Car Repair and Maintenance

Car Struggles to Accelerate [Causes and How to Fix]

Car struggles to accelerate

Not only is it inconvenient when your car struggles to accelerate but could also cause expensive damage if left unrepaired. Typically, this indicates a variety of concerns such as a faulty oxygen sensor, bad throttle position sensor, faulty carburetors, etc. Well, you may not be the technician to fix your car but this publication explains what could be causing your car’s acceleration problem as well as how you can fix the issue.

Car struggle to accelerate

Car struggles to accelerate

Loss of acceleration manifests as the car is not gaining the same speed when the accelerator is pressed as it formerly did. As mentioned earlier, a car struggling to accelerate could be caused by various reasons explained below.

  1. Malfunctioning mass air flow sensor

The mass air flow (MAF) sensor is located in the engine of your car and is responsible for communicating the exact amount of gasoline flowing through the engine. This maximizes the performance of your car by monitoring the exact airflow through its engine.

When the MAF Sensor becomes clogged or malfunctions, it cannot accurately measure the airflow through the engine, causing the engine ECU to receive incorrect data. This can cause engine damage, and one of the primary symptoms is that the car struggles to accelerate and shakes.

How to fix

You can fix a clogged or malfunctioning mass air flow sensor by following these steps below:

  • Choose a mass air flow sensor cleanser and clean the sensor, as this may alleviate the symptoms if the issue is contamination in the system.
  • After blowing out the intake tube, replace the air filter to prevent dust from clogging the system.
  • Replace your car’s mass air flow sensor if nothing else works.
  1. Dirty fuel filters

One of the primary reasons a car struggles to accelerate is dirty or blocked fuel filters. If a car’s fuel filter is clogged, the engine will not receive the proper amount of fuel, resulting in diminished acceleration. Usually, when this is the case, the car struggles to accelerate from stop, as well as in first gear.

How to fix

It is vital to maintain the cleanliness of fuel because even a small amount of dirt can restrict fuel flow, interfering with the fuel’s system.

Due to restricted fuel flow, a clogged filter also makes it difficult to start the car. Ensure that you frequently clean the filter.

You don’t need to bother bringing your car to the repair shop because the process of cleaning dirt may be done quite effortlessly. There are multiple ways to clean the gasoline filter, allowing you to prevent dirt from adhering.

  • Identify the fuel filter
  • Make certain no fuel is exposed to spray
  • Prepare a container under the filter
  • Start cleaning the fuel filter
  • Tap all the circles on the fuel filter surface of the car
  • Spray again and dry
  • Install the filter back
  • Replace the filter if necessary
  1. Faulty timing chain

The timing chain is one of the most important components of your car’s engine. As such, even a minor slip can immediately cause acceleration issues.

On average, you need to replace timing chains between 80,000 and 120,000 miles, per Cloyes. Nevertheless, minor timing chain problems can occur in between and can be significantly less expensive to repair.

How to fix

In addition to maintaining an up-to-date knowledge of car maintenance, drivers can take care of their timing chain by ensuring that their engine oil is routinely topped off and changed as advised by their mechanic or owner’s handbook. This will ensure that the timing chain is adequately lubricated and will not degrade rapidly.

Unfortunately, your car may have a timing chain that is prone to breakdown. If this occurs, you should contact a professional mechanic to replace it.

  1. Damaged acceleration cables

When you have bad or damaged acceleration cables, your car can also struggle to accelerate. This cable connects the gas cable to the throttle plate on the engine. The cable pulls the throttle open when the gas pedal is depressed, allowing the car to accelerate.

How to fix

Follow the steps below if the cable breaks at the end of either side of the cable.

  • Remove the side that is intact or not broken.
  • OR remove the cord from the accelerator pedal. Typically, it is a “Z” joint that can be removed from its attachment point.
  • OR disconnect the throttle cable from its attachment to the carburetor’s throttle arm.
  • Check the broken end and measure its length. If it has broken less than an inch from the end, you can repair the throttle cable.
  • When removing the cable, carefully ease it out of its covering sheath.
  • Remove one inch of sheath.
  • Apply WD40 oil to the sheath until it begins to run out of the opposite end.
  • If the broken end of the cable is frayed, cut the frayed ends using sharp wire cutters and remove the frayed portion carefully.
  • Return the cable into the sheath until each end protrudes.
  • Determine which end of the cable is damaged.
  • Using two pairs of needle tip pliers, bend the end carefully into the same “Z” form as the damaged portion.
  • Reconnect the throttle cord and test its functionality.
  1. Faulty carburetors

The carburetor is responsible for regulating the ratio of air to fuel before it enters the engine. When the carburetor is damaged, not only will your car struggle when accelerating, but its overall performance will also suffer.

How to fix

Being able to repair your own carburetor does not require you to be a skilled technician. If your car struggles to accelerate or the engine is spending excessive amounts of petrol,  you can restore them to working order by completing the procedures below.

First and foremost, you will require these materials:

  • A carburetor repair kit
  • A carburetor cleaner
  • Screwdriver
  • Box wrenches
  • Pin punch
  • Hammer
  • Full line clamp
  • Torque wrench
  • Water
  • Towels


  • Remove the carburetor.
  • Separate the float-type carburetor from the engine.
  • Examine the carburetor
  • Examine the air-fuel ratio screws
  • Reassemble the carburetor
  • Finally, attach the carburetor and air cleaner assembly.
  1. Moisture on the distributor cap

Due to moisture accumulation on the distributor cap, you may experience jerky acceleration if it is snowing outside. This generally occurs when you park your car outside during the winter. Thus, a cold location causes car struggles to accelerate when cold.

