Why Do Cars Idle at a High RPM When It's Cold?

One cause for concern many drivers have during winter is seeing their vehicles have a high RPM when starting the car. This can be troubling to see simply because it is out of the ordinary. Fortunately, there is a simple answer for why this phenomenon occurs.

Why Does It Happen?

High RPMs in the cold is a result of combustion taking place in the engine. Your car is able to start because gasoline and air are coming together to form a spark. This spark is only possible if fuel and air are combined with the right timing and proper ratio. Gasoline vaporizes much more easily in warmer temperatures to get that spark.

In colder temperatures, fuel is more likely to get bogged down and thicken. Therefore, the vehicle overcompensates for this by producing a higher RPM initially to move gasoline more quickly. As soon as the vehicle turns on, the RPM goes back to normal, but that initial bump in RPM speed can take some drivers by surprise.

Is It Normal?

You have absolutely no reason to fear if your vehicle produces a higher RPM in cold weather. This is a perfectly normal occurrence. It is simply something your car needs to do so that it can start properly. You should not be concerned if your car jumps up to 1500 RPM and then shortly afterward goes back down to a normal 800 RPM.

When Should You See a Professional?

If your car starts at a high RPM and then goes down when you are actually driving, you have no reason to worry. However, if your car starts high and remains that way throughout the remainder of your commute, then that is cause for concern. This could be an indicator that you have a vacuum leak inside your vehicle, which needs to be addressed, as it could lead to internal damage within the engine. Other culprits for why this occurs include:

  • Broken vacuum hose
  • Broken vacuum booster
  • Broken EGR valve

Ultimately, there is no reason to freak out when you see your car with a high RPM as soon as you start your vehicle in cold weather. It will likely decrease within a few minutes. However, if you are truly concerned for the well-being of your vehicle, then you can take it to a service center to get it checked by a professional. A qualified technician will let you know if there are any underlying issues that should be addressed.