why does my car idle high then low

Today's advanced computer monitored and controlled fuel systems might seem complex, but the components that operate them have not changed much over the years. Whether your car is a classic or fresh off the dealership lot, a common problem car owners experience is an engine idle that just doesn't seem right, either upon start-up or during normal operation. There are several factors that determine engine idle speed. Listed below are a few of the components that control or cause engine idle speed to be high or low and ways you can resolve these problems. Engine idle refers to keeping the engine running when the vehicle is not in motion. Generally, idle speed is just enough to keep the engine running without stalling out. The average engine idle speed for production cars, trucks and SUV's sold in the United States ranges from about 900 to 1,100 revolutions per minute (RPM). Occasionally, the engine RPM will be higher or lower than this average for multiple reasons. Some performance engines, such as those installed in racing engine, are designed to idle higher than average. In general however, there are two problems that can cause engine idle speed to fall outside of specifications:
Issues with the It's best to have a professional mechanic to pinpoint the exact reason. On a modern fuel injected engine, engine idle is controlled by the engine control unit (ECU) and an electrically operated throttle control module. When the idle is high or low, it could be caused by a malfunction of this system or any of the individual components that comprise the system.


The idle air control valve controls the idling of the engine by allowing a determined amount of air to mix with liquid fuel and create a vapor to be burned in the combustion chamber. When it fails or begins having problems, the impact will change the idle speed of the engine. There are a few other engine components that can have an impact on engine idle speed including the following: The intake gasket is designed to maintain a consistent pressure inside the engine. When the gasket fails, it can allow pressure to escape, which tends to cause elevated idle issues. Vacuum lines: Used to control the internal vacuum pressure inside the motor, the vacuum lines, like the intake gasket above can cause elevated idle issues if they are broken or not properly attached. Air intake: The job of the is to move air into the engine. When itвs damaged, more air can pass through, which will cause the engine to idle high or low. A damaged throttle bore will result in the same problem, because itвs no longer able to regulate the volume of air flowing into the engine. PCV valve: The or crankcase ventilation system removes vapors from the engine. When it doesnвt work correctly, the engine may idle at various speeds. *Engine timing: The idle speed also comes from. When it isnвt timed correctly, the result is an engine that idles too fast or too slow. All of these components can cause a problem with idle speed when they donвt work correctly. If your or too slow, a technician needs to inspect the system to determine which component is at fault.


An engineБs idle is like the heartbeat of the human body. Just one abnormal or unusual sound, and you know that there is some problem with it. Cars tend to idle high, low, or rough. But in this article, IБm only going to talk at length about the most frequently asked question. Why does my car idle high? A problem under your vehicleБs hood is not good news. During such times, the chances of the carБs idle speed along with quality being subjected to damage are highly likely. This means that issues related to idle speed are warning signs. So letБs find out the causes and everything else you need to know about idle speed problems. More. Car idling high when driving or starting has several causes. But before we get into them, thereБs something else you ought to know. At present, our advanced computer and fuel systems seem complicated, donБt they? But the truth is that the components involved in operating them are pretty much the same as they were a few years ago. So it doesnБt matter if you have a classic or a new vehicle from your dealership lot. Many car owners have to deal with engine idle. More often than not, the idle doesnБt seem like its true self. This is a common occurrence that you might face while driving or when starting a car. Several factors are involved when it comes to determining the speed of an engine idle. And below I have discussed all of these components. They are responsible for controlling or causing the speed of the engine idle to shoot up or dive down.


I have even listed the different ways that you can adopt so as to resolve such kind of issues in the most efficient manner. What are the Causes of the Car Idling too High? Modern fuel engines come with an ECU (engine control unit). This particular component is responsible for controlling the motor idle. Even the electric throttle control feature is used for the same purpose. So what does this tell you? That any malfunction in these two systems or the components that house the systems might cause the idle to rise or lower. The valve that controls the idle air does an excellent job at handling the engine idle by performing the following function. It allows only a certain quantity of air to combine with the liquid fuel. And this creates a vapor that burns in the carБs combustion chamber. So when such activity fails to occur, it tends to mess with the engineБs idle speed. But there are a few more engine components that can give rise to high idle when starting a car. LetБs find out! So these are all the components responsible for controlling idle speed. And this means that they need to work correctly. So if your engine is idling slower or faster than it should, you ought to get your technician involved. This reminds me of the time I had some issues to deal with my that I installed in my car a few years back. I tried to do the inspection myself, but that didnБt get me anywhere. So I had to hire professional help to solve the problem quickly and most efficiently.


DonБt hesitate to do that if your car is idling high. The sooner you address the problem, the better it will be for your vehicleБs engine in the long run. So now do you know the answer to why does my car idle high? Dealing with idling problems is quite frustrating, isnБt it? But all you need to do is identify the cause of the issue. Once you do that, figuring out the correct solution wonБt take too long. So please make it a point to check the engine idle regularly. But do so with the defroster and AC turned off. Otherwise, they might interfere with the idle speed. Have you ever had to deal with an issue like this? Does your engine idle high or low? Tell us all about your experiences and how you tried to solve such issues related to idling. The more reliable information we have, the better solutions we can come up with. I hope you found the article interesting and informative. And most importantly, did it help in solving your problem? Do leave your comments and feedback in the section below. Thank you for visiting. Have a great day! Christian Olsen is the founder of. He writes articles about all kinds of devices that we use on a daily basis. His goal is to cover all types of topics with transparency, honesty, and cheerful enthusiasm. Articles created by him have not only product reviews but also useful tips about the daily struggles of using technology. And he has a knack for relating everything to his personal experiences to create content that readers can enjoy.

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