Skip the auto shop - Our mechanics make house calls

Q: Rough idle and sputters while driving

asked by on

my suburban runs great cold for about 10 mins and it slowly drops rpm and and then soon after it reaches 500rpm engine light comes on and it runs rough. i've replaced plugs, wires, fuel filter. and a lot of others. it does it every time its not like a once in a awhile its every time. and driving it sputters about stalls but doesn't.

My car has 179000 miles.
My car has an automatic transmission.

Hey there. This is a common sign of a 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. 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. As you let off the gas, the RPM slowly returns to the normal idling speed. This is all done by the idle air control valve. When the engine RPM drops below the normal range of 750-800 RPM (for most cars), this may indicate a dirty or faulty idle air control valve. In cases where this valve is dirty or failing, your vehicle will stall instead of slowing to an idle after the release of the throttle. If you would like to have this taken care of, a certified professional, like one from YourMechanic, can come to your car’s location to replace the idle 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・Fair and transparent pricing

Get a quote

What others are asking

Q: Need to replace camshaft position acuator

Without additional info as to your engine type, this cannot be diagnosed properly. The camshaft position sensor on "most" vehicles is located near or around the camshaft/valve cover. If you run into any issues I would recommend having an expert...

Q: HVAC control panel

You may just have a bad blower motor or blower resistor for the front A/C system. The blower would need to be checked to see if it is getting power to the motor from the blower switch controls. If you...

Q: Car is jerking for a while and then runs fine

The TCC is the torque convertor clutch solenoid inside the transmission. To get it replaced you would need to have the pan removed and the TCC solenoid tested and replaced. If all your drive issues start to happen after...

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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
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...