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: 2010 Chevy Tahoe, no crank no start somedays. open/close fuse box crank up. driving stable track, and service traction control

There are a large number of Technical Service Bulletins (TSBs) published by GM relative to the Tahoe's electrical system. In fact, the number is the largest I can recall from recent checks of the variety of other models we deal...

Q: Q: Headlight not working properly.

A flickering headlight means one of two things. Either the headlights is faulty because the filament inside has broken and is intermittently making contact, or there is a problem in the electrical supply for the bulb such as a bad...

Q: Every time I put my key into the ignition lights flicker, radio comes on, and check engine light comes on.

Hi there. There is an issue with the ignition switch when you are turning the key. The tumbler may have worn contacts within the switch causing the lights to flicker and the radio to come on when it is turned...

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...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...