Having a car that won’t accelerate is a stressful experience. In this situation, your car might start right up and run fine for a short period. Then, when the time comes to get up to speed, there’s no power.
The good news is that many solutions to this issue are relatively simple, although there is always the chance that you have a significant problem in your engine, too.
Here’s a look at some things that cause a car to lose power when accelerating and what you can do about them.
How a Car Accelerates
First off, it’s a good idea to learn how a car accelerates. Vehicles operate using an internal combustion engine, which takes a combination of fuel and air, compresses it, and ignites it inside a specialized chamber.
As this fuel burns, it pushes harmful exhaust out the tailpipe while using the combustion reaction’s energy to power the car. There’s also an electric component to this process, as the engine control module (ECM) monitors the process using a series of sensors.
When any of these components – fuel, air, engine, electrical – malfunction, it could lead to acceleration problems. Some causes are more common than others, so here’s a look at some of the issues you could encounter.
Common Causes of a Car Losing Power When Accelerating
Your car can lose power when you try to accelerate for many different reasons. The first step in the repair process is determining the root cause of the issue to start on the recommended fix.
Fuel System Problems
Your vehicle’s fuel system needs to be functional for the car to run correctly. When the fuel isn’t flowing between the tank and the engine, problems are sure to follow.
Clogged Fuel Filter
One of the most common reasons for acceleration problems is a clogged fuel filter. This filter acts as a barrier between impurities in your gasoline or diesel and the engine.
When the filter is clogged, these contaminants can pass into the engine and prevent the car from accelerating.
Luckily, a clogged fuel filter is a straightforward repair, as all you have to do is replace it.
Bad Fuel Pump
A car’s fuel pump moves fuel from the gas tank to the engine. This pump ensures that this fuel delivery occurs at the right pressure, maximizing the engine’s performance.
When the fuel pump isn’t working, the fuel might not arrive at the correct pressure, leading to acceleration and other performance issues.
Clogged Fuel Injectors
Over time, your fuel injectors can get dirty, preventing fuel from flowing into your engine at the optimal rates. When this occurs, your car could struggle to reach high RPMs, leading to acceleration issues.
RPMs measure how many times the engine’s crankshaft makes a full rotation per minute and how many times the pistons go up and down in their cylinders.
When the fuel injectors are clogged, the engine doesn’t get enough fuel to maximize its revolutions per minute, and acceleration problems can follow.
Blocked Diesel Particulate Filter
Because diesel doesn’t burn as cleanly as gasoline, it leaves behind soot. Therefore, modern diesel cars have a diesel particulate filter that collects this soot and stores it, reducing the vehicle’s emissions.
If you have a diesel car, you’ll have to clean or replace your filter regularly because failing to do so could cause acceleration problems.
Exhaust System Issues
A car’s exhaust system is responsible for directing toxic hydrocarbons away from the vehicle’s passengers. However, when the system isn’t functioning, it can cause performance issues, too.
Clog in the Exhaust
Clogs can appear in your exhaust system over time, leading to performance issues. These clogs occur for various reasons, including debris from the road getting into the system. There could also be a leak somewhere in your exhaust system in this scenario.
Often, the clog will occur in your car’s catalytic converter or particle filter. The catalytic converter works by converting harmful emissions into water vapor and releasing them as exhaust. When this component is clogged, the engine cannot rev as high as usual because it can’t eliminate the exhaust as quickly. The result is a car that won’t accelerate as smoothly or at all.
Issues With the Engine
As you might expect, an acceleration issue could occur because of a problem with the car’s engine. These engine problems are often the most severe issues you’ll encounter, making it essential to identify them early.
Low Engine Compression
One of the more serious problems on this list is an engine with low compression. Your engine’s cylinders hold a tight seal to contain the combustion reaction that occurs within them. When the compression rate is high, the energy from this reaction powers the vehicle. When the pressure is low, the car won’t have the same amount of power.
This situation means that the pressure is somehow escaping. It could be because there’s a hole in a piston, a bad piston ring, leaky valves, or even a blown head gasket, all of which require significant repairs.
You could notice that your check engine light is on in this situation, signaling that a trip to the mechanic is in your future if you can get your car started to get it there.
Bad Spark Plugs
Spark plugs are an essential piece of your internal combustion engine because they send a signal to the combustion chamber to light the fuel and air mixture.
When the spark plugs stop working, the vehicle won’t accelerate adequately because the combustion won’t occur at optimal levels.
Bad Air Filter
Since your engine needs oxygen for the combustion process to begin, clean air filters are a must. These filters remove dust and other particles from the air to keep the combustion chamber free of debris.
Over time, the air filter will collect dirt and eventually clog. The good news is that changing an air filter is quick and easy, so consider yourself lucky if it’s the root cause of your acceleration problems.
Timing Belt Problem
Your timing belt handles a lot of performance-related jobs, including opening and closing your engine valves at the correct intervals. When this belt is worn or does not have the proper tension, it can’t do its job correctly.
