You’re normally used to stepping on the gas pedal, and your car responds by vigorously accelerating as it rapidly shifts through the gears to get you up to speed. However, if you experience sudden jerks and shudders while taking off from a stop or merging onto the highway, it could be a sign of a problem that goes beyond just staying safe on the road.
If your car jerks during acceleration, it’s often because of issues such as fouled spark plugs, fuel injector problems, or a faulty sensor. Any of these can lead to more serious issues that could damage your engine or transmission if left unchecked.
It’s crucial to note that If you feel stutters and shakes while driving, it could indicate one problem, whereas if it’s jerking when idling or applying brakes, it could point to another issue. Therefore, it’s essential to identify the specific circ*mstances under which the jerking occurs to accurately identify the root cause.
To help get you back up to speed and cruising along with confidence, we’re going to have to zoom in on some of the more common reasons why a car jerks when accelerating and what can be done to fix the issues.
Top 9 Causes of Car Jerking During Acceleration
The other symptoms that occur as your car jerks or or lurch forward when you press down on the accelerator pedal will help you dial in what’s causing the problem and what you might be able to do about it. Some of the top causes of jerking acceleration include:
1. Severely Clogged Air Filter
A severely clogged or obstructed air filter can cause an imbalance in the fuel/air mixture that will be more pronounced when you accelerate, causing your car to jerk or lurch forward. This is an easy thing to check, which makes it a simple first place to start troubleshooting why your car jerks when accelerating.
If you haven’t changed your air filter in way too long, or perhaps a mouse got in and made a nest right by the filter, you’ll simply need to replace the air filter and clear away any other obstructing debris.
How to Fix a Clogged Air Filter
If the air filter looks reasonably clean, you can check it off the list and continue delving deeper to determine the cause of jerking acceleration.
2. A Clogged Fuel Filter and/or Bad Fuel Pump
A badly clogged fuel filter and/or a bad fuel pump can also cause a car to jerk during accelerating as the fuel system won’t be able to deliver the correct volume of fuel to maintain consistent internal combustion. A problem like this tends to show up when accelerating hard, as the ECU’s demand for more fuel exceeds what the fuel system can deliver.
If you haven’t changed your fuel filter in over 45,000 miles, or you have a bad habit of running your gas tank to the fuel warning light, chances are good there’s a lot of debris clogging up the fuel filter. When this happens the strain on the fuel pump, can cause it to prematurely fail as well.
How to Fix a Bad Fuel Filter or Fuel Pump
If your car jerks when accelerating is only due to a fuel filter problem, then replacing the filter is relatively easy. If you’re handy, you can do it yourself, or most rapid oil change places can do it for you for around $50.
If the problem includes the fuel pump, then the pump itself will also need to be replaced. This is a project that’s a little too dangerous for a DIY mechanic.
The cost to have a professional mechanic replace your fuel pump will range from $525 to $750.
3. Fouled or Bad Spark Plugs
Fouled or bad spark plugs are another common reason a car jerks under hard acceleration. One or more badlyfouled spark plugsmight fail to fire correctly, causing their power to be absent in the acceleration curve. This jerking motion might be compounded by misfires caused by unburned fuel in the cylinders or the exhaust system.
An engine running hot, poor-quality fuel, and/or a chronically dirty fuel filter can all affect spark plug performance, shortening the lifespan of some or all of your spark plugs. Though most properly maintained spark plugs have an average lifespan of 75,000 to 100,000 miles.
If the check engine light comes on or flashes the car’s computer might throw codes P0301 thru P0308. The last number indicates the cylinder that’s having a problem. Though this could mean spark plugs, ignition coil, or other problems with that specific cylinder’s performance.
How to Fix Bad Spark Plugs
If you pull the spark plug that throws the code and it looks blistered, dirty, or otherwise fouled, you’ll need to completely replace the plug to stop the car from jerking when accelerating.
This is something you can do yourself for around $25 to $30 per spark plug.
