Car Not Accelerating but RPMs Up? Identify and Fix the Problem

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Diagnose why your car won’t move when you press the gas
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RPM stands for revolutions per minute, and the number of RPMs on your tachometer indicate how many rotations your engine’s crankshaft is making every minute. The more rotations, the faster you should go. But if your car doesn’t feel like it’s accelerating at the rate it should be based on how hard you’re hitting the gas pedal, it points to two systems: intake going into the engine, or the power the driveshaft is receiving from the transmission. In other words, something is wrong with the air and fuel feeding into your engine, or something is wrong with your transmission’s power output. In this article, we’ll break down every potential option, how the repair will work, and how much it’ll cost.

1

Low Transmission Fluid

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  1. The transmission is responsible for shifting your vehicle’s gears and transferring power from the engine to the wheels. Inside, transmission fluid pumps through the components to keep the gears lubricated and help with heat dissipation. If the fluid is low, the transmission will struggle to transfer the power you’re sending to the engine to the wheels. [1]
    • Other symptoms: Your gears slip, shifting gears becomes difficult, and grinding noises come from your vehicle.
    • The fix: Check your transmission fluid by removing the dipstick when the engine is cold. If it’s low, add more fluid to resolve the problem. See a mechanic if the problem reoccurs soon.
    • The cost: If you only need more fluid, expect to pay $20 or so. If there’s a leak or you need a transmission fluid change , it’ll cost $50-200.
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2

Bad Torque Converter

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  1. The torque converter is a fluid coupling between your engine and the transmission. To put it simply, the torque converter allows the engine to continue running when you brake or idle. [2] If your torque converter is bad, your transmission won’t transfer power correctly. [3]
    • Other symptoms: Overheating, slipping gears, and trouble shifting. You’ll also notice your transmission fluid going bad extremely quickly when you refill it, and unique engine shaking over 30–45 miles per hour (48–72 km/h).
    • The fix: A transmission specialist will look at your torque converter and assess the proper repair.
    • The cost: A new torque converter typically costs $500-1,000.
3

Disconnected Drivetrain

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  1. The drivetrain sits under the engine bay where the transmission connects to the axle and spans the length of the center of the car. It transfers power to the wheels and enables them to move. But if your drivetrain isn’t properly connected to the axle or there’s a loose connection between the drivetrain and the powertrain, your vehicle either won’t accelerate or struggle to get up to speed. [4]
    • Other symptoms: Big vibrations coming from underneath the vehicle when it’s on, difficulty turning, and loud clunky noises.
    • The fix: See a mechanic to have them diagnose and repair your drivetrain. They’ll either reconnect it to the powertrain or replace it.
    • The cost: Reconnection should only cost $400-1,000. Unfortunately, replacements tend to be very expensive. Expect to spend $4,000-10,000 depending on how powerful your engine is and how big your vehicle happens to be.
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4

Bad MAF Sensor

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  1. The MAF (mass airflow) sensor is responsible for measuring the amount of air that flows into the engine. The amount of air is important because it’s a key component in the air + fuel + spark equation that helps each cylinder fire in the engine fire. If the MAF is sending bad information to your engine’s computer, you may not be getting enough air to burn the fuel you’re feeding into the engine. [5]
    • Other symptoms: Your check engine light pops on, your engine misfires, and you get poor gas mileage.
    • The fix: You probably need to clean your MAF sensor . If that doesn’t work, it may need to be replaced, so see a mechanic.
    • The cost: If your MAF sensor needs to be replaced, it’s likely to only cost $300 or less.
5

Throttle Position Sensor

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  1. The throttle position sensor monitors your throttle valve to ensure it’s opening as much as you’re telling it to open with your gas pedal. If that throttle sensor is bad, your valve won’t open to match the amount of spark and fuel your engine is receiving and you’ll end up wither terrible acceleration. [6]
    • Other symptoms: Your check engine light pops on, you get strange fuel surges, your engine surges, or your gas pedal doesn’t respond properly.
    • The fix: The sensor probably needs to be replaced, so see a mechanic to have the work performed.
    • The cost: Expect to spend around $150-250 getting your throttle position sensor replaced.
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6

