There are multiple working elements in your car’s operation to get your vehicle to move forward. The engine’s throttle is the very first step in car movement. The throttle pedal in your car connects directly to the engine and air throttle body for fuel injection.
A spark ignites, causing the engine piston to drop down and turn the crankshaft. The more you put your throttle pedal towards the floor, the more air can take in affect crankshaft rotation speed. This is the action of acceleration in your car while driving.
However, if you are driving your car and losing power to speed, you pretty much only have two scenarios. You don’t have enough petrol, or you don’t have enough power in your car.
There are many reasons why your car loses its power, or is prevented from accelerating significantly, the harder you press on the throttle pedal.
The most common reasons why a car doesn’t accelerate when driving are: a faulty sensor, dirty fuel or air filters, or a bad timing belt. Usually, this is not something you want to ignore.
Reasons Your Car Won’t Accelerate When You Push the Gas
Now, here’s some bad news: There isn’t a straightforward answer to why your car doesn’t accelerate like it should.
To determine the problem’s cause, you (or a mechanic) will have to go through some testing to find the cause of the problem. Refer to a repair manual or repair database to find out the correct testing procedure for your application.
Typically, you’ll find one or more of the following problems to be the cause of poor acceleration:
#1. Dirty Oxygen Sensor.
Every vehicle is equipped with an oxygen sensor that works with a mass air flow sensor. The air flow filter can get clogged with dirt and debris, which affects vehicle performance.
The dirty sensor could affect your vehicle’s ability to accelerate, and you may notice a decrease in fuel efficiency, too. If your problem is with the oxygen sensor, the mass air flow sensor, or both, you may have to take it to a mechanic
When the oxygen sensor is dirty, it will likely have to be replaced. If your mass air flow sensor is dirty, however, it can likely just be cleaned. Having a dirty sensor may cause the “Check Engine” light to illuminate on the dashboard.
How to fix: Use an automotive scanner to determine which sensor is faulty. Replace the O2 sensor.
#2. The Throttle Position Sensor is malfunctioning.
A Throttle Position Sensor, or “TPS” for short, can also be the culprit for poor acceleration. The Throttle Position Sensor tells the engine computer how much to adjust based on the opening of the throttle valve in the engine.
A throttle position sensor can get dirty or fail, which means it won’t determine the throttle position accurately. The sensor will give the engine false data, which creates poor performance and leads to slower acceleration in the car.
How to fix it: Replace the throttle position sensor.
#3. Clogged Fuel Filter.
Every car has a filter in the engine, which is called a fuel filter. The fuel filter’s job is to clean and purify the fuel that is entering the vehicle, as well as allow enough fuel into the engine.
If the fuel filter gets clogged with contaminants, it will not provide the engine with clean enough fuel to run properly.
Additionally, a lot of the pollutants that get into the car’s system will end up in the fuel tank and can break apart, which ultimately affects the car’s performance. Replacing the fuel filter with a new one should clear up the problem.
How to fix it: Replace the fuel filter.
#4. Dirty Air Filter.
The engine has another filter, and it is called an air filter. The air filter gives the engine the air that it needs to work properly.
The air filter could be dirty, which in turn restricts clean airflow to the engine.
How to fix it: Replace the air filter. If you have a reusable air filter (ie, K&N), refer to the directions on cleaning it.
#5. Mass Air Flow Sensor Clogged or Malfunctioned.
There is a mass air flow sensor (or meter) that is either located and attached to the inlet air cleaner; since the function of the air flow sensor is to measure air mass that flows into air intake, a clogged or bad mass air flow sensor could incorrectly provide data to the engine ECU for calculating the air fuel mix.
A very common symptom of an air flow meter malfunction is a car that struggles to get up to speed.
How to fix it: Clean or replace the MAF sensor.
#6. Bad Fuel Injector.
Fuel injectors were designed to provide fuel into the engine, while if they don’t work right, your car likely won’t be able to accelerate properly.
