What Causes High RPMs While Driving? Causes and Fixes

Discovering what causes high RPMs while driving can be dicey, as it could result from several mechanical faults. It could be that you’re using the wrong gear, worn-out spark plugs, or a faulty throttle body.

What Causes High RPMs While Driving

When this happens, your Revolution Per Minute (RPM) becomes too high and causes engine overheating. If you’ve been experiencing this problem, our complete guide highlights the possible causes and how you can effectively resolve them.

What Causes High RPMs While Driving?

The causes of high RPMs while driving include a worn or slipping clutch, dirty fuel injectors, a faulty idle control valve, and malfunctioning throttle pedal position sensors, among others. Another major cause of high RPMs while driving or accelerating is vacuum leaks.

This disrupts proper pressure in the engine, causing it to overwork itself. Other causes of high RPMs while driving or accelerating include dirty or clogged injectors, worn or slipping clutch, bad throttle, and defective speed sensors. Blocked air filters, catalytic converters, and bad plugs can also cause an increase in RPM while driving.

Although not limited to these, here are the possible and most common reasons your RPM is high.

-Worn/Slipping Clutch

If your car uses a manual transmission system, you’d most likely use a clutch to aid transmission. When your clutch is worn or slipping, the amount of pressure your clutch pedal needs is reduced. The result is that your engine will automatically struggle to make up for this lesser pressure by revving higher, which will then cause it to overheat.

Dirty Fuel Injectors

An injector supplies fuel to your car’s engine cylinder via a nozzle. Over time, this injector becomes clogged with dirt and particles. When this is the case, there’s a high chance that your injector won’t spray the right amount of fuel. It may also disrupt the intervals at which fuel should be released into the engine.

Unclean injectors will cause your engine to rev high and increase RPM since the engine isn’t getting enough (or getting too much) fuel at the right time. Once this happens, your vehicle’s RPM will constantly change instead of remaining the same while driving. At this point, you may also notice that your car jerks, requires more stops at the gas station, and emits a sulphuric odor.

– Faulty Idle Control Valve

If you notice your RPM getting high while driving, it may be an indication that your idle air control valve is faulty. This car component regulates the car engine’s idle speed. A bad idle air control valve is responsible for increasing or reducing your idle speed where necessary.

You may experience rough idle speed if it goes bad. This means your engine speed becomes unusually high or low, increasing your RPM since your engine is working overtime to maintain a consistent speed.

– Vacuum Hose Leaks

Vacuum hose leaks are perhaps one of the most common reasons your car’s RPM fluctuates. The vacuum hose plays a crucial part in your car’s transmission system as it helps to maintain just the right amount of pressure within your engine. A vacuum hose makes it easy for air and fuel to properly combust and work hand in hand for the smooth running of the vehicle.

In the case of a leak, your engine starts to experience glitches due to a change in proper pressure. With a vacuum leak, an unnecessary amount of air is introduced into the engine, disrupting the normal combustion process. When this is the case, your RPM will increase or become sporadic since your engine is struggling to function properly.

At this time, you’d notice your tachometer needle moving irregularly, getting too high and low at intervals. If not looked into quickly, the leak can cause irregular RPM surges and send your engine into overdrive.

– Malfunctioning Throttle Pedal Position Sensor (TPS)

The TPS is easily one of the most important parts of a vehicle. It works just like a throttle body which controls the movement/transmission of your car by interacting with the mass airflow sensor and engine RPM. Through this interaction, the TPS ensures that the right amount of air and fuel is delivered to the car engine. When you have a faulty sensor, you will notice many issues coming up.

Since the TPS isn’t working as it should, the right information isn’t communicated to your car’s onboard computer. Your car engine has to work on its own to compensate for this lack of information. Aside from the car jerking, stalling, or refusing to pick up speed, one major symptom of a bad TPS is an increase in RPM.

At this point, you’ll notice your car begin to speed up unexpectedly, even without using the accelerator. When you experience this unusual burst of speed, it means your throttle body has been closed up for a while and unexpectedly opened again.

– Faulty Speed Sensor

RPM fluctuations often occur when you have a faulty speed sensor. Speed sensors are only found in automatic cars. A speed sensor works by helping your engine determine when to shift gears. Once your speed sensor becomes defective, there’s a high possibility of an increase in RPM.

Since your transmission system can’t shift gears accurately, your engine works twice as hard running at a higher speed than required. Another way to know if your speed sensor is the cause of high RPM is that changing gears becomes rougher, especially when you are trying to accelerate.

Bad Spark Plugs

Your car’s plugs are another important part of its transmission system. These aid easy car ignition without putting too much pressure on the engine, which in turn helps to maintain your RPM level. When your plugs become faulty, the chances of experiencing a surge in RPM are high. If the plugs do not produce the right amount of current needed for proper ignition, the load on the engine increases beyond the norm.

Excess load on the engine causes it to rev more than necessary since it is trying to make up for low current. Also, using worn-out plugs over time causes your engine to overheat, leading to high RPM and low mileage.

