9 Causes of a Car Losing Power When Accelerating

(Updated on August 16, 2021)

Have you ever been in a situation where you’re driving your vehicle and as you accelerate, you start to lose power instead of gain power? Sometimes this can be attributed to your car not having enough fuel.

However, it can also be attributed to numerous other causes related to mechanical problems, malfunctioning sensors, and/or malfunctioning actuators. Sometimes the cause can be different if you have a diesel engine versus a gasoline engine, but there are also a lot of similar causes between the two engines. You just have to know what to look for.

Top Reasons Your Car Loses Power While Driving

Here are nine of the most common causes for a vehicle to lose power when accelerating.

1) Bad Spark Plugs

best spark plugs

The internal combustion engine of your vehicle relies on the spark plugs for transmitting the electrical signal from the ignition coils to the internal combustion chamber. Once that happens, an electric spark ignites the mixture of fuel and air.

Therefore, if you have faulty spark plugs that cannot transmit this electrical signal, then the performance of your engine will weaken and you won’t be able to accelerate as fast. It will eventually get to the point where it won’t accelerate at all.

Related: Best Spark Plugs for Better Performance and Gas Mileage

2) Bad Fuel Pump

bad fuel pump

The fuel pump is how fuel inside of the gas tank is brought to the engine for combustion. The fuel pump also regulates the pressure of the fuel as it is transferred in order to accommodate the engine’s needs.

A faulty fuel pump would cause an inconsistent supply of fuel to be transferred. This will result in poor engine performance and acceleration.

3) Bad Fuel Injectors

fuel injectors

A car engine depends on its fuel injectors inside of the fuel system. A fuel injector is responsible for actually spraying the fuel, brought in by the fuel pump, into each cylinder.

Obviously, if the fuel injector goes bad or is clogged, then it won’t be able to adequately spray fuel into the engine. This would result in the engine being unable to produce enough power to accelerate.

Often, running a fuel injector cleaner through your system can clear up a clogged injector but other times, replacement may be necessary.

4) Low Level of Compression

low compression causes

The internal combustion process relies on strong cylinder compression for the vehicle to generate enough power to accelerate. If there is a low level of compression due to bad seals or other issue, there will be a low level of power being generated by the engine.

5) Exhaust Pipe is Clogged

car exhaust smoke

The exhaust pipe is comprised of two filters called the catalytic converter and the muffler. The catalytic converter reduces the pollution produced by the exhaust fumes. The muffler reduces the noise produced.

If either of these filters or the exhaust pipe were to have something clogging them, then it would impair the engine and cause the power it generates to be reduced. Before replacing a clogged or dirty catalytic converter, it’s worth using a good catalytic converter cleaner first.

6) Dirty Air Filter

clogged air filter

When the internal combustion chamber mixes air and gasoline to produce power, the air first goes through an air filter before it enters the chamber. This filter helps keep out all the outside debris and bugs from the chamber.

If you were to have a clogged or dirty air filter, then not enough air would be getting into the engine for optimal combustion. Thus you will have a lack of power when trying to accelerate.

7) Faulty Ignition Coil

bad ignition coils

The ignition system has ignition coils which convert 12 volts of power from your battery into the 20,000 volts of power needed to ignite the engine. If you were to have a bad ignition coil, then the mixture of fuel and air inside the engine would not be ignited adequately. This means you would lose power as you put your foot on the gas pedal.

There are over a dozen reasons why you would have trouble accelerating but these are just some of the most common causes. You could also have a failing turbo charger, bad EGR valve, or a faulty injection pump delivery valve among others.

Regardless of what the undermining cause is, get your vehicle to a repair shop as soon as you notice it’s consistently losing power when accelerating. You don’t want to let this problem go on for too long or else it could cause further issues.

More importantly, it could be putting your life and the lives of other drivers at risk when you’re on the road.

8) Engine Knock

four stroke gasoline engine

Engine knock, also known as predetonation or “pinging” is uncontrolled fuel ignition inside the combustion chamber.

Combustion engines are precisely timed so they can maximize power and efficiency. If the fuel burns before it’s supposed to, the piston may not be in the correct position in the cylinder. This could cause loss of power and even catastrophic engine damage. 

9) Clogged Catalytic Converter

The catalytic converter is responsible for cleaning exhaust gases, converting toxic gases such as NOx and carbon monoxide into less toxic molecules.

A restriction in the catalytic converter would prevent the exhaust gases from exiting properly. In extreme cases, this can even cause a fire so this issue should be addressed as soon as possible. 

2 thoughts on “9 Causes of a Car Losing Power When Accelerating”

  1. I have a 1994 Oldsmobile Cutlass Supreme S 3.1 and I believe that I have a bad gas filter, which was last changed in March 2019 & it was running fine on the morning of Saturday, July 11th, but during the evening I’ve noticed a loss of power even with my foot on the floor it was going very slowly, but when I took my foot off the gas and put it back on, it was going faster. Could it also be an air filter that’s NOT seeded in right and also the top of the air filter box isn’t on tight.The car does starts ok

    • Unless the air filter was somehow blocking airflow, I don’t think that’s the problem.

      How are your spark plugs? I would start with the simple stuff first. Make sure your plugs and wires are good.

      Also check the condition of the plugs to see if your car has been running rich or lean. Plugs in a lean cylinder look white and burnt. Plugs in a rich cylinder look black and are sometimes wet. If your air fuel ratio is off, you may have another issue and further diagnosis is needed.


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