Car Not Accelerating? Here are 9 Reasons Why

Find out if you’re overpaying on car insurance using our cost calculator! Save money by comparing quotes from over 30 of Canada’s top insurance providers!

The best part? It’s FREE!

car not accelerating

You’re driving along, listening to your favourite tunes, but then you notice that your car begins to slow down.

You step on the gas pedal a few times, but it doesn’t change anything. 

The car won’t accelerate!

There are many different reasons why this could be happening, so what do you do? You can try giving it a pep talk:

“You can do it.”

“You were made for this!”

However, unless you’re driving KITT, it’s unlikely to do anything.

In this blog post, we’ll discuss what exactly is wrong with your car when it won’t accelerate.

How does a car accelerate?

Before we can investigate what might cause your car not to accelerate, it’s worthwhile to know how a car gains speed.

The throttle pedal connects directly to your car’s engine which regulates the amount of air entering the intake manifold via a throttle body for fuel injection or a carburetor.

The air combines with gas via a fuel rail and fuel injectors or a carburetor, then introduced with a spark fed by spark plugs resulting in combustion, which forces the engine’s pistons down to turn the crankshaft.

As the throttle pedal is lowers, more air enters the intake manifold to be combined with even more fuel to rotate the crankshaft faster. This is your engine “revving” as the crankshaft RPM rises.

A car that has trouble accelerating can be very dangerous. A lack of power could mean an inability for you to merge onto the freeway or make a turn at high speeds, putting yourself and others in danger.

Combustion engines are designed to have fuel delivered and dispersed away from the vehicle. Many components work together in order for this process, which includes combustion elements as well sensors on your car’s engine system – when there is a failure within one these functions it can cause acceleration problems with vehicles!

It’s not only inconvenient, but it’s also dangerous if you can’t build up speed when climbing uphill or merging onto a busy road or highway.

Why is my car not accelerating?

If you’re having trouble with your car’s acceleration, it could be any one of these problems that might affect how easily the engine can gain speed.

The following are what we believe to be the most common:

Mass Air Flow Sensor Malfunctioning

mass air flow sensor

The mass airflow sensor regulates how much air gets mixed with gas before being introduced into your engine’s intake manifold, and it helps control acceleration and fuel economy. It’s attached to your inlet air cleaner. Since the function of the airflow sensor is to measure air mass that is flowing into air intake, a clogged or bad mass airflow sensor could send the wrong data to the engine ECU for calculating the air-fuel mixture. If your mass airflow sensor malfunctions, your car may experience poor acceleration.

Oxygen Sensor Malfunction

oxygen sensor monitors

The oxygen sensors help what is called the “closed-loop” system of fuel management by monitoring how much gas you are using and what kind of emissions it’s putting out. If it detects that your emissions are too high or if there is a drop in what’s called the “oxygen pulse,” then this can cause issues with slow acceleration even when your gas pedal is fully pressed down.

Throttle Position Sensor Malfunctioning

throttle position sensor

The throttle position sensor is a device that measures the engine speed and detects the throttle valve opening angle. If the throttle position sensor malfunctions, the engine speed cannot be controlled through the use of the accelerator pedal, and it will rise or fall without your pressing on it.

Clogged Fuel Filter

dirty fuel filter

A clogged fuel filter can be a problem because it forces the car’s engine to work harder in order for your car to accelerate, which puts strain on the entire system and makes acceleration difficult if not impossible. If this is the case, you should replace your fuel filter ASAP.

Dirty Air Filters

dirty air filter

If your air filter is clogged up with dirt and debris, it could affect how much airflow gets into the engine’s intake manifold, which will have an effect on acceleration. However, if there are multiple problems that need addressing, then having a dirty air filter is likely not what causes your car to not accelerate.

Timing Belt Issues

timing belt

A timing belt is what connects the engine’s crankshaft to its camshaft(s) at different points in time. The timing belt works with your car’s valves, pistons, and spark plugs to make sure that everything moves together correctly during combustion inside of the cylinders. If it breaks or slips off of either one of these, then the valves and pistons could collide with each other, and the engine will not be able to produce enough power for acceleration.

Defective Fuel Pump

fuel pumps

It is possible that a defective fuel pump may cause the car to not accelerate or it could affect your gas pedal’s ability to send an appropriate signal. The function of a fuel pump is to pull fuel from the gas tank to the engine via fuel lines. If the fuel pump becomes clogged or malfunctions, it won’t be able to supply fuel to the injectors resulting in poor acceleration, sputtering, or stall-outs.

Faulty Fuel Injector

fuel injector

A car’s fuel injectors are designed to deliver precise amounts of gas into the combustion chamber. If you have an older car, there is a chance that the fuel injectors are clogged. With these systems, it can be difficult to make sure all of those tiny passages stay free from any obstructions, making automatic delivery impossible and could lead to reduced engine performance, issue with pressure levels during startup, and give your engine trouble accelerating.

Clogged or Leaky Vacuum Hoses

Inside the intake manifold, air pressure relative to external pressure is known as engine vacuum. The engine vacuum will be at its greatest at idle or with the throttle closed (foot off the gas).

The vacuum hoses allow the engine to receive extra air and release exhaust from your car’s combustion chamber. If the vacuum hoses are clogged or have leaks in them, this could cause your car not to accelerate.

Should I ignore acceleration issues?

Acceleration difficulties are not nearly as dire as many people believe. A check engine light accompanies most issues, so you should have them addressed. Acceleration issues aren’t something that go away on their own if you ignore them. If you don’t do anything to correct the problem, problems will only get worse. Most automobile owners lack the knowledge and ability to work on cars, so what should you do? The answer is simple: find a professional mechanic.

Sign up for our Newsletter

Recent Articles