Other things that cause high RPM while driving include overspeeding, timing trouble, clogged air filter, and a defective engine cylinder. You may also notice this surge in RPM as a result of a bad tachometer (RPM meter), damaged carburetors, and a jammed catalytic converter.

How To Fix High RPMs While Driving?

To fix high RPMs while driving, you can try driving slower, cleaning or replacing the fuel injectors, changing your car’s gear, or checking the spark plugs. Now that you’ve identified some possible reasons why your RPM fluctuates, here are the simple solutions to resolve this problem.

– Drive Slower

One of the ways to reduce your RPM’s fluctuation is by trying to drive slower, especially if your car uses an automatic drive. Since overspeeding is a cause of high RPM, you may need to step less on the accelerator while driving. Sometimes, continuously stepping on the gas pedal sends information to the engine that makes it try to match up the speed being operated. The effect of this is that the engine easily gets worn out from working overtime to keep up with the accelerating speed of the car.

Since you can’t change gears with an automatic car, you can prevent high RPM by removing your feet from the gas pedal at intervals. When you do this, your engine will work less hard, and you’ll notice a significant reduction in the RPM.

– Clean or Replace Fuel Injectors

Since unclean injectors are part of why high RPMs increase while driving, you need to pay attention to them. They make your RPM spike due to an irregular amount of fuel coming into the engine, so you’ll need to clean it as often as possible. Ideally, we advise that you take time to clean your injectors between intervals of three weeks and two months.

Once your injectors are free of blockage or dirt, it becomes easier to supply the right amount of fuel when needed. If you still notice that your RPM is getting higher after cleaning the injector, you may have to replace the injector with a new one.

– Change Your Car’s Gear

Another way to ensure you have a stable RPM while driving is to change your car gears at intervals. This applies to those whose cars use a manual gearbox. If, for instance, you’ve been driving at high speed for a while, you may need to downshift your gear at intervals to ensure your engine is working less. By doing this, you will reduce the car’s RPM significantly.

– Check Spark Plugs

If you notice an unusual surge in RPM while driving, check to ensure that you do not have bad plugs. It is important to note that sometimes the actual plugs might not be the problem. If this is the case, then you may need to inspect the spark plug wires for defects.

If you discover the plug or plug wire is the issue, you’ll have to replace them with new ones. Although you can do this yourself if you have technical knowledge, we recommend that you reach out to a professional mechanic for more precision and efficiency.

Other methods you can do to fix the issue of high RPMs while driving or accelerating include checking your transmission fluid and cleaning your air and fuel filter. You should also promptly replace the faulty throttle, tachometer, and speed sensor if any of them are diagnosed as the problem.

Frequently Asked Questions

1. What Should Be My Normal RPM While Driving?

A normal and ideal RPM while driving is usually between 1,500 to 2,500 revolutions per minute if you’re accelerating at a normal pace. However, there might be an increase in RPM when you’re speeding or when there’s an underlying mechanical fault.

2. Why Isn’t My Car Accelerating but Revving High?

Your car is revving high without accelerating because it may have a faulty TPS, or throttle pedal position sensor. Your clutch may also be worn out or slipping. Other possible causes include insufficient or dirty transmission fluid, clogged filters, and a faulty engine control module.

3. How Do I Increase My Car’s RPM?

You can effectively increase RPMs by shifting gears, from a lower to a higher gear when necessary, but this only works if you drive a stick shift. If you use an automatic transmission, you need to step on the accelerator pedal and apply significant pressure.

4. Can Low RPM Harm My Engine?

Yes, low RPMs can cause damage to an engine. If your RPM is low while driving, your engine struggles to increase your car’s speed. In the gradual process of trying to increase the car’s speed, the engine temperature and pressure in its cylinder will likely increase.

When this happens, the engine overheats, and if left unfixed for a long time, it can cause severe damage to your vehicle’s engine.

5. What Is the Reason for My Car RPM Fluctuating?

The most common reasons that your car RPM is fluctuating include vacuum hose leaks, dirty filters, and dirty or clogged fuel injections. Other reasons include defective engine cylinders and a malfunctioning timing belt, so it would be best to have a professional diagnose the problem.

Conclusion

Now that you know what causes high RPMs while driving, identifying the ones that apply to you and fixing them becomes easier. Here’s a quick rundown of the key points discussed in this article:

  • What causes high RPMs while driving includes a slipping clutch, faulty TPS, or speed sensor.
  • Easy ways to resolve this issue include replacing worn-out plugs and wires, changing your car’s gear, fixing your speed sensor, cleaning your injector, and replacing what damaged parts and hardware.
  • Other ways to fix the problem of RPM fluctuation while driving include cleaning dirty air filters and repairing or replacing bad engine cylinders and damaged carburetors.

Knowing the causes and solutions for high RPMs while driving will save you time and prevent dangerous situations from happening. Before concluding on a cause and solution, we advise that you consult a professional mechanic for verification.

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