Why Is My Car Struggling to Accelerate?
Charlotte Phillips, 13 days ago
3 min read
- Diagnostic
FixMyCar discusses why cars might struggle to accelerate.
It's frustrating when your car struggles to accelerate, especially if you've got somewhere important you need to be. This guide explains why it might be happening and what you can do about it.
Contents
Why doesn’t my car accelerate?
Imagine a weight has been added to your car, pulling you back despite no apparent cause. That's what a loss of acceleration feels like - your vehicle isn’t gaining the speed it used to when you put your foot down.
Several things could cause this problem; the most common reasons are listed below.
1. Malfunctioning MAF sensor
The mass air flow (MAF) sensor is located between the air filter and intake manifold. It monitors the amount of air entering the engine, allowing the ECU to create the ideal air-fuel ratio for performance.
When it becomes clogged or fails, the result is often an acceleration lag because the sensor can't detect the correct air density, meaning fuel doesn't reach the combustion chamber quickly enough.
2. Blocked fuel injectors
Blocked or dirty fuel injectors often cause a loss of acceleration because the engine isn't getting the fuel it needs to perform optimally. One possible solution is to run a cleaning additive through the fuel system, which may solve the problem.
However, the injectors may be blocked due to an old fuel filter, which can no longer prevent contaminants from reaching them.
Fuel filters need replacing every 20,000-100,000 miles; you can find the maintenance intervals for your car's filters in the vehicle handbook. Even if you successfully clean your injectors with a fuel additive, the same thing will happen again without a new filter.
3. Oxygen sensor problems
The oxygen sensor in your car helps to regulate the air-fuel ratio going through the engine and sends this data to your car’s computer system. If the sensor becomes damaged or malfunctions, the ECU can't regulate the air-to-fuel ratio. As a result, your vehicle might struggle to pick up speed or hesitate as you accelerate.
Replacing an oxygen sensor costs £188.80 on average, according to our data.
4. Catalytic converter failure
The catalytic converter is essential because it acts as a defence against air pollution from our vehicles. It exchanges the harmful substances in your car’s exhaust fumes, such as nitrogen oxides, for less toxic substances, like water vapour.
Check out our ultimate guide to exhausts for more information.
While a catalytic converter should last around ten years, it can become blocked, overheated, or generally damaged, causing acceleration problems for your car. When the airflow into the engine is restricted, you'll notice a drop in performance and speed. Other symptoms may include excessive heat and a rotten egg smell.
A catalytic converter replacement costs £433.80 on FixMyCar.
5. Damaged inlet manifold gasket
You can find the inlet manifold gasket between the inlet manifold and engine block. It's a mechanical seal that prevents air, oil and coolant from mixing. When worn or damaged, it can result in a lean air-fuel mixture, which often leads to a lack of power and engine misfiring.
6. Turbocharger issues
Turbochargers force more air into the engine by compressing it. The amount of fuel injected into the engine increases correspondingly, giving it more power.
Issues with the turbocharger can sometimes lead to a loss of acceleration, such as damaged compressor vanes, a faulty solenoid valve or loose boost hoses.
The following signs indicate a problem with the turbocharger:
Slower, louder acceleration
Difficulty maintaining high speeds
The average price of a turbocharger replacement or repair job booked through FixMyCar is £663.95.
Looking for affordable car repairs or maintenance? FixMyCar can help you find the right garage at the right price.
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