A professional mechanic will charge you $40 to $60 per spark plug for a replacement. Usually if one is bad, others are also fouled or it’s wise to replace them, which will save you on labor costs in the long run.
4. Bad Ignition Coils
When your car’s ignition coils fail to provide enough charge to the spark plugs, your car may jerk or hesitate when you try to accelerate. Most modern vehicles have coil-on-plug (COP) ignition coils or ignition coil packs that replace old-fashioned distributor caps.
When the coil fails, the spark plug simply doesn’t fire. This causes a lapse in acceleration that feels like jerking. However, the ECU still delivers the fuel to the cylinder, which often misfires and/or leaves unburned fuel in the exhaust system, which further exacerbates the jerking effect.
With a bad ignition coil, your ECU will also likely throw one or more P0300 codes.
It’s also worth noting that a faulty coil starts to show signs of failure first when it’s under load. You might not notice anything when driving around casually, then when you start towing something or you have to accelerate hard the coil fails, and the car jerks when accelerating. If you keep stepping on it you experience worsening misfires.
When you slow down and idle, the bad coil then causes an intermittent rough idle and lightly will flash or turn the check engine light on.
How to Fix Ignition Coils
If you suspect bad ignition coils may be the culprit behind your car’s jerking, it’s best to have them checked and replaced if necessary.
This is a fix that’s often within the range of what a DIY mechanic can do themselves. Though it can be time intensive to replace multiple coils. So, there’s no shame in having a mechanic replace the bad ignition coils if you don’t feel you’re up to the job, or you don’t have a Saturday to sacrifice.
The cost for a replacement ignition coil ranges between $25 to $50, and you’ll want to replace the spark plug too for another $25 or so.
The cost to have a mechanic replace a single bad ignition coil spark plug averages around $75 to $125 per cylinder.
5. Clogged Fuel Injectors
Using low-quality fuel or a dirty fuel filter can lead to clogged fuel injectors, which can cause your car to jerk when accelerating. When you press the gas pedal, the clogged fuel injector can’t deliver the fuel the engine control unit (ECU) demands in time for the spark plug to fire. This results in hesitation in the engine and possible misfires, which create a jerking motion.
It’s also possible for one or more clogged fuel injectors to be stuck open or closed. This too hampers proper performance which makes the car jerk when accelerating.
A lot of times, when the check engine light comes on the computer will throw codes P0171 and P0174, which indicate it’s seeing a lean condition. Then you most likely will also get P0300 codes associated with the cylinder that has the bad fuel injector.
How to Fix Clogged Fuel Injectors
If one or more clogged fuel injectors are causing your car to jerk when accelerating and the obstruction is minimal, you might be able to clean the injector yourself with a fuel injector cleaning kit. This is something a handy DIY mechanic can do on their own. Though it does require you to remove the clogged fuel injector from the engine.
At this point in the process pouring fuel injector cleaner into the gas tank won’t be enough to unclog the fuel injector enough to stop the car from jerking when accelerating.
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If the fuel injectors are badly clogged, stuck open, stuck closed, or badly fouled they will need to be replaced. This is a project that’s typically beyond what a DIY home mechanic can do.
The cost to have a professional mechanic replace your bad fuel injectors will range between $300 to $800 depending on the make and model of the vehicle as well as the number of injectors that need to be replaced. If more than one injector is bad, the mechanic will rightly advise you to replace all of them. This will save you in total labor costs in the long run.
6. A Bad Mass Airflow Sensor
A bad mass airflow (MAF) sensor can cause imbalances in the fuel/air ratio which manifests as a jerking and stuttering when you press down on the accelerator as well as an overly hard idle. As the sensor and the car’s air handling system continue to struggle you will see increasing symptoms of a problem, and the increased risk of accidentally damaging other engine components.
One of the easiest ways to confirm a mass airflow sensor issue is to hook the car’s computer up to a code reader. It might then throw code P0101 which indicates an issue with your mass airflow sensor itself. You might also see codes P0100-P0109, P0505-P0507, or P2096-P209 which are related to the fuel system running too lean or too rich due to the imbalance in the fuel/air mixture.
