gets worse and costlier to fix.
#1 – Dirty Fuel Injectors
This is a common and annoying problem that can be responsible for a variety of issues. Dirty injectors can cause your car to lose power and make your car jerk while driving at constant speed or from a stop due to frequent engine misfires. You can also hear as the engine stutters from inconsistent fuel intake.
Cleaning the injectors should be done regularly to avoid this problem. Thankfully, this process is quite easy using a fuel injector or fuel system cleaner. However, the injectors can be so fouled up with carbon deposits that even the best fuel injector cleaner may not do the trick. In those cases, you’ll have to either have to take the injectors out to attempt to manually clean or simply replace them.
#2 – Blocked Catalytic Converter
A catalytic converter is responsible for reducing the amount of pollutants that exit out of a car’s exhaust. When the air/fuel mixture in your engine is too rich, a blockage can develop in the catalytic converter over time which disrupts the airflow of the exhaust system.
This can result in stuttering, jerking, and an overall delay in responsiveness whenever you step on the gas. Besides the jerking, other symptoms may include a rotten egg smell (hydrogen sulphide), a drop in the car’s fuel efficiency, and the check engine light may come on.
You may be able to unclog minor blockages by first using a good catalytic converter cleaner. If that doesn’t work, you’ll need to take it to an auto repair shop to fix the problem which will likely include replacement of the catalytic converter.
#3 – Faulty Mass Airflow Sensor
If you notice your car surging forward or jerking at high speeds, it may be due to a mass airflow sensor (MAF) that is failing. Its job is to measure the amount of air entering the engine so it can relay this info to the car’s computer. The computer then instructs the fuel injectors to provide the right amount of fuel at the right time for proper air/fuel mixture.
With a faulty MAF sensor, you may experience your car unexpectedly jerking or surging forward while driving at higher speeds such as on the highway where it would be most noticeable. A check engine light should be present when the mass airflow sensor is bad but you can easily confirm via an OBD2 scanner.
#4 – Bad Fuel Pump or Filter
The cause of your car jerking while accelerating is often a fuel supply issue. When the correct amount of fuel is not being delivered to the engine, it’s often best to start at the beginning. In this case it would be the car’s fuel pump. A failing fuel pump would struggle to keep up with fuel demands and cause your car to jerk or surge forward while driving.
Alternatively, you may have a clogged fuel filter that’s restricting the flow of fuel which also can cause issues as fuel delivery is inconsistent. Replacing the fuel filter is a fairly simple and inexpensive process.
#5 – Dirty Air Filter
As you read this article, you’ll notice an improper air/fuel mixture is often the culprit if your car jerks or sputters when accelerating. Opposite the fuel side of things, is proper air intake. When not enough air makes it into the combustion chamber, you’ll often get the same issues when not enough fuel.
Your car’s air filter is the first line of defense against dirt and other foreign particles. A dirty air filter will allow some particles to get into the engine, which in turn will affect performance and cause jerking.
Check the condition of your air filter. If it’s dirty, replace it. It should only cost $10-$20 and take a few minutes to replace. Alternatively, you can purchase a reusable air filter such as a K&N which allows for future cleanings instead of replacement. A clean filter can drastically improve the lifespan of your car’s engine, including reducing or eliminating the acceleration jerks.
#6 – Faulty Spark Plugs
One of the most common causes is also one of the easiest to identify and fix. During the combustion process, a good spark is needed to properly ignite the fuel in each cylinder. A bad or dirty spark plug can prevent this proper ignition and will cause the engine to misfire. While driving, it feels like your vehicle jerks or shutter when accelerating.
Fixing this problem is as easy as replacing the bad plug. If you don’t remember the last time you replaced your spark plugs, it may be a good idea to get them all changed out. This is a quick and inexpensive repair.
#7 – Moisture Buildup
On colder days, condensation can form under the distributor cap. This mainly occurs when you have the car parked outside overnight. This moisture will cause the engine to misfire, thus your car will jerk when accelerating at low speeds. Luckily, the problem will go away once the water is gone, but repeated moisture buildup can tax your engine over time.
You can avoid this issue altogether by ensuring your car’s parked in a garage or other protected location. A thermal cover can also help reduce the risk of condensation when shelter isn’t an option and you’re expecting colder weather.
#8 – Worn Accelerator Cable
While most cars on the road use drive-by-wire electronic throttle control to accelerate, a physical accelerator cable (or throttle cable) are still found in many vehicles. It acts as a mechanical link between the gas pedal and throttle plate.
Over time, this accelerator cable can wear out. This will cause the car to respond more slowly when you press on the gas and it lurches instead of providing smooth acceleration. You can usually see damage to the cable’s outer coating when examining it, making this problem easy to diagnose.
A damaged cable requires immediate attention, as the car can stop functioning when the cable breaks. Be sure to take it to a trusted mechanic to ensure the replacement is done right.
#9 – Bad Transmission Control Module
If you drive an automatic transmission car and notice your car jerking or bucking right around the time your transmission changes gears, you may have a faulty transmission control module (or solenoid). This part is responsible for gear changes when you accelerate. Gear shifts may be delayed or unpredictable and are often harsh and may feel like the car jerks.
While not a common point of failure, it’s worth considering while you troubleshoot.