Why Is Your RC Car Moving By Itself? A Troubleshooting Guide

Have you ever found your RC car moving by itself? I’m sure you know the feeling of your heart dropping as you see your RC car racing off towards some random solid object. That will definitely be enough to ruin your day, especially if you don’t know how to resolve the problem and put full control back into your hands.

So why is your RC car moving by itself?

The primary reasons are as follows:

  1. There’s interference in the area. (Usually on 27 and 49MHz range)
  2. The carburetor gap might be too big.
  3. The battery pack that runs the electronics could be faulty. (If you have a nitro RC car)
  4. Corrosion on the terminals and wires in the RC or transmitter.
  5. Faulty Transmitter or Receiver
  6. Faulty Servos. (Normally stops the RC from moving but can make it roll a bit automatically)

Of course, depending on what type of RC car you have, not all of these potential problems will apply to you. So throughout this troubleshooting guide, you can just go through the relevant checks for your specific RC type. We’ll go from the smallest RC car types to the biggest.

We’ll look at every potential problem as per the list above and advise on how you might solve each problem. Let’s start on the most basic and cheapest RC cars which use infra-red and then move upwards from there.

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Whenever you test your RC after making an adjustment, place the RC on a secure stand so that the wheels don’t make contact with anything.

  1. Interference in the area. (Usually on 27 and 49MHz range)

1.1 Checking for Infra-Red receiver interference

With Infra-Red RC cars, most types of bright light will interfere with the control of your RC and can make it move forward by itself. Even if it’s a cloudy day outside, the sunlight coming through the clouds can interfere with your Infra-Red Reciever.

Related post: Is Your RC Car Faster in Reverse? This Might Be Why

Troubleshooting steps:

Try testing your RC car indoors under different types of lights to see if it still moves by itself.

You can also test your RC outside your house at night to see if it still moves by itself or not.

If your Infra-Red RC car is still moving by itself indoors under different lights and outside at night then you should just return it to the seller and they will usually swap it out for you if it’s within its warranty.

If your RC is out of warranty it’s possible that the infra-red receiver has become damaged over time. This would be a perfect time to upgrade and move away from infra-red controlled RC’s.

1.2 Checking for 27 and 49MHz interference

These are the common frequencies you’ll find in most basic toy-style RC cars. Because these frequencies are so common in almost all of the cheaper RC cars, there’s a high chance of someone else in the area running the same frequency as you are.

Troubleshooting steps:

If you have a choice of frequencies to select, known as different channels, switch to another channel and check if the RC car is still moving by itself. If the problem still persists, move to the next step.

If you see any people within 150 meters from you, try and extend the distance between you and them so that any possible frequencies they might be emitting won’t reach you.

If there is no space for you to move further away from other people, you can wait 30 minutes or so and then try your RC again. Normally someone who has this type of RC won’t be using it for more than 30 minutes considering the typical battery life of this range of RC.

If none of these steps help, carry on checking through this article for more troubleshooting advice.

1.3 Checking for 2.4Ghz interference

If you’re using a 2.4Ghz system you don’t need to worry about checking for interference. There’s almost a 0% chance that you’ll have other signals interfering with this frequency. Rather look at alternative solutions below to figure out why your RC car is moving by itself.

  1. The Carburetor Gap Might Be Too Big.

If the idle gap in your carburetor is set WAY too big, fuel will pass through it too fast and it will cause your RC to race off by itself and won’t stop until it’s hit something in its path. Depending on the size of your RC, your carburetor opening gap should be set with an opening gap of around 1mm (check your operating manual for exact figures)

Check out this post: How Fast Is A 2.4 GHz RC Car?

For closing your carburetor gap, remove the air filter from the carburetor and then also remove the restrictor before checking the gap size. Look straight down into the carburetor for the gap and not at an angle. You will open and close the gap in the carburetor by turning a flat head screw. You can hold a plastic-coated paperclip at the opening where the gap is going to end up and then close the gap until you just touch the paperclip. A plastic coated paperclip is around 1mm.

Instructions on this for your specific RC should be inside the operating manual and because different models will require slightly different settings, it’s best to check up on what your specific manufacturer suggests.

  1. The Battery Pack That Runs The Electronics Could Be Faulty.

It might sound strange to say that the batteries could be the cause of your RC car moving by itself but it’s true, weak or dead batteries can mess around with your RC and make it move when you’re not controlling it to do so.

Make sure your batteries are fully charged or if you’ve used the full life cycle of the battery, you’ll have to buy some fresh ones. You can ask the manager of the hobby shop if they can test out different batteries with your RC before buying new ones without knowing for sure if that’s the problem.

  1. Corrosion On The Terminals And Wires In The RC Or Transmitter.

Corroded electrical wires inside the transmitter can interfere with your RC movement. Usually, corrosion occurs when moisture gets inside the transmitter. The same goes for the RC and receiver, if the electrical wires are corroded by any liquid they can cause the RC car to act strangely. Normally this will only cause small movements but you will still have to get the wires repaired or replaced.

  1. Faulty Transmitter or Receiver.

Test your RC car with another compatible transmitter to establish if there’s a problem with the transmitter (remote controller) or receiver (inside the RC). You could ask the store owner at the hobby shop for assistance. If the RC is still moving by itself with another transmitter that you know works 100% then you’ll know that the problem exists in the RC itself. If the RC stops moving by itself when using a different transmitter, your transmitter needs repairing or replacing.

  1. Faulty Servos.

The servos in your RC car are the little components that convert an electrical signal into movement. They tell your RC when to move and how to move.

Most of the time defective servos will result in a lack of movement in the RC rather than an automatic movement, but in some cases, a slight automatic movement may occur if you have faulty Servos.

How to check the servos:

A basic inspection can be done by moving the unplugged servos in both directions gently to their limits feeling them out for any signs of being stripped, listening for weird noises, and so on.

Related post: Want to Go Further? How to Improve the Range of Your RC Car

It’s best to have the servos checked by a technician who has a servo testing unit and knows exactly how to test them.

Conclusion.

After going through all of these troubleshooting steps, if your RC is still moving forward by itself, take the RC into the hobby shop and show them the problem. Now that you’ve gone through all these steps, you’ll be able to tell the technician about everything you’ve done so that they can eliminate some things off of their own troubleshooting checklist. Even though they might want to double-check some of these things for themselves.

If this article was in any way helpful to you, please check out some of my other content.

Paul Good

This awesome hobby has something for everyone, whether you like to build your RC from scratch and keep modifying till you've got it to just how you want it, to track racing. You might be out with a boat, or perfecting your skills with a plane. Are you taking some cool pics with your drone? I'm sure my site will help you on your journey.

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