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Why Does Your Car Over-Rev While Changing Gears?

Driving a vehicle with manual transmission can prove to be quite challenging for many people. You never know when you make a mistake and hear weird noises from the car. One of the most common noises that you notice in such cars is when you hear your car over-rev while changing gears. We have written this article to help you understand why this problem occurs.

There are a few reasons that you may hear the car over-rev while changing gears. The most basic reason is that sometimes the driver tends to have the accelerator pressed slightly when the clutch is pressed in tandem. If not a driver error, the car can over-rev because of bad throttle position sensors, the throttle cable, or even the valve itself that might be malfunctioning. Other reasons may include a worn-out clutch or the gas pedal potentiometer malfunctioning. Fixing these issues is relatively easy as the concerned component can just be replaced.

Time to look deeper into these issues and find out how they can be solved.

Driver error

Foot on the Pedal
Foot Pedal | Image Credit: Pexels

As discussed above, one of the most common mistakes a driver makes in a manual car is during the gear shifts. They tend to hold onto to the accelerator a little bit and press the clutch simultaneously. This causes the engine to disengage from the wheels. At the same time as the gas pedal is pressed, the engine starts to overrev since there is no load (wheels) connected to it.

Unfortunately, this is not something that you can fix easily. It just takes practice and more practice to get used to the gear-changing action. Remember to slowly change your gear rather than try to be quick about it. Eventually, you will get the hang of it and will be able to do it quickly.

Worn Out Clutch

Clutch Plate
Clutch Plate | Picture Credits: Youtube – HumbleMechanic

Since the clutch is a mechanical component, it is prone to wear. Consequently, over time, the friction lining of the clutch reduces and hence the gripping action. Thus, it takes slightly longer for the clutch to re-engage completely. This leads to driver errors more often since the gas pedal is pressed before the clutch has time to completely reengage.

The solution for this is to simply replace the clutch plate as the lining has worn out. This would reduce the number of driver errors. However, there may be other problems that may cause the car to over-rev while changing gears.

Gas Pedal Potentiometer

Car Pedals
Pedals | Picture Credits: Pixabay

If you are certain the problem is not a driver error, then you might have a problem with the gas pedal potentiometer. In new cars, this sensor essentially detects how much the driver pedal is depressed. If the sensor is malfunctioning, then the car will read that there is a demand for more gas from the driver even if your foot is completely off the pedal.

A quick way to confirm this problem is to observe the behavior of the car under idle conditions. If the car is over-revving in neutral gear with your foot completely off the gas pedal, then this might be the problem. To solve this, you will either have to recalibrate the throttle position sensor or completely replace it – depending on the severity of the problem.

Throttle Cable

Throttle Cable
Throttle Cable | Image Credits: Youtube – Engineering Explained

In older cars, the work of the gas pedal potentiometer was done by the throttle cable. The tension of the cable dictated how much the throttle valve should open. Since this was mechanical, it was subject to wear over time. This led to similar problems of the car overrevving even if you didn’t press the accelerator during changing of gears.

To fix this, you will have to adjust the tension in the throttle cable accordingly and calibrate it to allow the throttle valve to function as designed. This can easily be done at home. But, if you are unsure about it, you can ask a local mechanic to take a closer look. Once fixed, your car’s over-revving problem should be solved.

Throttle Position Sensor

Throttle Position Sensor
Throttle Position Sensor | Image Credits: Youtube – EasyAutoFix

A sensor monitors the opening of the throttle valve after the ECU has determined how much of the throttle valve is to be opened. Accordingly, it adjusts the opening as required to meet the requirements set by the driver while trying to operate at an optimum point. If this sensor malfunctions, then the ECU doesn’t get correct position information about the throttle position. Thus, it tries to rectify it often leading to a wrong angle ultimately and thus probably a higher airflow.

This problem has been noted in several models from multiple manufacturers. The solution in such cases is to first check the connection to the wiring harness. If this is done properly, then you have to just change the entire throttle position sensor.

Throttle Valve Issue

Throttle Valve
Throttle Valve | Image Credits: Engineering Explained

Sometimes, the problem is with the throttle valve itself. Over time, dirt, debris, and carbon soot accumulate near the butterfly throttle valve. This causes the throttle valve to be stuck open at a particular angle rather than completely closing. There is a high chance this is during the idling conditions where the valve is supposed to stay closed. But since it stays open slightly, it causes over-revving.

To check for this problem, you just have to take out the throttle valve from your car’s engine and check the valve from both sides. You have your answer if you notice a lot of dirt and carbon deposits. You could try to clean the soot and debris yourself. However, you must be careful not to scratch the inner lining of the valve. This might lead to vacuum leaks down the line.

If you feel this might be a bit challenging, you can ask an auto technician to clean it for you. Alternatively, you can completely replace the throttle valve entirely. This should solve the problem.

Final thoughts

There you have it, a list of problems that might be causing your car to over-rev while changing gears. As you can see, most of them can be solved rather easily. As for driver errors, it is important not to let such minor incidents shake your confidence. All you need to do is keep driving and eventually you’ll get the hang of it! We hope that this article helped you and that you don’t get scared the next you hear your car go “vroom” loudly out of nowhere.


Abheek is an Engineering student with a background in Automotive Engineering and Sustainable Energy Engineering. He has worked in Engine Development for a couple of years but is quite interested in Electric Vehicles too! In his free time, he likes to use his knowledge to help others with their car problems. Other times, he can be found following the sport of Formula 1.

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