Q: Idle fluctuates and then stalls.

asked by on March 02, 2017

i have a 2011 mitsubishi lancer and it shut off while i was at a red light. i put the car in park and turned the key to turn it off, then turned it back on. it started fine and was running fine. none of the lights are on on the dashboard. what could this be?

My car has 175000 miles.
My car has an automatic transmission.

What you are describing sounds like a dirty or 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 at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about 800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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

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

i have a 03 Mitsubishi galant and my service engine soon light came on. should i get an oil change?

Hi Victoria. Thanks for contacting us today. If the engine is stalling occasionally, it's likely due to a fuel system component failure, such as a mass air flow sensor or other fuel system component. The warning light or service engine...

Gas pedal not going down when pressed.

The throttle pedal may be blocked by your carpet. Check the pedal to make sure it is not being blocked. The pedal operates a cable and then to the throttle body assembly. Each of these would need to be checked...

broken themostat, broken fan blower

Hey there. These issues may be related or separate problems. If replacing the thermostat provided heat, it was most likely stuck closed and not allowing coolant to flow to the heater core. The blower fan is a completely different circuit....

Related articles

A Buyer’s Guide to the 2012 Mitsubishi Eclipse Spyder
In In 2012 Mitsubishi says sayonara to the 22-year run of the sporty little Eclipse, and with it, the Spyder convertible. This sleek, stylish soft-top has enjoyed many years of popularity as a fairly affordable option for those with a...
A Buyer’s Guide to the 2011 Cadillac STS
Big, Big, bold and beautiful, the 2011 Cadillac STS is a full-size, four-door sedan that promises more than ample room for the entire family, as well as the power and performance you expect from the automaker. 2011 marked the final...
A Buyer’s Guide to the 2011 Ford Ranger
The The 2011 Ford Ranger offers affordable pricing with excellent styling. It is a compact pickup that is both inexpensive to operate and own. The vehicle is capable of going off-road while still being able to tow 1,600 to 3,100...