Skip the auto shop - Our mechanics make house calls

Q: Sputter when idle

asked by on

When stooped at the light the truck shakes and sputter as if it's shutting off but doesn't. also it sounds as if the gas pedal is being pressed.
My car has an automatic transmission.

A: This may be a sign of a failing idle air co...

This may be a sign of a failing idle air control valve. The idle air control valve is located on or near your intake manifold that monitors the air intake as it is mixed with fuel prior to being injected into the engine. This valve is controlled by the vehicle's computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage.

When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. However, when the engine RPM drops below the normal range of 800 RPM (for most cars), it is more than likely that you are dealing with an IAC valve problem. In cases where this valve is clogged or is nearing its replacement age, your vehicle will stall instead of idling after the release of the throttle.

If you need to get this fixed, I would recommend having an expert from YourMechanic come to your home to replace your idle air control valve.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: My car is losing all engine power off and on when driving

Hey there. With a problem like this, it is a great idea to start with the fuel system. The fuel pump and filter should be checked. These need to be replaced together anyway. Depending on how many miles are on...

Q: Car sputtering when I let off gas pedal

It sounds like you have a fuel-to-air ratio issue. Anything from the idle air control valve to the oxygen sensor may have a malfunction. Diagnosis would be required before changing parts. YourMechanic can send a qualified technician out to your...

Q: Car starts fine, sputters even when giving it gas, shakes and dies, sometimes there's a clanging in the engine

Hi there. Sounds like the engine is not getting enough fuel as if the fuel pump is not working. The engine will start normally and then die off when you give it gas. Check the fuel pressure when the engine...

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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.