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Top 11 Main Causes Of A Car Losing Power When Accelerating


Many consumers first notice a problem with their vehicles when the car accelerates poorly, stutters, or the engine will not start at all. If you have a car losing power when accelerating check the obvious items such as sufficient fuel in the gas lines, clean air filters, and plugged exhaust pipes first.

More serious causes of power loss may include:

  • Sensors malfunction – camshaft, oxygen, crankshaft, and more
  • Actuators malfunction – spark plugs, ignition coil, fuel pump, injectors
  • Mechanical malfunction – compression, air filter, fuel filter, clogged exhaust.

Consumers should not hesitate to have their car’s engine checked by a professional mechanic to avoid causing serious damage to the engine or placing your vehicle in a dangerous situation on the road. Here is some more detail about potential problems that could cause your car to accelerate poorly.

Top 11 Causes of Car losing Power When Accelerating or While Driving

Car losing power when accelerating

Your car may lose power for many different reasons. Before heading off to the mechanic, check your air filter and exhaust pipe to ensure they are not blocked in some manner. If your car is losing power while driving and the car jerks when accelerating then make sure the following parts function properly:

  • Low Compression
  • Clogged Fuel Filter
  • Dirty Air Filter
  • Clogged Exhaust Pipe
  • Camshaft Position Sensor
  • MAF Sensor Malfunction
  • Oxygen Sensor
  • Faulty Fuel Injectors
  • Bad or Weak Fuel Pump
  • Clogged catalytic converter
  • Bad Spark Plugs
  • Bad Ignition Coil

All of the above mentioned can be affecting your engines performance, and they related to loss of power when a car accelerates.

1. Low Cylinder Compression (Gas & Diesel Engine)

Low compression in one or more cylinders can cause a multitude of problems, including less power delivered to the crankshaft. As the piston moves up the cylinder towards the spark plug or injectors, the gases inside the cylinder are compressed until it reaches a predefined pressure.

An electric spark delivered by the spark plugs ignites the gases and pushes the piston back down and turning the crankshaft in the process. Cylinders with low compression due to bad valve seats or worn piston rings will not deliver the full power they are designed to deliver.

You may not notice if one cylinder is experiencing low compression. However, if more than one is not delivering full power, drivers can experience poor acceleration and may not achieve top speed.

2. Clogged Fuel Filter (Gas & Diesel Engine)

A fuel filter sits on the fuel line between the injectors on your engine and the fuel pump. The task of the filter is to filter out any impurities that may be in the gasoline. These impurities can appear if your fuel tank is rusty, or the fuel itself was not as clean as it should be. Once the fuel filter becomes clogged, insufficient fuel will be delivered to the injectors, causing poor fuel to air mixtures and delivering less power.

A fuel filter is a relatively easy, inexpensive repair, and should be replaced to avoid damage to the engine. Damage from a lean fuel to air mixture and contaminants entering the engine injectors and cylinders can damage components.

3. Bad Air Filter (Gas & Diesel Engine)

Vehicle air filter replacement by mechanic

Air filters are designed to filter out bugs, dust, and other debris before the air enters the engine internal combustion chamber. Any debris, especially dust particles, can severely damage the engine by causing lower compression. As air filters become increasingly dirty and clogged with debris over time, there is a reduction in the level of air that can pass through the filter.

If insufficient air reaches the engine, the air to fuel mixture will not be ideal, and the engine could produce less power. A poor air to fuel mixture can also increase the pollutants that exit the engine, potentially impacting catalytic converters. Air filters are relatively inexpensive and easy to exchange.

4. Clogged Exhaust Pipe (Gas & Diesel Engine)

The exhaust pipe consists of pipes, a catalytic converter, and a muffler. Most people only see the tailpipe at the back of the car. The catalytic converter removes pollutants generated during combustion, and the muffler reduces the amount of noise from the engine. If you inadvertently backed into something, it is possible to clog the exhaust pipe.

Also, the exhaust system can also become clogged if the muffler or catalytic converter malfunctions. In all of these situations, the engine would not mix the right amount of air-fuel, causing a power reduction. Check your tailpipe to confirm a normal amount of exhaust gases.

Cleaning a clogged catalytic converter is an option to evaluate when the problem relies in the exhaust pipe system.

5. Camshaft Position Sensor Malfunction (Gas & Diesel Engine)

The job of the camshaft position sensor is to provide the exact location of the camshaft to the ECM or engine control module. The ECM uses this information to manage the fuel injection and the ignition sequence.

