Driver And Driving

What Causes RPM To Run High?

Mike Cross
Updated Feb 8, 2022
What Causes RPM To Run High

Few things strike fear in a driver, and having a car that has RPMs run high is one of them. It can be very disconcerting to be sitting at a stop light and have your car’s RPMs running high. What causes this to happen and should you be worried?

There are a few reasons why your car may be running the RPMs high. It is important to know what is causing this to happen so you can take the steps needed to fix the problem. No matter how bad a problem may seem, it is always best to handle it right away. Doing this will hopefully prevent further damage or problems to your car.

What Causes RPM To Run High
What Causes RPM To Run High?

What are RPMs?

All motor vehicles have RPMs. It stands for Revolutions Per Minute. In a car, RPM measures how many times the engine's crankshaft makes a full revolution and how many times the piston goes up and down in the cylinder.

Generally, when you press the accelerator, the RPMs increase. A car’s tachometer is used to measure RPM. These readings are done in units of 1000. At the top of a tachometer is a red line. RPMs over the redline can cause damage to the car.

Under normal driving circumstances, an automatic transmission will shift at whatever RPM will give the best combination of efficiency and smoothness. Drivers of manual transmissions have to learn this sweet spot for themselves. However, in newer manual transmission cars there is a rev limiter. This helps prevent the engine from running into that redline.

Reasons why your car may have high RPMs

Vacuum Hose Leaks

There are a lot of hoses under the hood of your car that help deliver both fuel and air to the internal combustion chamber. If you have a problem with a vacuum hose, it can cause rough idling in your car.

The hose could be damaged, loose, or worn out, which winds up creating a leak. This leak could result in an abundance of air mixing with the gasoline, which would result in a misfire. This could cause a car to idle rough and have a higher than normal RPM.

Transmission Issues

Transmission Overheating Symptoms And Causes

Your car could have a problem with the transmission, or if you have a straight shift, it probably means the clutch is slipping. If your car has an automatic transmission, the shifting is often done by hydraulic pressure based on engine speed.

If the transmission system is having problems, it may require high engine speed to shift to the next gear or it may not shift to the next gear at all. This can cause your car to rev at higher RPMs than usual. you can use this tool to find the problem on your transmission.

Clogged Air Filter

Your car’s engine needs air from the outside to mix with the fuel in the internal combustion chamber. All cars have an air filter, which prevents debris from the air from getting into the chamber.

But if this air filter is clogged or worn out, then there will be less clean air passing through it. This will cause the engine to idle rough. When your engine is idling rough and struggling, it often will rev at higher RPMs.

Clean Your Fuel Injector

Fuel injectors modernized the way in which vehicles deliver fuel into their internal combustion chamber. The only problem is that these fuel injectors can and do get dirty after a while.

If you are not using gas additives or fuel injector cleaners on a regular basis, then you will wind up with a dirty fuel injector. This will result in your car idling rough, and can cause your car to have higher RPMs. You might also notice that your gas mileage decreases as well.

Check The Spark Plugs

Spark plugs are a small part of our car, but they have a big impact. If you have bad spark plugs because they’re worn out or damaged, then it could be causing your engine to be idling rough.

Spark plugs are used to send a current of electricity into the internal combustion chamber to ignite the mixture of fuel and air. If the spark plugs are bad, then the electrical current won’t be sufficient enough for the ignition. This will cause the fuel and air mixture to burn inconsistently, which will result in a rough engine idle.

What Can You Do?

Reasons Manual Transmission Wont Go Into Gear When Running And What To Do

It is crucial to your car’s well being that you do not let it rev at high RPMs. This will cause damage to your car’s engine and transmission. If you have a bidirectional scanner at home, plug it in. This is a good starting place when trying to figure out the root cause of higher RPMs.

As soon as you notice your car having trouble, take care of it. If you are not sure what the problem is and you are comfortable under the hood you can take some steps to correct the problem.

Check your spark plugs. If they are faulty or worn, replace them. Replace all of them. This way you know that they are all new and working properly. If your filters are dirty, replace them too. You should also check the fluid levels. Make sure they are at proper levels. If the levels are low, top it off. If the fluid is dirty or smells off, it is time to change the fluid.

Regularly using a fuel additive should help keep the fuel injector clean and running smoothly. You can also visually inspect the hoses for any signs of holes or damaged. Make sure you replace any that show signs of wear.

If after all of that your engine still experiences high RPMs, you should have the transmission checked out. It is a good idea to take your car to a professional mechanic and have them check this for you. Most people balk at transmission problems simply because they are expensive to repair.


Do not delay in getting your transmission fixed. The longer you let the problem go, the greater the chance that your car will suffer irreparable damage.

Mike Cross
Life is too short to drive with stock audio

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