When you press the gas pedal in your car, you expect it to go. Have you ever encountered a time when you revved the engine, the RPMs shot up, but it didn’t move as it should? When that happened to me, it was because I didn’t have enough transmission fluid in it, but there are other reasons this could happen.
When a car won’t accelerate, but the RPMs go up, likely there’s a transmission issue. This could be anything from low, or dirty transmission fluid, a clutch issue, or a problem with the torque converter. There could also be an issue with the ECM sensor, a vacuum line clog, or a dirty throttle body.
If this problem is happening to you, don’t worry because we have the answers you have been searching for. Here we’ll go over several issues that may cause your RPMs to increase while not accelerating.
What Are RPMs, How Are They Measured and Why Are They Important?
RPMs are Revolutions Per Minute. On a vehicle, it measures how many times the crankshaft makes one full rotation. They tell how fast the car engine is running. A car that idles at 500 RPMs is making 500 complete revolutions per minute.
It’s important to know the RPMs because the more revolutions per minute, the more power, and possibly more speed the engine is creating. The vehicle’s RPMs will also dictate when an automatic transmission shifts gears, and when you should shift if you have a manual.
RPMs also affect fuel economy. The faster the RPMs, the more fuel is used. That’s why it’s more fuel efficient to drive at lower speeds in higher gears.
Reasons Your Car Can’t Accelerate, but RPMs Go Up
When the engine revs, but you don’t accelerate, there’s usually—but not always—an issue between the motor and transmission. When the engine runs, it transfers power to the transmission which in turn rotates the wheels.
Let’s go over the most common problems, but keep in mind there’s no particular order here, and we can’t cover every single issue that could cause this problem.
Transmission Issues (Automatic Transmission)
Often, when the engine runs fine, but you’re not able to accelerate or move at all, it’s a problem with transmission fluid. If there isn’t enough fluid or it’s worn out and old, it won’t build up enough pressure to turn the gears. The vehicle may even stall.
Check the fluid level and add more if it’s low. When you check it and see a very dark transmission fluid or you feel grit when you rub a drop between your fingers, you’ll need to have it replaced. When replacing transmission fluid, make sure you replace the filter and gaskets as well.
Other automatic transmission problems you may encounter could be a faulty shift solenoid or you have worn out gears.
To replace a shift solenoid you’re looking at between $250 to $700. And if you have stripped gears, you’ll have to have the transmission rebuilt, which can set you back a few thousand dollars.
Fuel System Problems
There are several parts in the fuel system that can prevent fuel from getting to the engine. This can cause the engine to stall, run erratically, or rev up and then lose power when you try to accelerate.
You could have a clogged fuel filter, a failing fuel pump, or even a leak in one of the fuel lines. Typically these will cause sputtering, or the engine could stall altogether and your engine wont start up.
If you are mechanically inclined and able to perform the replacement of these parts yourself, you can save a lot of money, as a fuel filter replacement can cost from $50 to over $200. A fuel pump replacement starts at around $200 and can cost over $1,000 depending on the vehicle and the cost of the part.
Malfunctioning Engine Control Module
The Engine Control Module (ECM) is the vehicle’s “brain.” It controls many functions of the motor, transmission, and other systems. While it’s rare for the ECM to fail, it can happen. When the wrong information is getting sent to the ECM it could prevent the transmission from engaging.
You’ll need the expertise and high-tech tools of a trained mechanic to test the ECM. Replacing the ECM can vary widely in cost depending on the make and model of the vehicle. While it may only cost around $300 to have one replaced on a certain model, others could cost up to $2,000.
Bad Throttle Body
The throttle body regulates the air that enters the engine. When it’s dirty or clogged, the engine can sputter or run erratically. You may also experience a large loss of power. You may see high RPMs, but you won’t get the acceleration you’re looking for.
The throttle body sits between the air intake and the engine. You can pay a mechanic or dealership to clean it for you, which will set you back approximately $200 to $300.
Other options include replacing it altogether, as the part usually costs less than $20, or cleaning it yourself. It’s not a complicated process on most cars and a bottle of cleaner is around $15.
Ignition System Problem
The ignition system sends an electric charge to the spark plugs which ignite the fuel and air mixture in the chamber. If any of these parts are not working properly, you could experience a multitude of problems.
Check your spark plugs for worn electrodes and points, they could be fouled or just old and need to be replaced. Look at plug wires to find cracks or corrosion on the contacts. Then again you may have to replace the ignition coil itself.
The plugs and wires are not difficult to replace and generally don’t run more than $100 for both spark plugs and plug wires. The ignition coil on the other hand should be replaced by a mechanic as it can still hold an electric charge.
Replacing an ignition coil may cost you between $200 to $300.
Both automatic and manual transmissions have clutches, and these parts often wear out and need to be replaced. The clutch disengages the transmission from the wheels and you’re able to change gears.
When a clutch wears out, you may get the rev of high RPMs, but not the acceleration you’re expecting. It may also be difficult to shift gears in a manual transmission vehicle. Another issue that can cause high RPMs but no acceleration is a hydraulic fluid leak.
This fluid is what causes the clutch to work and disengage the transmission. When the fluid is low or not able to build up pressure because of a leak, you’ll have trouble with the transmission and shifting gears.
Automatic transmissions have clutch discs or clutch plates. These too wear down over time and can cause transmission slippage, and hard shifts when it changes gears.
Clutch replacement can be a very labor-intensive repair. The parts aren’t too expensive, but it takes a lot of knowledge, special tools, and a lot of labor to replace them.
The cost to replace a clutch in either a manual or automatic transmission may cost between $500 to $2,000 depending on the car and what kind of transmission.
