Your car is expected to accelerate in a linear and steady manner, but sometimes something can be wrong and the vehicle can lose power while accelerating.
It could be that the car loses power and then comes back suddenly, or it just doesn’t accelerate like before.
The causes for this can be many, but we will cover the most common and important causes later in the article.
Loss of power during acceleration generally comes in one of two forms; Either the power loss is constant throughout acceleration, or it comes and goes.
The culprit of the problem dictates the type of power loss. For example, bad spark plugs often cause unpleasant acceleration, as the car can jerk when accelerating erratically.
On the other hand, a bad fuel pump could cause the car to accelerate normally until the RPMs go over a threshold, then lose power entirely.
When the car has no power when accelerating, the problem is usually caused by bad spark plugs, fuel filter, fuel pump, sensor problems, or exhaust problems.
To find out why your car loses power when accelerating, read the possible 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’ll also guide you on how to resolve the issue.
Let us begin!
Clogged fuel filter
It’s no surprise that your car needs fuel to keep going and accelerate. The fuel filter ensures that the fuel that reaches the engine is clean and free of debris.
If the fuel filter is clogged, it will be more difficult for fuel to reach the engine. The symptoms can arise even when the car is idling, but problems with acceleration are also common.
If you haven’t changed the fuel filter recently, it’s most likely clogged.
If it causes acceleration issues, it usually also comes with other symptoms like rough idling, trouble starting the engine, stalling, and misfiring.
If you have a fuel pressure gauge available, you can hook it up and see if the problem is the fuel filter or the fuel pump.
A clogged fuel filter will indicate fuel pressure that is low or slowly rising toward a normal level.
A fuel filter is relatively cheap to replace. You can do it yourself, which will cost you between €20 and €60, or take it to a garage to replace it, adding labor costs for half an hour of work.
faulty fuel pump
Like a clogged fuel filter, a bad fuel pump won’t deliver enough fuel to the engine, which can lead to a loss of power 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 increased resistance to pumping the fuel, which can overload the pump.
Another factor that can affect the longevity of the fuel pump is your refueling habits. Fuel not only makes your car run, it also cools the fuel pump.
If you are in the habit of driving low on fuel, you risk premature failure of the fuel pump.
Acceleration problems due to a bad fuel pump are similar to a clogged filter. However, a faulty fuel pump usually has more noticeable symptoms.
Common fuel pump symptoms include rough idling, rough 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 main concern if there is no pressure.
In some cases, the fuel pump itself may not be the problem, but the problem may be with the fuel pump relay, which provides the electrical current for the pump.
It could also be that there is a blown fuse. Therefore, make sure that the fuel pump is receiving electricity. To do this, you can 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
All cars that run on a gasoline engine have spark plugs that eventually go bad.
Spark plugs ignite the fuel-air mixture in the combustion chamber, producing power and consequently making the car drivable.
Bad spark plugs mean that the precise process mentioned above is not working properly, which in turn can lead to various symptoms in addition to loss of power during acceleration.
Spark plugs that don’t work properly also present with misfiring and rough idling.
The easiest way to check if the spark plugs are the problem is to manually check them, which is a relatively simple procedure on most cars. Dirty and burned spark plugs must be replaced.
Due to the tendency for bad spark plugs to cause misfires, in many cases, there will be an OBD2 code that will address a misfire on any of the car’s cylinders.
Replacing spark plugs is not difficult and not as expensive as replacing a fuel pump, for example.
Spark plugs for most cars cost around €10 and take just a few minutes to replace; therefore, replacing spark plugs is not an expensive job.
There is also the possibility that the spark plugs are good but not sparking due to faulty ignition coils.
Faulty mass air flow sensor
The mass air flow sensor is important as it gives the ECU information about the amount of air entering the engine, which is essential for proper air/fuel mixture and therefore combustion.
The mass air flow sensor, or MAF for short, can be repaired by carefully cleaning it with a mass air flow sensor cleaner spray.
In most cases, a faulty mass air flow sensor will return a code on an OBD2 reader, indicating that something is wrong with the mass air flow sensor.
This also means that the check engine light will illuminate.
Except for causing the car to lose power while accelerating, a faulty mass airflow sensor can cause the car to stall, steer rough, and cause poor gas mileage.
Fortunately, repairing the mass air flow sensor is easy and inexpensive in most cases, since all that needs to be done is to clean the sensor.
If it turns out that the sensor needs to be replaced, the cost will be higher. Depending on the car model and who replaces the sensor, you can expect to pay a few hundred euros.
Faulty crankshaft/cam position sensor
The camshaft and crankshaft position sensors are related and both are very important for smooth running of the engine.
The camshaft position sensor sends its data to the ECU, which is essential since the camshaft is responsible for opening and closing the intake and exhaust valves.
Since the engine must work in synchronization, the camshaft plays a vital role together with the crankshaft.
Assume that the intake and exhaust valves open too early or too late.
In this case, the combustion will not take place or it will become inefficient and will cause, among other things, loss of power when accelerating.
Since the camshaft dictates the top of the combustion chamber (ie the valves), the crankshaft is in charge of moving the piston up and down.
Just as the function of the camshaft is essential, so is the crankshaft. The piston must be in the correct position for effective combustion. Failure to do so will result in misfiring and harsh acceleration.
Both sensors cost between €50 and €100 and are generally easy to install. It shouldn’t take more than an hour to replace any of these sensors, although some car models may take longer.
The best way to diagnose the problem is by reading an OBD2 code which should be present if something is wrong with any of these sensors.
exhaust problems
A worn exhaust system
Most people know what exhaust does: it removes what is left of the combustion that has just taken place in the combustion chamber.
Sometimes parts of the exhaust system can get clogged which creates back pressure and consequently can cause problems while driving the car.
As combustion increases during acceleration, so does exhaust gas. If something in the exhaust system is not working properly, it can cause your car to lose power when accelerating.
The exhaust system consists of several parts, which can cause a loss of power when accelerating. Usually the culprit can be a clogged catalytic converter or diesel particulate filter.
A bad catalytic converter almost always indicates another underlying problem that has caused the catalytic converter to clog.
The diesel particulate filter is used in modern diesel cars and can become clogged when driving short distances, and can be resolved by driving a few kilometers on the highway.
faulty turbocharger
Once upon a time, turbochargers were made to make more power in sports cars. While that is still the case, turbochargers have become incredibly effective and efficient for “normal” cars.
This has led many manufacturers to use turbochargers to make smaller, more economical engines while still having enough power.
The turbocharger kicks in after a certain number of RPMs, drawing more air into the engine and power.
Sometimes increased throttle may be noticed as the turbocharger kicks in. On the other hand, a faulty turbocharger will provide poorer performance and acceleration.
If your car isn’t accelerating as usual and it has a turbocharger, it may be to blame.
Unfortunately, turbochargers are expensive, which means that a repair will cost at least €1000, but the cost is usually much higher.