The result is poor engine performance because the intake valve can’t let air into the chamber to create combustion, and the exhaust valve can’t release the toxic gas from the engine as efficiently. One result of this issue is acceleration problems.
Turbocharger and Supercharger Issues (Forced Induction)
Is your car equipped with a turbocharger? A malfunctioning turbocharger can make it feel like you’re pulling a trailer or other heavy item behind your vehicle by severely limiting your acceleration.
A turbocharger works by forcing air into the engine at higher revolutions, increasing combustion. However, a loose connection or hole in the turbocharger reduces airflow and creates acceleration problems.
Furthermore, if your vehicle is equipped with a belt-driven supercharger, similar problems can occur. Superchargers force air into the engine through a pulley system. If this system becomes damaged, your vehicle will struggle to accelerate.
Possible Electrical Problems
Since the early 1980s, vehicles have been equipped with a series of electronic sensors that monitor the combustion process. An electric device also begins the combustion process. When one of these components malfunctions, your car’s engine could experience performance issues.
Camshaft Position Sensor Malfunction
Modern vehicles have an electronic control module (ECM), a computer that relays information to various car components. The camshaft position sensor is responsible for sending camshaft speed data to the ECM, which it then uses to optimize fuel injection and ignition timing.
If this sensor malfunctions, it can’t send the right information to the ECM, and the engine might not receive the fuel it requires to accelerate.
MAF Sensor Issues
The Mass Airflow Sensor (MAF) measures the amount of air flowing into the engine and sends this data to the Powertrain Control Module. From there, this information helps the computer determine the engine’s current load.
If this sensor isn’t functioning, the engine’s airflow could be restricted, hindering the vehicle’s performance and causing acceleration problems.
Oxygen Sensor Malfunction
After fuel burns, the remaining gas exits the vehicle’s engine through the exhaust system. An oxygen sensor in this system measures the gases leaving the car and sends this data to the ECM. From there, the ECM determines if the vehicle has the right air-to-fuel ratio.
When this device malfunctions, the ECM doesn’t receive accurate information on the air-to-fuel ratio, so the car won’t perform at an optimal level. Poor acceleration is just one symptom of a bad oxygen sensor, as you might notice more potent emissions coming from your car, too.
Ignition Coil Problems
A vehicle’s ignition coil attaches to the battery and provides the current that allows the spark plug to light the fuel in the combustion chamber. When these coils aren’t working correctly, you could notice hesitations, poor idling, and acceleration problems.
Eventually, your car won’t start at all if you don’t address your ignition coil issues.
How to Fix a Car That Loses Power When Accelerating
Now that you’re aware of what could be causing your car to lose power when accelerating, it’s time to develop a solution.
There isn’t a catch-all repair when a car loses power when accelerating because there are many underlying issues that can cause this to occur. However, it’s advisable to start with the least expensive fixes so you don’t end up rebuilding your engine when the issue was a clogged fuel filter.
Change the Filters
Replacing the vehicle’s filters is the easiest potential fix to an acceleration problem. Technicians will usually replace, or at least offer to replace, your fuel and air filters whenever you go for an oil change.
It isn’t necessary to change them every time, but you should plan to change your air filter every 12,000 to 15,000 miles and your fuel filter every two years or 30,000 miles.
Replace Essential Components
Many issues on this list require the replacement of the broken component.
For example, if you have a bad fuel pump, timing belt, ignition coil, or sensor, you’ll need to have the part replaced. Most of these parts are tricky to install on your own, so it’s best to visit a mechanic if you don’t have experience with them.
Clean or Repair the Problem
Other issues, like a clogged exhaust or fuel injectors, might not require a full replacement because it’s possible that your technician can remove the obstruction or clean the system, and you can get a few more years out of them.
You can also put fuel additives into your gas tank to clean your exhaust or fuel injectors. These additives might not work on more severe clogs but are a cost-efficient way to improve your acceleration issues without visiting a mechanic.
It’s possible to clean your spark plugs, too, but be aware that you’ll have to pull them out and manually wipe them down. At this point, it might be a good idea to replace them, especially if it has been a while. Ideally, you’ll want to replace your spark plugs every 20,000 to 30,000 miles.
Low Engine Compression Fixes
The most severe issue on this list is an engine with low compression because it means that pressure is somehow escaping from it.
If you have a hole in your piston, you’ll have to take the entire engine apart to identify the issue. This repair job is expensive, so you might find yourself shopping for a new car shortly.
For a leaky valve, you can use an oil stop-leak product for a temporary fix. However, you might have to replace the seal, which is a significant job.
A blown head gasket can cause many problems for your car, including overheating, coolant leaks, and discolored oil. This repair is pricey, but you’ll need to complete it before using your vehicle again.
Final Thoughts
In some cases, a car losing power when accelerating is a symptom of a relatively minor issue that you can repair within minutes. Other times, it signals a catastrophic problem that could force you to buy a new vehicle.
For the most part, you can look at the symptoms to determine the severity, as leaks and other indications generally accompany serious engine problems. When your car isn’t accelerating, start with the most straightforward fixes and when all else fails, go to a mechanic to have the issue diagnosed.
