Why does the engine have high RPM before automatic transmission shifts?

In automatic cars, transmission is how power is taken from the car’s engine to the wheels. Transmission helps you to move your vehicle forward on the roads.

Transmission achieves this by shifting gears to control an automobile effectively. The best thing about automatic transmission is that instead of shifting the gears manually, the system moves the gears automatically for you.

However, there are some cases where the automatic transmissions shift at high RPM that include transmission fluid problems, faulty speed sensor, and faulty idle control valve.

The car’s automatic transmission is an autonomous system, which does not require the driver to engage the gears. In fact, in these cars, there is no clutch pedal.

The birth of the device dates back to the early 40s when in the United States, it was mounted on some Oldsmobile models. However, it only took hold in 1950, when it was fitted as standard on some cars produced by General Motors and Chrysler.

Subsequently, the automatic transmission also arrived on the European market, remaining an option available on some high-end machines, while today it is widespread and present on a large number of vehicles, especially in a city ​​car with automatic transmission for city driving.

The RPM means revolution per minute. It describes the number of times the crankshaft rotates on its axis in one minute. The piston moves down and up during the combustion, and the energy generated is transferred to the vehicle’s crankshaft.

Sometimes, problems in your automatic car can make your transmission shift at higher RPM than usual. This commonly results in increased fuel consumption since more strain is directed on your car’s engine, but also other problems.

Below are some of the causes of high RPM when you are driving.

Transmission fluid problems

The transmission fluid is used to transmit power from the engine to the transmission. This fluid is also essential for lubricating your car’s transmission system.

Your car starts to rev at a higher rate when the fluid starts to leak due to gearbox band or torque slippage. Some other signs of leaking transmission fluid are erratic or delayed gear shifts.

To solve this problem, you are supposed to replace the fluid with a new one and ensure no leakage and also to fix other causes of leakage, if any.

The cost of replacing the fluid is about $250, including the labor, but the costs of repairing other causes of leaks vary.

Faulty speed sensor

Automatic cars use speed sponsors to know if the gear should be shifted. Your vehicle may fail to shift the gear properly if the speed sensor cannot accurately sense your car’s speed.

As a result, a faulty speed sensor causes high rpm before shifting since the engine has to work harder. The solution for this problem is to replace the defective speed sensor with an operating speed sensor.

The cost of buying a new speed sensor depends on the model and make of your car, but the average price, including the labor, can start from $200.

Faulty idle control valve

A problem with the idle control valve can be sensed if your car has a high RPM when idling. The function of an idle control valve is to maintain a specified rpm when the vehicle is idling.

If the blown fuse of the valve is faulty, the valve will stop working altogether, but this is an easy fix since you just have to replace the fuse.

To replace the faulty idle control of your control valve with a new one. The average cost of installing a new idle control valve with the labor included can vary on the make and model of your car.

At what RPM should an automatic transmission shift?

The level of the RPM at which the automatic transmission should shift entirely depends on your driving style since the car will shift differently depending on your style of driving, but also on how you set the automatic transmission, and by this, I am referring if your automatic car has the feature to let you put the transmission in sports mode.

There are a lot of automatic cars that have this feature so shifting at a higher RPM is totally normal here.

Also, your vehicle will tend to change at a later RPM if you drive aggressively. Your car will also not shift if you hold the throttle pedal down until you’re close to the redline.

The pedal will shift very early if you depress the pedal. Your automatic transmission should range between 2000 RPM to 2800 RPM on normal driving, where the acceleration is normal.

You should check the fluid condition and level if your car is shifting very early or late. If the fluid condition and status are okay, you should check the other issues.

Can high RPM damage transmission?

Although very low RPM and high loads can damage the transmission, a sustained high RPM can also damage the transmission over time.

The higher the RPM, the more the wearing of the oil seals, bearings, and quicker transmission fluid breakdown. During high RPM, the transmission oil pump overheats the fluid by sharing it between the gear teeth of the pump.

The same happens with the torque converter, although it is not very likely provided that the car is moving. You can minimize these negative impacts by adding anti-wear additives and a good cooler for fluid transmission.

In automatic cars, is it normal for the RPM to be high?

Yes and no, it is not normal for automatic cars to have extremely high RPM in normal driving conditions. However, if the transmission is set to sports mode, then it’s normal for the gear to be shifted at a higher RPM.

Conclusion

The automatic transmission is quite simple. The system manages the gear ratios by itself through a series of mechanisms such as the torque converter and the actuator.

Depending on the type, the automatic gearbox can be hydraulic, operated by a high-pressure fluid, or electromechanical, controlled in this case by an electronic microprocessor.

Several causes can make your automatic transmission have high rpm before shifting. As we have seen in this article, transmission fluid problems, faulty speed sensors, and faulty idle control valves are some of the reasons why automatic transmission has high rpm before shifting.

Making the necessary repairs require skill and knowledge, so I advise you to go to an authorized repair shop to do these repairs.

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