How to Fix a Bad MAF Sensor
If the cause of your car jerking when accelerating is linked to a bad MAF sensor, you can usually replace it yourself. The price for the part can vary wildly depending on the make and model, though you should be able to source a replacement for less than $100.
If you aren’t mechanically inclined or don’t have the time to do it yourself a mechanic can usually replace a bad MAF sensor and reset all the related codes for around $180 to $300 depending on the cost of the replacement MAF sensor part.
If you can find a replacement MAF sensor, and you’re a capable DIY mechanic, you can replace the bad MAF sensor with the following steps.
- Step One: Locate the MAF sensor it’s usually between the air filter box and the intake hose.
- Step Two: Remove the electrical connection plug at the side. Some models have tabs you have to depress or squeeze to do this.
- Step Three: Loosen the clamps on the air filter box.
- Step Four: Lift the air filter box up and replace the air filter if it needs it.
- Step Five: Open the part box for the new MAF sensor. There’s often a key or slot card that you can use to slide into the air filter box, which will detach the MAF allowing you to pull it out.
- Step Six: Insert the new MAF sensor and reverse the disassembly steps to complete the installation.
- Step Seven: Clear the codes, start the engine, and go for a test drive to see if the car jerks when accelerating. If not, the replacement MAF sensor likely fixed the imbalance in the fuel/air mixture.
7. A Faulty Accelerator Cable or Throttle Cable
Depending on the age and design of the car, a faulty accelerator cable or throttle cable could also cause a car to jerk when accelerating. These are the electronic and/or mechanical links mechanical link between the throttle assembly and the accelerator “Gas” pedal you step on to make the car go faster.
As time goes on, the cable can start to wear out, causing an intermittent connection between the accelerator pedal and the throttle. This can manifest as the car lurching and sometimes causing the car to jerk during acceleration. As time goes on, the problem can persist even when you’re driving at a consistent speed, which can be very dangerous.
How to Fix a Bad or Loose Throttle Cable
If you have a direct physical throttle cable, you might be able to manually adjust it. This will improve responsiveness and might prevent the car from jerking when accelerating. However, this is usually a short to mid-term fix, and eventually, the cable will likely need to be replaced by a mechanic.
You can adjust a slightly worn-out throttle cable causing the car to jerk when accelerating via the following steps.
- Step One: Locate the throttle cable connected to the throttle body.
- Step Two: Loosen the lock nut just a little bit.
- Step Three: Adjust the barrel-shaped deflection-adjustment nut at the back of the cable until the throttle cable feels tighter and more responsive.
- Step Four: Tighten the lock nut again to secure everything.
This should give you a more responsive acceleration curve and might stop the car from jerking when accelerating.
8. A Catalytic Converter Problem
A full or partial blockage in the catalytic converter can also cause your car to jerk when accelerating. A problem like this essentially prevents exhaust gasses from leaving the car, leading to imbalances in the exhaust manifold which can affect the performance of the engine causing it to run too rich.
If you’re dealing with a total blockage of the catalytic converter, then there won’t be any exhaust coming out of the tailpipe and you might see exhaust seepage in other parts of the lower engine bay or exhaust manifold. If a partial blockage of the catalytic converter is causing your car to jerk when accelerating, you might notice the following symptoms.
- Sluggish engine performance
- Sulfur “Rotten Egg” odor in the exhaust
- Dark smoke
- The car jerks when accelerating
- Excessive heat under the car from the exhaust system
- Check engine light
If the car’s check engine light comes on the ECU might throw a code P0420 which is a general fault in the catalytic converter.
How to Fix a Catalytic Converter Blockage
If a total blockage of the catalytic converter is causing the car to jerk when accelerating, then chances are good you’ll need to replace it. This is an expensive repair that a mechanic will need to perform.
The cost to replace a catalytic converter can range from $900 to $2,500. Though a lot of this cost is the part, you might be able to find a used catalytic converter for your make and model through a salvage auto parts dealer for less.