How to fix

Follow these steps below to clean the moisture on the distributor cap:

Label the spark plugs cables to help you bring them back in the same sequence. You can then take the cables carefully out from the distributor cap.

Remove the two screws on the side of the cap and try to remove it by gently lifting it up.

Using a mild abrasive, rub the contact terminals to remove any carbon buildups and oxidation on the metal terminals. Oxidation may impede or weaken contact.

Spray some contact cleaner on the interior contacts of the distributor cap.

If you have a compressed air source, apply the compressed air through the cap. This will assist it to dry faster. You can also use a clean rug and slowly rub it until the cap is completely dry.

When you are convinced that you completed the job right assemble back. Place the distributor caps in position. Connect back the spark plug wire correctly in the order that you marked earlier in step 1.

  1. Oxygen sensor difficulties

The oxygen sensor in your car monitors the air-to-fuel ratio in the engine and transmits this data to the car’s computer system. If this sensor becomes damaged or malfunctions, the engine will be unable to regulate the correct air-to-fuel ratio. As a result, your car struggles to accelerate uphill and the engine runs rich or lean. It might also not be able to gain speed or stall when accelerating if this sensor becomes faulty.

Read also: Eyes on your O2 sensor codes

How to fix

The oxygen sensor is not a device requiring frequent maintenance. They do fail occasionally, however, causing the check engine light. Determine the reason of the check engine light by employing an OBD2 scanner such as FIXD. If the issue code reflects faulty oxygen sensor data, it is time to replace the sensor.

  1. Failed catalytic converter

The catalytic converter is crucial because it functions as a barrier against the air pollution caused by cars. The catalytic converter converts toxic compounds, such as carbon monoxide, in your car’s exhaust fumes into less hazardous substances, such as carbon dioxide and water vapor.

The catalytic converter might become clogged, overheated, or otherwise damaged, which is likely to result in acceleration issues for your car, even though they should typically survive for roughly 10 years. In addition to car struggling to accelerate and shaking, you may also notice excessive heat and a burning odor coming from your car if the catalytic converter fails.

How to fix

You can try using fuel additives, removing and cleaning the catalytic converter, and driving your car aggressively to get a high operating temperature. Otherwise, you need a replacement cat converter.

  1. Bad timing belt

The timing belt is responsible for coordinating the valve movement in the engine. If it is not functioning properly, the engine will be unable to function properly, and the car will drive slowly. The timing belt is connected to the camshaft and the crankshaft and helps to manage the pistons of the engine. While the camshaft controls the opening and closing of the valves, the timing belt controls the process timing. Thus, if the timing belt’s alignment is off, your car will struggle to accelerate.

How to fix

You may have to replace the belt. The estimated cost to replace a timing belt will range between $300 and $500. (more for larger cars, trucks, and SUVs). Typically, the timing belt itself costs less than $50.

  1. Bad throttle position sensor

A malfunctioning throttle position sensor may also contribute to sluggish acceleration. This sensor is responsible for signaling the engine’s fuel consumption. If it is not functioning properly, the engine will not be able to use the necessary amount of fuel, which will slow down the car.

How to fix

Have a mechanic check it out and replace the problematic sensor if necessary.

While replacing your sensor entirely may be the most effective way to prevent future problems, certain problems can be quickly resolved by reprogramming or fixing your sensor. This step may be required when installing a new sensor.

  1. Limp mode

If the car’s ECU detects a malfunction, limp mode and the check engine light will be activated. It is a safety function that reduces your car’s speed. To determine what caused this mode, take your car to a professional mechanic.

How to fix

After around 30 seconds, you could be able to reset the car by turning it off and on again. If the warning lights fade and the car returns to regular operation, it may have been a transient malfunction. However, pre-system checks may cause limp mode to activate as soon as the car is restarted, or the problem may reappear after a period of driving.

If it immediately returns to Limp mode, it is recommended to schedule a comprehensive inspection. If the problem is minor, you can either drive it to your garage or have it rescued.

  1. Ignition system difficulties

The ignition system produces a spark to ignite the mixture of air and fuel. A filthy spark plug or damaged ignition wires restrict the combustion chamber from consuming all of the fuel. This results in the loss of acceleration-required power.

Frequently Asked Questions

What causes a car to lack acceleration?

There are a variety of reasons why a car struggles to accelerate including a clogged fuel filter, a faulty throttle position sensor, an oxygen sensor malfunction, etc. If you’re unsure what’s causing the acceleration issue, we recommend having a professional examine your car.

Why doesn’t my car accelerate when I press the gas pedal?

It could be something as simple as a dirty air filter, or the gas tank could be nearly empty. The throttle position sensor, the fuel injectors, or the ignition system could be at fault. Additionally, a dirty throttle body may prohibit the engine from receiving sufficient air.

What causes a car to have slow acceleration?

Common causes of slow car acceleration include a clogged fuel filter, a faulty throttle position sensor, or an oxygen sensor malfunction. In addition, the timing belt may be worn, preventing the engine from accelerating correctly.


Immediately have your car evaluated if you are experiencing acceleration issues to determine the cause. Get it fixed to guarantee safety. Do not attempt to repair the car yourself; instead, hire a professional. Always include add-on coverages with your policy to protect against repair costs.

Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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