Q: My car idles rough when I have my foot on the brake at a stop light

asked by on

Rough idle with foot on brake at stop light or just sitting in park in driveway runs good while driving

My car has 128000 miles.
My car has an automatic transmission.

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 failing, your vehicle will stall instead of slowing to an idle after the release of the throttle. I would recommend having an expert, such as one from YourMechanic, come to your home to replace your idle air control valve.

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. My car idles rough when I have my foot on the brake at a stop light

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: Lost all transmission fluid near radiator overnight 2004 GMC Sierra

Hello - there are fittings at the radiator where the transmission oil lines go into the radiator side tank. Perhaps one or both of these fittings came loose, or broke - leaking fluid from that point? Gravity would do the...

Q: loss of power sluggish

I recommend inspecting, then cleaning the throttle body if any deposits are found. It's important to do this with key off and disconnect the electrical connector to throttle body. Do not put your fingers in there until it is connected....

Q: Gas gauge malfunctioning and Service Engine Light on

Thank you for asking about your 2006 GMC Sierra 1500 HD. More than likely, the problem is the fuel sensor, which is built into the fuel sending unit. This assembly is mounted in the gas tank. This is a common...

Related articles

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.