If the blockage in the catalytic converter is minor, you might be able to clean it yourself with some catalytic converter spray and the following steps.
- Step One: Run your gas tank down to roughly a quarter full.
- Step Two: Add in the specified amount of catalytic converter cleaner.
- Step Three: Drive at non-highway speeds for 15 to 20 minutes to get the catalytic converter cleaner into the fuel and exhaust system.
- Step Four: Fill your tank the rest of the way to full.
- Step Five: Drive at non-highway speeds for 50 to 60 miles, paying attention to the engine performance and any changes in the jerking while accelerating.
9. A TCM Problem
A fault in the transmission control module (TCM) can sometimes cause the car to jerk as you accelerate due to delays in how the automatic transmission changes gears. This is the sort of problem that gradually sneaks up on you slowly getting worse. It often starts to judder around gear changes. Here are some signs of a Bad TCM
- Unpredictable shifting
- Shaking or jerking when shifting into a higher gear
- Trouble downshifting
- Transmission becomes stuck in just one gear
- Poor fuel economy
- Check engine light
If the check engine light comes on, the car’s PCM might throw a code P0700, which is a general code indicating a problem with the TCM.
How to Fix a Bad TCM
A bad TCM is not the sort of thing that a DIY mechanic can fix on their own. You usually need to take the car to a transmission specialist. Unfortunately, like most transmission problems the high cost is directly due to labor.
You can expect a transmission specialist to charge you between $450 to $950 to replace a bad TCM.
10. A Bad Transmission Mount
If you’re experiencing heavy jerks when accelerating, particularly right at the point of a gear change, a bad transmission mount could be the culprit. This is because the transmission mount is designed to carry the weight of the drivetrain and absorb the counter torque and vibration when your car is on the move. Over time, the mount can deteriorate or break down, causing an increasingly physical connection between the often-heavy transmission and the engine itself and leading to the jerking sensation when accelerating.
A bad transmission mount is usually something that happens gradually over time. You shouldn’t see this in a car under 65,000 to 100,000 miles. It’s often due to the wearing down of the heavy-duty rubber as well as corrosion issues on the metal of the mount.
How to Fix a Bad Transmission Mount
Fixing a bad transmission mount that’s causing the car to jerk when accelerating usually requires a transmission specialist to replace the faulty mount. This might include some welding or simply replacing the rubber components.
The cost to replace a bad transmission mount can vary from $250 to $450. This is nicely low for transmission repairs which are typically very expensive.
Frequently Asked Questions
Can I Clean a Dirty MAF Sensor?
If a dirty MAF sensor is causing your car to jerk when accelerating, but you don’t have the funds on hand to buy a replacement sensor, you might be able to get by with cleaning the old sensor. Though to do this you will need a specific MAF sensor cleaner. If you use any other type of cleaner the residue left behind can give the ECU faulty readings.
Is It Safe to Drive a Car That Jerks & Misfires?
Misfires from spark plug problems, a bad ignition coil, or similar faults are related to unburned fuel in the combustion chamber. Not only can these misfires damage your engine, but they can also cause serious damage to the catalytic converter. Sometimes you can drive slowly without misfires, which will be enough to get you home or to the nearest mechanic.
Conclusion
A car that jerks when accelerating is often linked to a serious mechanical fault such as fouled spark plugs, bad ignition coils, clogged fuel injectors, or an airflow issue. These are things that often share similar symptoms such as poor fuel consumption, a rough idle, and potential misfire. They also tend to throw a bunch of general codes that can help you dial in where the problem lies.
Though it’s certainly possible for a bad transmission mount, a TCM problem, or even a dirty MAF sensor to cause a car to jerk when accelerating. Not to mention a partial blockage in a catalytic converter.
Some of these things, like bad spark plugs, ignition coils, or MAF sensors can be fixed on your own for less than $200 and the cost of a full Saturday afternoon. Some of them, like transmission problems and/or fuel injector replacements, or a catalytic converter that needs to be completely replaced should be handled by a fully trained mechanic.
Written By
Jason FarrellJason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.
