12 Reasons Your Car Won’t Accelerate (And How to Fix It)
In this article, we’ll explore the most common causes of this problem, help you understand what’s going on under the hood, and get your car back on the road.
Why Your Car Won’t Accelerate When You Step on the Accelerator
Acceleration problems are common in vehicles with high mileage. But they usually don’t signal any serious or immediate concern for a major engine problem. As with any car problem, you should check for possible minor causes first in order to identify and possibly solve the problem.
Here are some of the most common reasons for lack of acceleration: There are many different reasons for this. Therefore, if you are not sure how to fix a car that won’t accelerate, it is recommended that you take your car to a trusted mechanic to have the problem properly diagnosed.
1) Clogged or faulty air mass sensor
The air mass flow sensor (or meter) is located and attached to the air filter. Since the function of the air mass sensor is to measure the mass of air flowing into the intake, a clogged or defective air mass sensor can send incorrect data to the engine ECU to calculate the air-fuel mixture. A very common symptom of a faulty air mass sensor is that the car will not speed up.
2) Faulty oxygen sensor
An oxygen sensor (also known as an O2 sensor) is a device whose function is to monitor the exhaust gases of a vehicle so that it can analyze the air-fuel ratio flowing through the vehicle’s engine. Simply put, you need the right amount of fuel to burn properly in the combustion cylinders so that your car can run smoothly and accelerate when needed.
This sensor sends information about the amount of fuel consumed to the engine’s computer unit. If this sensor is damaged, your vehicle’s engine won’t know what mixture ratio it should use and may end up with a fuel-rich mixture. This can cause your vehicle to accelerate slowly, even when you press the accelerator pedal all the way, and be unreliable when you need it.
How to fix the problem: Use an automotive diagnostic tool to identify which sensor is bad. Replace the O2 sensor.
3) TPS failure
The basic principle of the throttle position sensor (TPS) is to detect the opening of the throttle valve, which is controlled by the accelerator pedal. The TPS then sends this data to the ECU. If the TPS fails, the accelerator pedal will no longer be able to control the engine speed, and the engine speed will increase or decrease even when the pedal is not being pressed.
How to solve the problem: Replace the throttle position sensor.
4) Dirty or clogged fuel filter
A dirty or clogged fuel filter is also one of the reasons why your car doesn’t accelerate as well as you would like when you need it to. If your fuel filter is dirty, your engine won’t get enough fuel to give you the acceleration you need. Replace your fuel filter as soon as possible.
How to fix the problem: Replace your fuel filter.
5) Clogged or dirty air filter
Just like the fuel filter provides your engine with clean fuel, the air filter provides your vehicle’s engine with clean air for the air-fuel mixture that is sent to the combustion chamber for combustion. If your air filter is clogged, your engine won’t get the proper air-fuel mixture, which will cause sluggish acceleration. Replace your air filter as soon as possible.
How to fix the problem: Replace your air filter. If you have a reusable air filter, such as a K&N, follow the cleaning instructions.
6) Faulty fuel injectors
Fuel injectors are responsible for delivering fuel to your engine. If they don’t work properly, your car probably won’t be able to accelerate properly. If your fuel injectors are dirty, clogged, damaged, or failing, they can restrict the flow of fuel to your engine, causing poor acceleration and deceleration, or even a stall.
How to fix the problem: Use a diagnostic scan tool to read error codes from your car’s computer. If the error code indicates a fuel injector problem, try cleaning it with a fuel injector cleaner. If cleaning doesn’t help, replace the fuel injector.
7) Emergency Mode
Limp mode is a safety feature designed to protect your engine from damage. If your car’s computer detects an engine problem, your car may go into limp mode, limiting engine power and speed. This will definitely cause your car to have trouble accelerating and may cause the check engine light to flash.
How to fix the problem: Use an OBD2 scanner to scan your car’s computer for trouble codes to pinpoint exactly what is causing your vehicle to go into limp mode.
8) Faulty fuel pump
The fuel pump is responsible for delivering fuel from the gas tank to the engine. If it doesn’t work properly, it can cause a lack of fuel pressure, which can lead to poor acceleration. When the fuel pump goes bad, symptoms include sputtering or stalling while driving, difficulty starting the engine, and reduced fuel economy. How to fix the problem: Replace the fuel pump.
9) Timing Belt
This component promises it. The timing belt is like the VIP in the list of engine components. If this belt is out of alignment even by one tooth, you can have serious problems with acceleration.
How to fix the problem: Replace the timing belt.
10) Slipping Clutch
If you have a manual transmission, a slipping clutch can cause acceleration problems. This happens when the clutch disc fails to engage properly with the flywheel, causing what feels like your car has lost power while driving. It’s similar to a person trying to run on ice. Signs of a slipping clutch include a burning smell, difficulty shifting gears, and poor acceleration.
How to Fix: Replace the clutch.
11) ECU
The ECU, or engine control unit, is responsible for regulating the performance of your car’s engine. If it’s malfunctioning in some way, it could be causing your car to have trouble accelerating. A faulty ECU can cause a variety of other issues, including misfires and poor fuel economy.
How to Fix: Repair or replace the ECU.
12) Clogged Exhaust
Two major components of your car’s exhaust system are your catalytic converter and muffler. If either one of these becomes clogged or damaged, this can restrict exhaust flow and lead to a reduction in engine power and acceleration. This is especially the case with turbocharged vehicles which require proper exhaust flow to work as intended.
How to Fix: Check all components of the exhaust system to look for clogged or damaged parts. Replace if necessary.
Checking for Trouble Codes
If your car won’t accelerate, one of the first things you should look for is the Check Engine light. This light will come on if there is a problem with your car’s engine or emissions system. It’s worth mentioning that the Check Engine light does not always mean that there’s a major problem.
To check for trouble codes, you will need an OBD2 scanner. This is a device that plugs into your car’s OBD2 port and reads the codes stored in your car’s computer. Once you’ve connected the scanner, you can retrieve the trouble codes and get a better idea of what is causing your car to not accelerate properly.
Once you see what trouble codes have been stored, you can use them for diagnosis. These codes will give you a better idea of what is causing your car to not accelerate properly.
But the fact is that trouble codes don’t always pinpoint the exact problem. In some cases, the codes may be related to a minor issue that can be easily fixed. In other cases, the codes may indicate a major problem that requires immediate attention.
If you’re unsure what the codes mean, have a mechanic diagnose further – don’t rely on the codes alone.
Acceleration Problems’ Impact on Fuel Economy
When your car won’t accelerate properly, it can have a significant impact on your fuel economy. Poor fuel economy is a common symptom of a car that won’t accelerate as it should.
You may think that if your car is accelerating poorly, it’s using less gas so your fuel economy should be better. But the opposite can actually happen! If your car is struggling to accelerate, it means that your engine is working harder than it should, which can lead to increased fuel consumption.