A dirty, clogged, damaged, or faulty fuel injector may affect the flow of fuel into the engine, which may result in poor acceleration, hesitation, or even stalling.
How to fix it: Use a diagnostic scan tool to read error codes from the car’s computer. If the code indicates a problem with the fuel injector, you can try cleaning the fuel injector with a fuel injector cleaner. If cleaning doesn’t work, replace the fuel injector.
#7. Limp Mode.
The limp mode feature is there for your protection. When the car’s computer detects an issue with your engine, it may cause the car to go into limp mode, which limits the engine’s power and speed.
Of course, this will result in issues with acceleration, usually also accompanied by a flashing check engine light.
How to Fix: Use an OBD2 scanner and scan the computer for fault codes to see what caused the vehicle to enter limp mode.
#8. Faulty Fuel Pump.
The fuel pump is responsible for the delivery of fuel from your gas tank to the engine. If there is an issue with that, it can cause a lack of fuel pressure, which will cause poor acceleration.
Signs of a bad fuel pump include sputtering or stalling when driving, difficulty starting the engine, and decreased fuel efficiency.
How to Fix: Replace the fuel pump.
#9. Timing Belt.
As it sounds, the timing belt is sort of the VIP of an engine component. If this belt is off even by one tooth, it can create some pretty serious acceleration problems.
How to Fix: Replace the timing belt.
#10. Slipping Clutch.
If you have a manual transmission, a slipping clutch can cause acceleration problems. This is because the clutch disc fails to engage properly with the flywheel, which can make your car feel like it has lost power while driving (like trying to run on ice).
If you have these signs of a slipping clutch: a burning smell, difficulty shifting gears, and poor acceleration.
How to Fix: Replace the clutch.
#11. ECU.
The ECU (engine control unit) regulates performance on the car’s engine. And, if the ECU is malfunctioning in any way, it can cause you trouble accelerating. A bad ECU can cause several other issues as well, including fuel economy issues and misfires.
How to Fix: Repair or replace the ECU.
#12. Clogged Exhaust.
Two of the main components of the car’s exhaust system are the catalytic converter and muffler. If either of these is clogged or damaged, exhaust flow can be restricted, which may reduce engine power and acceleration. This is especially true for turbocharged vehicles that require good exhaust flow to perform properly.
How to Fix: Check all the components of the exhaust system to see if there are any clogged or damaged parts. If there are, replace some parts if necessary.
Looking for Trouble Codes
When your car is not able to accelerate properly, one of the first things you should do is check for the Check Engine light. If the Check Engine light is illuminated, it may indicate that there is a problem with your car’s engine or emissions system.
Although it is worth mentioning that the Check Engine light does not always mean your car has a serious or expensive problem. In some cases, it could be something as simple as a loose gas cap.
In order to check for trouble codes, you will need an OBD2 scanner that you can connect to your car. An OBD2 scanner is a tool that will plug into your car’s OBD2 port and read the codes stored in your car’s engine control unit.
After you connect and learn how to use the scanner, you can retrieve the trouble codes and provide yourself with a better starting point for diagnosing why your car is not able to accelerate properly.
Once you know what trouble codes are stored, you can begin to use the trouble codes for your diagnosis. The trouble codes will provide you with a good starting point to help determine why your car is not able to accelerate properly.
However, the trouble codes do not always tell you the true story. Sometimes, the trouble code that is set may only be related to a small issue that you can easily fix. And sometimes, the trouble codes will identify a serious concern that requires your immediate attention.
If you do not understand what the codes mean, have a mechanic diagnose the problem – do not rely on the codes by themselves.
Acceleration Problems’ Impact on Fuel Economy
When your car is not able to accelerate properly, poor fuel economy is not only a noticeable symptom, but it can be one of the deciding factors that sets off the alarm bells indicating that your car is not operating properly.
If you are still thinking, “if my car is accelerating poorly, then it is probably using less gas and has a better fuel economy”, you are mistaken. The opposite can and does happen.