Skip the auto shop - Our mechanics make house calls

Q: When I stop at red light RPM drops and feels like it going to shut off

asked by on

No check engine light on. Changed spark plugs. Car drives awesome. But when i stop at light rpm drop to 500. And feels like its going to shit off.

My car has 80455 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 recommend having a professional 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!
  1. Home
  2. Questions
  3. When I stop at red light RPM drops and feels like it going to shut off

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: Stalling at stop lights

Hello there, a few different faults could be causing your 2000 Plymouth Breeze to stall. The most common would be the fuel pump, MAP sensor, fuel filter, battery, alternator, battery cable, or a wiring fault. To have all these items...

Q: High idling, car jumps when put into gear

When the vehicle surges such as what you have described and has a high idle, they are generally related. A few different items can cause this fault such as the MAF sensor, a vacuum leak, a throttle body fault, or...

Q: I have a smell coming from under the hood when I turn the heater on.

Hi there. The smell would be the cabin air filter causing the odor to fumigate the area. Find the cabin air filter and replace the filter with a new one. Usually the filter is found in a trap door behind...

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...