Your car is expected to accelerate linearly and steadily, but sometimes something may be wrong, and the vehicle may lose power while accelerating.
It may be that the car loses power and then comes back suddenly, or it simply does not accelerate as it used to.
The causes for this can be many, but we will cover the most common and important causes further down in the article.
Power loss during acceleration usually presents in one of two ways; either the power loss is consistent throughout the acceleration, or it comes and goes.
The culprit of the problem dictates the type of power loss. For example, bad spark plugs usually cause an unpleasant acceleration as the car may jerk while accelerating unevenly.
On the other hand, a bad fuel pump could make the car accelerate normally until the RPMs go over a threshold to then lose power completely.
When the car has no power when accelerating, the problem is most commonly due to bad spark plugs, the fuel filter, the fuel pump, sensor issues, or problems with the exhaust.
To find out why your car is losing power when accelerating, read through the potential causes below and see if they match your car’s symptoms.
If it turns out that one of the listed culprits is the cause of your symptoms, we will also guide you on how to resolve the issue.
Let’s get started!
Table of ContentsShow
Clogged Fuel Filter
It does not come as a surprise that your car needs fuel to keep going and accelerating. The fuel filter ensures that the fuel that reaches the engine is clean without debris.
If the fuel filter is clogged, the fuel will have a more challenging time reaching the engine. Symptoms may arise even when the car is idling, but problems with acceleration are also usual.
If you have not changed the fuel filter recently, the chances are that the fuel filter is clogged.
If it causes acceleration problems, it usually also comes with other symptoms such as rough idle, problems starting the engine, stalling, and misfires.
If you have a fuel pressure gauge tester available, you may hook it up and see if the fuel filter or the fuel pump is the problem.
A clogged fuel filter will indicate a fuel pressure that is low or is slowly rising toward a normal level.
A fuel filter is relatively cheap to replace. You can either do it alone, which will cost you about $20 to $60, or take it to a shop to replace it, adding labor costs for half an hour of work.
Bad Fuel Pump
Similar to a clogged fuel filter, a bad fuel pump will not deliver enough fuel to the engine, which can lead to power loss when accelerating, among other symptoms.
The fuel pump is closely related to the fuel filter, as a clogged filter can cause the fuel pump to go bad. This is because there is a greater resistance to pump the fuel, which may overwork the pump.
Another factor that can impact the longevity of the fuel pump is your refueling habits. The fuel not only makes your car drive, but it also cools down the fuel pump.
If you have a habit of driving with low fuel, you risk making the fuel pump prematurely go bad.
Acceleration problems due to a bad fuel pump are similar to a clogged filter. However, a bad fuel pump usually comes with more noticeable symptoms.
Common fuel pump symptoms include rough idle, jerky acceleration, and trouble starting the engine.
Like the fuel filter, a great way to test the fuel pump is to use a fuel pressure gauge. The fuel pump should be your primary concern if no pressure is present.
In some cases, the fuel pump, per se, may not be the problem, but the problem may be with the fuel pump relay, which provides the pump’s electrical current.
It may also be that there is a fuse that is blown. Therefore, make sure that the fuel pump receives electricity. To do this, you may use a voltmeter.
Replacing a blown fuse or fuel pump relay is considerably cheaper than replacing the fuel pump, which costs around $500 with labor and parts.
Bad Spark Plugs
Every car powered by a gasoline engine has spark plugs that eventually go bad.
The spark plugs ignite the fuel/air mixture in the combustion chamber, producing power and consequently making the car able to drive.
Bad spark plugs mean that the precise process mentioned above does not work correctly, which in turn may lead to various symptoms other than power loss during acceleration.
Spark plugs that do not work properly also present misfires and a rough idle.
The easiest way to check if the spark plugs are the problem is by manually checking them, which is a relatively simple procedure in most cars. Dirty and burnt spark plugs are up for replacement.
Due to the inclination for bad spark plugs to cause misfires, in many cases, there will be an OBD2 code that will address a misfire in any of the car’s cylinders.
Replacing spark plugs is not difficult and is not as expensive as replacing a fuel pump, for example.
Spark plugs for most cars cost around $10, and replacing them takes only a few minutes; therefore, replacing spark plugs is not an expensive job.
There is also a possibility that the spark plugs are fine but do not produce sparks due to bad ignition coils.
Faulty Mass Airflow Sensor
The mass airflow sensor is important as it gives information to the ECU on how much air is getting into the engine, which is essential to have an appropriate air/fuel mixture and hence combustion.
The mass airflow sensor, or MAF for short, can be fixed by cleaning it carefully with a mass airflow sensor cleaner spray.
In most cases, a faulty mass airflow sensor will throw a code on an OBD2 reader, stating that something is wrong with the mass airflow sensor.
This also means that the check engine light will be illuminated.
Except for making the car lose power while accelerating, a bad mass airflow sensor may make the car stall, drive roughly, and cause bad gas mileage.
Luckily, fixing the mass airflow sensor is easy and cheap in most cases, as all that must be done is to clean the sensor.
If it turns out that the sensor must be replaced, the cost will be higher. Depending on the car model and who replaces the sensor, you may expect to pay a few hundred dollars.
Faulty Cam/Crank Position Sensor
The camshaft and crankshaft position sensors are related and are both very important for making the engine run smoothly.
The camshaft position sensor sends its data to the ECU, which is essential as the camshaft is responsible for opening and closing the intake- and exhaust valves.
As the engine must work synchronously, the camshaft plays a vital role together with the crankshaft.
Suppose the intake and exhaust valves open too early or too late.
In that case, the combustion will either not take place or become ineffective and cause, among other things, power loss when accelerating.
As the camshaft dictates the upper part of the combustion chamber (i.e., the valves), the crankshaft is responsible for moving the piston up and down.
Just like the camshaft function is essential, so is the crankshaft. The piston must be in the correct position for effective combustion. If not, misfires and rough acceleration will occur.
Both sensors cost about $50 to $100 and are usually easy to install. It should not take more than one hour to replace either of these sensors, although some car models may need more time.
The best way to diagnose the problem is by reading an OBD2 code that should be present if something is wrong with either of these sensors.
Most people know what the exhaust does – it eliminates what is left of the combustion that just took place in the combustion chamber.
Sometimes parts of the exhaust system can be clogged, leading to backpressure and consequently may cause problems when driving the car.
As the combustion increases during acceleration, so do the exhaust gases. If something in the exhaust system does not work correctly, it may cause your car to lose power when accelerating.
The exhaust system consists of multiple parts, which can cause power loss when accelerating. Usually, the culprit may either be a clogged catalytic converter or a diesel particulate filter.
A catalytic converter that is bad almost always indicates another underlying problem that has led to the catalytic converter clogging.
The diesel particulate filter is used in modern diesel cars and can be clogged up when driving short distances, and it may be resolved by driving a few miles on the highway.
Once upon a time, turbochargers were made to generate more power in sports cars. While that is still the case, turbochargers have become incredibly effective and efficient for “normal” cars.
This has led to many manufacturers using turbochargers to make smaller and more economical engines while still having enough power.
The turbocharger spools up after a certain number of RPMs, introducing more air into the engine and power.
An increased acceleration can sometimes be noted as the turbocharger spools up. On the other hand, a faulty turbocharger will provide worse performance and acceleration.
If your car is not accelerating as usual and has a turbocharger, it may be the culprit.
Unfortunately, turbochargers are expensive, meaning that a fix will cost at least $1000, but the cost is usually much higher.