Clogged Fuel Filter

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  1. The fuel filter cleans the fuel of impurities and sediment before it leaves your fuel line and enters the engine. Over time, that filter soaks up a ton of debris, which can cause the amount of fuel that actually enters your engine to be lower than it should be. This will lead to a high RPM and poor acceleration.
    • Other symptoms: Engine misfires, stalls, and loud noises coming from the fuel pump.
    • The fix: The odds are high you only to clean your fuel filter , so remove it, spray it with a solvent cleaner, and wait an hour before replacing it.
    • The cost: If the problem persists or your fuel filter needs to be replaced , you’ll likely only need to spend $50-175.
7

Bad Fuel Pump

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  1. Your fuel pump is located near your fuel tank. If the name didn’t give it away, its job is to pump fuel from the tank to the engine. If it isn’t pumping enough fuel though, your engine will struggle to maintain speed when you accelerate. [7]
    • Other symptoms: Your car stutters, you hear a whining noise coming from your fuel pump, and your vehicle just generally runs inconsistently.
    • The fix: See a mechanic to have the fuel pump replaced. This isn’t a particularly complex replacement, but it does need to be performed by a professional.
    • The cost: The expensive part here is the actual fuel pump, not the labor. It’ll likely run $900-1,100.
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8

Bad Throttle Body

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  1. The throttle body is responsible for controlling the amount of air as it flows inside your engine. Without the proper amount of air moving into each cylinder, the spark and fuel won’t combust properly. The RPMs will move up, but you won’t see that power reflected in your actual acceleration. [8]
    • Other symptoms: Your engine idles too fast or too slow or you get surges in your electrical system which cause dash lights to get bright or dim. Your check engine light will also likely turn on.
    • The fix: The throttle body usually just needs to be cleaned. If you know how to do minor engine repairs, spray throttle-body cleaner between the air cleaner and intake manifold.
    • The cost: If you pay a professional to clean the throttle body for you, it’ll cost $100-300.
9

Worn Clutch Disc (Manual Transmission Only)

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  1. If you drive a manual car, you have a manual transmission that you control with your gear changer and clutch. Inside the transmission, there is a disc that spins to shift the gear. As an additional part of its job, that disc absorbs the friction from the spinning gears. If this disc wears down, it can cause your vehicle to lose the power it should have when you change gears. [9]
    • Other symptoms: Weak acceleration, noises, strange burning smells, and a loose or sticky clutch pedal.
    • The fix: The disc almost certainly needs to be replaced. See a transmission specialist to have them resolve the problem.
    • The cost: It really depends on your make and model. On the lower end, expect to spend $1,200-1,400. If you need the transmission to be rebuilt, it can cost up to $3,000.
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      Tips

      • If your vehicle is running alright at low speeds and you’re going to the mechanic immediately, don’t worry about pulling over to call a tow truck. You can make it to the repair shop so long as you go slowly.
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      Warnings

      • Do not begin tinkering with your engine or transmission if you don’t have any formal training. These components are essential for the health and functionality of your vehicle, and if you make any minor mistakes you could end up causing expensive damage. [10]
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      Thanks for reading our article! If you’d like to learn more about car maintenance, check out our in-depth interview with Duston Maynes .

      References

      1. ↑ https://www.thedrive.com/maintenance-repair/37310/low-transmission-fluid
      2. ↑ https://www.mytransmissionexperts.com/failing-torque-converter/
      3. ↑ https://atlanticmotorcar.com/casestudies/bmw-audi-and-volvo-torque-converter-problems/
      4. ↑ https://vehicle.firestonecompleteautocare.com/cadillac/xt5/2022/repair/drivetrain/
      5. ↑ https://www.samarins.com/glossary/airflow_sensor.html
      6. ↑ https://www.cars.com/auto-repair/glossary/throttle-position-sensor/
      7. ↑ https://www.motortrend.com/how-to/bad-fuel-pump-symptoms/
      8. ↑ https://haynes.com/en-us/tips-tutorials/what-is-car-throttle-body-and-what-does-it-do
      9. ↑ https://www.eaton.com/content/dam/eaton/products/clutches-brakes/commercial-vehicle/eaton-heavy-duty-clutch-service-manual-installation-instructions-en.pdf
      1. ↑ https://www.consumerreports.org/car-repair-maintenance/cars-most-likely-to-need-new-transmission-what-to-buy-instead/

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