I can’t accelerate or go fast while driving

When I fully step on the accelerator the vehicle will be moving at a speed of 40kmh and I can't even over take other vehicles

My car has 15000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there. The lack of acceleration you feel suggests several possibilities. There could be low fuel pressure caused by a faulty fuel pump or a faulty fuel pressure regulator. It could be a lack of incoming air to the engine caused by a very dirty air filter or a faulty MAF (mass airflow) sensor, incorrectly calculating the incoming air to the engine.

A restricted exhaust system caused by a plugged catalytic converter is also another possibility. There are more possibilities: a faulty TPS (throttle position sensor), engine or ignition timing problems, etc. I recommend having your vehicle’s [lack of power during acceleration](https://www.yourmechanic.com/services/car-is-not-getting-enough-power-inspection diagnosed and repaired by a certified technician, such as one from YourMechanic.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Airflow sensor: When your airflow sensor is failing or dirty, it can send wrong signals to your engine`s computer that can result in power losses while accelerating.
An engine that is hesitating to accelerate is most likely dealing with a fuel/air mixture that is too lean. Engine`s that are running inefficiently will begin to show signs like hesitation which will only become worse over time.
The most typical causes of a car not accelerating while driving include a faulty sensor, contaminated fuel or air filters, or a faulty timing belt. Generally, this isn`t something you should ignore.
One of the most common reasons for poor acceleration is a problem with your car`s air intake system. If there is something blocking the air flow into your engine, it will prevent your car from getting the oxygen it needs to create the combustion needed for acceleration.
You will feel a loss in power while accelerating and at times intermittent jerks. To solve this issue find the fuel filter located in the engine bay or near the fuel tank in your car`s trunk. If the fuel filter is clogged replace it if you have the skills to do so or get it changed at your local mechanic shop.
This hesitation while accelerating can be the result of a number of issues, including something like a clogged fuel filter or even a broken fuel pump. Sometimes, something could also be wrong with the transmission.
If your engine revs up as you press down on the gas but your vehicle doesn`t accelerate as much as you`d expect, you may be dealing with transmission slipping. If you`ve ever tried to accelerate on ice, where your engine revs but your vehicle goes nowhere, you know the feeling.
Here are some possible reasons your RPM is going up and down while driving: Worn-out spark plugs. Vacuum leaks. Bad idle air control valve.
Common causes of why a car feels sluggish when accelerating include dirty mass air flow sensor (MAF), faulty spark plugs, defective throttle position sensor, clogged catalytic converter, faulty oxygen sensor, clogged air filter, and fuel system malfunctioning.
If a spark plug or multiple spark plugs are faulty, they will have trouble creating the spark that causes the ignition process in your vehicle. This results in your vehicle having trouble starting, hesitating or having issues with accelerating properly.
However, the three most common causes are natural causes, human error, and overload. Basically, any interruption between power generation and the supply of electricity to homes can cause a power outage. It can stem from inclement weather conditions, human error, equipment failure, and even animal interference.
A clogged fuel or air filter can make your engine sputter and your acceleration lag because the engine is not getting enough fuel or air, respectively. The combustion chamber needs the correct amount of air and fuel in order to generate combustion efficiently.
A clogged fuel or air filter can make your engine sputter and your acceleration lag because the engine is not getting enough fuel or air, respectively. The combustion chamber needs the correct amount of air and fuel in order to generate combustion efficiently.
Fuel System Issues: One of the most common reasons for a car to bog down when accelerating is an issue with the fuel system. If your car isn`t getting enough fuel, it will bog down when you try to accelerate. Or if your fuel tank has bad fuel or your fuel system is clogged, you may experience a bogging down.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

When start out driving when accelerate does good to 2000 rpm and then when go to accelerate more it drops off and have to let off
ANSWER : Hello. From what you describe, it would appear that your vehicle is experiencing some sort of engine performance issues. Problems accelerating under load can be caused by many things. A few common causes are issues with the ignition, engine management, or fuel systems. If any components to those systems, such as an ignition coil, module, sensor, or fuel pump, have an issue, they can cause the engine to experience problems under load. If the Check Engine Light is on, I would recommend having the trouble codes scanned to see if that may shed some light on the issue. If the check engine light is not on, then the first thing I would do is test the vehicle’s fuel pressure, as fuel pressure issues can sometimes occur without the light coming on. A certified professional from YourMechanic can inspect the acceleration issue for you in person to pinpoint the appropriate repair.

I bought a used car 2010 nissan versa and when I go uphill it slows down alot. When going uphill it says go 60mph I am at that sp
ANSWER : Hi there. When a car is slow to accelerate it can be caused by multiple issues, ranging from fuel systems that are clogged or damaged to an ignition system component failure. It is also possible that something in the driveline system is dragging which causes the lack of acceleration. Since there are so many different possible issues, the best way to start the diagnosis process is to have a professional mobile mechanic from our team come to your location and complete a car is slow to accelerate inspection.

When I turn on my car I hear a knocking noice on it and when I accelerate it’s worse.and won’t go fast when I accelerate it don’t
ANSWER : If the noise is coming from the engine, then it sounds like you may have bad piston connecting rod bearing. This would account for the noise getting worse and very low power. If the noise never goes away it could also be internal to the transmission or clutch assembly, though if it was from the transmission, then it would go away when sitting stationary with the clutch depressed. Before any mystery noise can be determined, I would suggest have a qualified technician, such as one from YourMechanic, come and diagnose the noise in person. This way you can get a thorough diagnosis and know exactly what repairs are needed.

Can front wheel drive car engine power rear wheel drive
ANSWER : Anything is possible with enough engineering. The changes you are looking at would take major structural changes and would definitely not be an easy job. You could possibly consult a manufacturing engineer to get more details on how this could actually be carried out and whether it would be feasible.

My car want go drive but will go in reverse and shift in 1 or2 and drive some, so what could it be.
ANSWER : This is an internal transmission problem with the valve body or the 1-2 sprag unit binding internally in the transmission. Have a qualified transmission diagnose the problem firsthand to pinpoint what is going on. The mechanic may have to do a pressure test to isolate the cause of the shift concern.

Car will not accelerate quicking in drive; have to to put into 1st and go trough gears to make it go?
ANSWER : It sounds like you are having transmission problems, maybe some slipping going on or the unit is malfunctioning due to a low fluid level. Find the owners manual for the proper procedure to checking the transmission fluid level. Some vehicles must be running while performing the check. If the fluid is low, top it off with some compatible with your make and find the leak.

If the fluid is level is correct, but is dark and smells burnt, service may be required. Consider YourMechanic, as a certified technician can diagnose your acceleration issue firsthand. The mechanic will be able to inspect the linkage between the shifter handle and transmission assembly for any alignment problems.

Shifting from 2nd to 3rd, car stopped going fast. Now it won’t go at all.
ANSWER : It is possible that your clutch has failed. The sound you are hearing is likely due to the clutch not engaging with the engine due to it being worn. I would recommened having your transmission inspected by a qualified transmission expert to determine if your clutch requires replacement in order to resolve this issue. This inspection may require removal and partial disassembly of the transmission in order to verify that the clutch has failed.

My car won’t accelerate in drive. But will accelerate in park or reverse. The last couple of days. While driving the battery ligh
ANSWER : You may have a defective transmission valve body or the transaxle is bad internally. The manufacturer recommends replacing the valve body assembly first and then the complete transaxle if the problem is still happening.

I suggest having you transmission tested by a experienced transmission mechanic first and then move forward with the recommended repairs after being tested.

If you’d like a second opinion on this, contact a certified mechanic who can assess your acceleration issue firsthand and confirm my suspicions.