7 Reasons Why Your Car is Slow to Accelerate

Have you ever been in the situation where you step on the gas pedal to accelerate but you don’t pick up any speed? A slow acceleration problem is generally found in vehicles which have a lot of miles on them.

This can be a dangerous situation if you’re entering a busy state road or interstate which requires you to accelerate quickly. The problem can also occur if you’re trying to drive uphill but you’re unable to accelerate fast to get up the hill.

In these cases, it will become clear that your engine simply doesn’t have the power or the support to provide the acceleration demands that you’re placing on it.

Top 7 Causes of Your Car Not Accelerating Properly

When you can’t pick up speed fast enough, it doesn’t necessarily mean that your engine is bad. It just means there is some component of your vehicle which is malfunctioning and not allowing your engine to handle these faster acceleration demands. Here’s are some possible culprits:

1) Oxygen Sensor Problem

The function of the oxygen sensor is to keep track of the car’s exhaust emissions and determine the amount of fuel that is needed in the internal combustion chamber by tracking the air to fuel ratio.

If the oxygen sensor were to malfunction, the wrong amount of fuel would get burned during the combustion process. This would create a rich fuel mixture, which would result in slow acceleration as you step on the gas pedal.

2) Air Flow Meter Problem

The air intake cleaner has an air flow meter attached to it. As air flows into the air intake cleaner, the air flow meter calculates the mass of the air and then relays this information to the engine control unit.

Once the ECU has this information, it knows how to calculate the proper mixture of air and fuel. If there is a problem with the air flow meter, then it will give the wrong information to the engine control unit. This will result in slow acceleration.

3) Bad Timing Belt

The timing belt needs to be in excellent condition. If there is just one tooth on the belt that is worn out, then you may have acceleration problems as you’re driving.

If you don’t replace the timing belt soon, then you could have entire teeth on the belt break off and go missing. Then you’ll start to see the car really slow down and not pick up speed, and eventually you’ll have expensive engine damage if the belt breaks.

4) Dirty Fuel Filter

If your fuel filter is clogged up with dirt and debris, then it is not going to let fuel pass through it. That means the fuel can’t enter the engine, which means you won’t be able to accelerate properly when you step on the gas pedal. In this situation, you must simply replace your fuel filter.

5) Electronic Error

If the central computer (ECU) or electronic system that controls your vehicle is getting glitches or errors, then it could wrongly determine that excessive amounts of fumes are being generated by your vehicle. Because of this, the computer will limit your ability to accelerate.

6) Bad Throttle Position Sensor

The throttle position sensor is what analyzes the opening angle of the throttle valve. Once it detects this information, the throttle position sensor sends it to the engine control unit.

If this sensor were to malfunction, the gas pedal would no longer be able to control the speed of the engine because the pedal controls the throttle valve.

7) Neutral Gear

There are some drivers who can’t pick up speed in their cars because they accidentally change the gear to Neutral instead of Drive. Either that or they’ll accidentally change it to Neutral as they’re already driving.

Sometimes if the shift stick is easy to move, this can happen. If you drive with the car in Neutral, then your car will simply rev its engine and not accelerate at all.

15 thoughts on “7 Reasons Why Your Car is Slow to Accelerate”

  1. How do i know which one is my problem? When i go up a hill the car doesn’t pick up speed like i can’t get it above 60 mph and i press on the accelerator and the revs just keep going up quickly but the speed doesn’t go up. Wha could be the problem ?

    • This sounds like a slipping clutch or torque converter. This will likely be most noticeable in 3rd or 4th gear. If you have a manual transmission, a clutch replacement should fix the issue. For an automatic, further diagnosis is needed by a mechanic in your area.

  2. My 3s start perfectly, and engine light goes off but takes longer to accelerate, diagnosis shows the car is OK but you have to press the pedel down to the end opening the throttle valve wide to Start picking up, and Some times the engine light blinks and gain power at the same time, any idea for this

    • A blinking check engine light often means the car is misfiring. I would do some troubleshooting to see why this is. Check the spark plugs and wires, replace if necessary. Look for other check engine lights that are stored in the computer. These will help you understand what’s causing the misfires.

  3. Hi, my car not picking up acceleration when I stop and going again once it pick up then no problem is going ok, I did service last week my car is diesel Bmw 2008 5 series and coming smoke also when i accelerator it I don’t know what to do now, car just slow down in 1 or 2 gear.

  4. When I go to motorway my car had no problem but when I go to small gear some time not pick up like engine has no power.
    I did service last two we Ago all filter and oil changed don’t know what to do .
    Mechanic check with computer he said everything is ok just take your car on motorway to burn the diesel, I went through but still not very good.

  5. Hi. I have a fiat Punto Evo 2012. When go up the hill my speed drop to 40km/h in 3rd gear. The speed doesn’t increase and the acceleration pedal is completely down. I need some advice please

    • 40 kph is pretty slow to go up a hill in 3rd gear, especially with a smaller displacement motor. I used to have a Subaru WRX with nearly 300 hp, and even that car would struggle a bit under those conditions. Try dropping down to 2nd gear to see if it helps.

      If you think it’s more than just the gear ratios working against you, I’d ask some fellow owners on a forum to see if they have any advice.

  6. I changed my fuel pump but my car stops running on slow motion. But when I start the engine back,it will start accepting again. It has happened several times. What could be responsible for that and what is the remedy? Thanks

  7. Hello. I have an 01 nissan
    Pathfinder. It has a very hars time getting up to speed and sometimes it backfires while speeding up. Also it accelerates all on its own when I’m going slow. It also has a hard time going up big hills. I have to speed in order to ger past a hill. Someone said it could be my spark plugs but after reading this it may be something else. Any ideas?

    • It could be a vacuum leak, could be spark plugs, but it’s anyone’s guess unless you take it to a shop to have them diagnose the problem.

  8. Looking for advice on a 2006 Mistubishi Galant 2.4l with an automatic transmission. It really struggles to pick up any speed. The rpm gauge is in sync with the speedometer and doesn’t jump up. It seems to be a little better if I start with L1, the L2, L3, then D. But only a little better. When I let it shift on its own it seems to be a smooth shift when it eventually builds up enough rpms. Catalytic converter was changed around 4 years ago. The problem started around a month ago and have gotten progressively worse. Any suggestions? Thanks!


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