If the camshaft position module is malfunctioning, the fuel may enter the cylinder at the wrong time, and the ignition may also ignite at the wrong time.

The result can be lower power levels, increased fuel consumption, and even engine backfires in severe situations. The ECM should generate error codes for a mechanic to read. The ECM will also illuminate the check engine light on the dash in this situation.

6. MAF Sensor Malfunction (Gas Engines)

The Mass Air Flow sensor monitors the air flowing into the engine and reports this information to the ECM, Engine Control Module.

The ECM takes this information along with other data and calculates the ignition timing, the amount of fuel needed to provide the perfect air to fuel mixture required to deliver the appropriate power levels to the drive shaft.

A malfunctioning MAF (Mass Airflow Sensor) usually causes poor performance from the engine, which may cause it to stall or burn a high or low fuel to air ratio. The engine may stall or hesitate while accelerating, and it reflects directly with a huge amount of loss in power.

7. Oxygen Sensor Malfunction (Gas Engines)

The o2 sensor checks the ratio of air and fuel mixture and provides the information to the ECM. The ECM is responsible for ensuring the correct amount of air and fuel enter the cylinder and ignition timing.

Air intake varies a great deal based on temperature, altitude, air pressure, and more. If the sensor malfunctions, the check engine light may illuminate, the gas mileage may decline, the engine runs rough, or the engine fails an emissions test, and power levels decline.

The ECM will be unable to calculate the correct fuel to air mixture and control ignition and timing with a bad o2 sensor reporting incorrect data.

8. Bad Fuel Injectors (Gas & Diesel Engine)

The ECM tells the fuel injector when to inject fuel into the cylinder and how much fuel should be injected based on load, oxygen levels, and all of the sensor data the ECM receives.

A faulty fuel injector may be caused by a broken wire or injectors that have become dirty over time. They may not open fully or close fully or open at the correct instant.

As a result, a poor fuel-air mixture is delivered to the cylinder, and the engine generates insufficient power. All of the fuel injectors should be checked by a mechanic and replaced as needed.

9. Bad or Weak Fuel Pump (Gas Engines)

The fuel pump delivers fuel from your car’s gasoline tank to your engine at the appropriate pressure. A fuel pump may be failing or not working at all leaving your engine starved for fuel.

With no fuel, your engine will not operate, while one that is still delivering fuel at lower pressure may cause your engine to deliver lower power, stutter, or turn off at the most inopportune time.

Fuel pumps can fail due to age, perhaps a bad electrical connection, or even clogged due to sludge from the gas tank. A mechanic will need to replace the fuel pump.

10. Bad Spark Plugs (Gas Engine)

Mechanic replacing bad spark plugs in a car

Spark plugs generate a spark at the right time to ignite the air-fuel mixture in the cylinder. The engine control module manages when the spark ignites the air-fuel mixture. Spark plugs deteriorate over time due to corrosion and combustion materials coating the plugs. They should be replaced or cleaned and the gap adjusted if needed to proper specs.

Occasionally the spark plug wires can also deteriorate due to corrosion and arcing. At the very least, check the condition of the wires and replace them if required. A bad wire may cause the plug not to fire at all or burn properly leading to partially burned fuel exiting the exhaust pipe.

11. Bad Ignition Coil (Gas Engine)

The ignition coil transforms 12 volts to over 20,000 volts and delivers the electricity via the spark plug wires to the spark plug. Your car’s standard electrical operating system works on 12 volts DC. A spark plug requires at least 20,000 volts to generate a spark and ignite the fuel-air mixture.

The coils of the ignition system must also deliver the electrical charge at the correct moment to fire the spark plug as the cylinder reaches the top of its cycle. A bad ignition coil that does not deliver the electrical charge needed to one or more spark plugs will cause your engine to lose power, and poorly burned fuel may also exit your exhaust pipe.

Tips & Summary

Diagnosing an engine that is performing poorly can be challenging, and specialized equipment is often needed. Your check engine warning light may be illuminated, indicating that the engine control module has identified a problem with the engine or its components.

A mechanic can use an electronic reader to read the error code. The trouble codes can identify the malfunctioning component, and make the appropriate repairs if you have a vehicle losing power.

These problems can also be related to an overheated cooling system. We recommend regular car maintenance like checking the engine oil to detect any coolant mixture that can cause an engine power loss. It is incredible how getting an oiled change can help you find the solution to lost power and acceleration in a car.

You can now identify some of the reasons your car is losing power and what’s causing the engine to under perform. So, you are now prepared and know what to do when you have a car not accelerating when you press down on the gas pedal.

Last Updated on: January 26, 2023

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