You Have a Leak in Your Intake Manifold
Another possibility that can cause your vehicle to behave abnormally is a leak in your intake manifold. The intake manifold delivers air to the engine where it combines with the fuel. A leak will cause too much air to enter the cylinder, and your car will run “lean.”
There won’t be enough gas in the mixture to provide the power you expect when you press the gas pedal. This can lead to high RPMs but a weak acceleration, or maybe even stalling of the engine.
There are gaskets that help seal out excess air and dirt that can go bad over the life of the vehicle. Heat from the motor, vibrations, or normal wear and tear can cause these gaskets to become brittle and crack.
The parts only cost around $20 to $40, but it’s not easy to get to the intake manifold. If you’re a good mechanic you may be able to save yourself some money by replacing them yourself. For those of us who don’t know how to go about this, we’ll end up writing a check for between $300 to $600 if your intake is leaking.
You Have a Vacuum Leak
A leak in your intake manifold can also lead to a vacuum leak, which can cause very similar issues. Other sources of vacuum leaks include cracked or loose hoses or broken sensors.
These problems are usually easy to fix but can be very difficult to track down. On newer model cars, there are many more sensors and vacuum hoses running throughout the engine than on older model cars. Finding the problem can take a lot of time if it’s a very small leak or a hidden sensor that is difficult to locate.
Often a diagnosis tool may help you track down the leak or faulty sensor. If it’s a cracked hose, all you have to do is replace it with a new one. The same goes for a bad sensor, and these parts typically cost between $20 to $100 depending on the part, and the vehicle it’s going on.
Labor to replace these parts may cost around $100 to $200. If you know for sure that your vehicle has a bad sensor or cracked vacuum hose, you can save yourself some money by doing it yourself.
Torque Converter Problems
The torque converter is another part located in automatic transmissions. When these parts go bad you’ll notice signs such as shuddering, slipping, vibrating, or lag when shifting gears. These work to disengage the transmission so that it can shift into a higher or lower gear while driving.
If the torque converter has failed completely, you may end up experiencing high RPMs when you press the gas pedal, but you won’t go anywhere.
This repair can be difficult if you don’t have experience working on cars. A mechanic will charge between $500 to $2500 to replace one for you, depending on the type of vehicle.
Why Do Some Cars Have Higher RPM Than Others?
There are many factors that will determine the RPMs on a vehicle. The size of the engine, the gear ratio, and the weight of the vehicle can determine the number of RPMs. Race cars and performance cars will have much higher RPMs than typical street cars.
Diesel fuel engines tend to turn slower than gas powered cars, so they usually have lower RPMs than gas cars. The number of RPMs may also be factored in when you have a heavy-duty truck made for towing. Higher RPMs are good for more power, but are there any other benefits to having higher RPMs?
Are There Any Benefits to a High RPM?
As we already said, higher RPMs allow for more power. When towing a trailer, having higher RPMs allows for better speed when towing, and being able to tow bigger loads. In trucks, more power because of higher RPMs lets you haul more in the bed without slowing you down.
Higher RPMs also allow for more speed. Sports cars usually have a higher range of RPMs so they can reach faster top speeds. The increase in revolutions per minute allows for easier passing on the highway, as well as being able to merge into swift traffic easier.
Another benefit of having more RPMs is being able to climb hills easier. If you live in a mountainous region, or have a lot of streets with steep hills, having more RPMs can make it easier to get up these steep inclines.
Disadvantages of High RPM?
Although having a vehicle with a higher range of RPMs can be beneficial, there are also some disadvantages. The faster a motor revs, the harder it works. A harder-working, faster revving motor means more heat generation.
Vehicles already generate a lot of heat when they are running, but when they run even faster, they create a lot more heat which can cause overheating. You’ll have to keep an eye on that temperature gauge when you’re hitting high RPMs.
Another disadvantage is decreased fuel economy. A faster turning engine uses more fuel. If you’re using those high revolutions while towing a heavy load, you’re using even more fuel.
Lastly, vehicles that hit higher RPMs consistently have more wear and tear on their engines. The faster speeds add a lot more stress and friction to the engine components. Cylinders, pistons, piston rings, bearings, camshafts, valves, and more all spin much faster and are subject to more stress.
This stress, the excess heat, and more friction can lead to more repairs in the long run. Are there certain tips to help your car last longer, even if it has higher RPMs?
Proper Car Maintenance is Key
Make sure you are following the recommended fluid changes, and scheduled maintenance. Just doing that can help to prolong the life of your car. Also, try to let your vehicle warm up before putting it in gear and taking off.
When you first start your car, all the oil and transmission fluid is sitting in the pans. Starting your car and then immediately taking off can cause a lot of wear and tear on the engine and transmission.
Let it warm up and allow the fluids to start lubricating everything properly before taking off. It usually only takes about 30 seconds to a minute for newer cars to get warmed up.
Lastly, try not to rev your engine too high, or too often. I know it can be fun to give the car some gas just to hear the engine roar, but doing that too often can lead to premature damage. Try to keep the needle out of the redline as much as possible.
When your car’s engine revs up and the RPMs are increasing but the vehicle isn’t accelerating, there can be a lot of possibilities. Sometimes diagnosing the problem is the hardest thing to do. Check the easiest fixes first.
Make sure you have plenty of clean transmission fluid, you don’t have any loose vacuum lines, and your plugs and wires are good. If these are not the issue, you might have to get a mechanic to diagnose it because the problem could be internal.
It could be a bad clutch, torque converter, dirty throttle body, an intake manifold gasket, or a failing ECM. All of these may be difficult to diagnose without the proper training and tools. Whatever the problem is, we hope you’re back on the road quickly, and without having to spend a lot of money.