Unstable Idling: Causes and Solutions

Also called rough idle, unstable idle refers to the phase of your engine where it is not decelerating normally. This situation can have several causes and be accompanied by other unusual manifestations on your vehicle. In this article, you will learn about the causes of unstable idling, solutions to eliminate them and other possible symptoms on your car!

🚗 What are the causes of unstable idle speed?

Unstable idle is characterized by its range of action. Typically, the rated engine idle speed is 20 rpm... However, depending on the manufacturer, this value may be in the range 750 and 900 rpm... Thus, an unstable idle will have variations of 100 rpm.

The occurrence of an unstable idle speed can be caused by a variety of reasons. It is generally recommended to observe other manifestations of the vehicle, such as:

• . exhaust fumes black : They indicate a problem with engine combustion. This can come from either the air intake system or the fuel injection device. Thus, we are talking about cylinders, injectors, water temperature sensor, air flow meter, air filter, ignition device or even engine pistons;
• . exhaust fumes white : in this case, the exhaust pipe or the cooling system is involved. Indeed, the cooling of the engine may not be performed correctly, and it is possible that the coolant stagnates in some places. In some cases, it is the temperature sensor that causes the appearance of an unstable idle;
• Hood space is defective : You have the option to visually inspect the engine compartment to locate the part of the HS that is responsible for idling the engine. This could be a punctured or disconnected hose, a disconnected electrical connector, or a worn out sensor.

A diesel or gasoline engine can run hot or cold at idle speed. On the other hand, this can be exacerbated during the braking phases or when the headlights are switched on in the event of a malfunction. electronic problem.

👨‍🔧 What are the solutions to eliminate the unstable idle speed?

As you can imagine, unstable idling can be the result of several problems on your vehicle. To eliminate this irregular idling, you can choose from several different solutions depending on the situation:

1. Un diagnostic electronic : With the help of the diagnostic case, the professional will be able to read the fault codes detected by the car computer. Then, depending on the observed codes, you can change parts or reprogram the computer;
2. Variable pressure control : It is necessary to check the hydraulic pressure as well as the compression pressure of the engine. If they are not at the recommended value, it will be necessary to perform several operations to restore them to the correct level;
3. Battery check : It is also possible that the alternator is no longer supplying the energy required by the vehicle. In this case, it is necessary to check the battery as it is probably discharged;
4. Changing the ignition system : This only applies to vehicles with a gasoline engine, the ignition system must be replaced if damaged.

If you are experiencing unstable idling, it is best to contact a mechanic to find the source of the problem. Don't wait to go to a mechanic because unstable idling will lead to regular stops and change the driving comfort of your car.

⚠️ What other symptoms may accompany unstable idling?

You can imagine it, but intermittent idle never manifests itself on its own. Indeed, this is very often accompanied by other symptoms warning the driver of an engine malfunction. In total, there are 3 additional signs of irregular engine idle speed:

1. Car that hurts : it will no longer be able to accelerate properly and will lose power. This often occurs in addition to engine jerking during acceleration;
2. Engine stalls : the engine will stall more and more often while you are on board, regardless of the engine speed;
3. The diagnostic warning lamp on the instrument panel comes on. : This warning light is only present on vehicles equipped with a computer controlled injection system. Its role is to inform the motorist of an injection problem that needs to be diagnosed through diagnosis.

An unstable idle speed reflects a general malfunction of your engine at the air intake or fuel injection level. This could be due to a problem with the amount of air or fuel, poor pressure regulation in the hoses, or even insufficient engine cooling.