Q: Q: Idle fluctuates and then stalls.

asked by on

I recently replaced my battery because the one on it was too small. My car has started to rev up to 3000 RPM and fluctuate, then go to normal. Sometimes it will do it and I have to shut it off. All of this happens while in park. I have noticed that sometimes, while at a light, it idles a little high. I was sitting at a light and it cut off. This has only happened once so far. I'm trying to figure out if it is my idle sensor or throttle, can you help me?

My car has 124900 miles.
My car has an automatic transmission.

What you are describing sounds like a dirty or failing idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about 800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Q: Idle fluctuates and then stalls.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Regarding engine flush 2015 Hyundai Santa Fe

Hi - by "system flush", I understand you to mean a flush treatment of the engine proper, to clean out oil sludge. An oil flush sometimes uses a product called Seafoam to do so. An oil system flush with your...

Q: What name is given to the bearing after the wheel bearing on a 2006 Pontiac Torrent

In your application, the passenger side CV axle does not use a carrier (center support) bearing. The noise you are describing could be due to failure of the same wheel bearing (not a rare occurrence, please read below), or the...

Q: Car squeals and is hard to turn.

It sounds like your belts are in need of adjustment. This is a very common issue on your particular vehicle. Your vehicle has 3 separate belts that run your power steering, air conditioning compressor, water pump, and alternator. If your...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...