Skip the auto shop - Our mechanics make house calls

Q: Rough idle and flickering lights.

asked by on

What is causing my car to run rough while in idle and my lights are flickering. Any suggestions? It is a 5 speed with quite a bit of miles.

This may be related to a dirty or failing idle air control valve. The idle air control valve reads 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 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. The lower idle may also cause the lights to dim in the event that the battery may be weak. As the RPM’s dip, the production of the alternator dos as well, causing the charging amperage to the battery to drop. I would recommend having an expert from YourMechanic come to your location to diagnose and repair 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!

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: What is the break-in period and how long does it last?

If you’ve heard of the “break-in” period on a new car, but dismissed it as a myth – it’s not. Honda recommends a break-in period of 600 miles. But what does that mean? It’s actually not that complicated. Here are...

Q: Buying Advice on 1999 Toyota Camry, LE Used Miles:233,000...Should i buy it?

I would suggest checking the Kelly Blue Book website with specifics related to your zip code as market prices of cars vary by zip code. This will give you a baseline for determining whether or not the car is within...

Q: Poor idle car keeps shutting off

Sound like your fuel pump stopped or something else is causing the no start like timing belt? Have the vehicle checked and diagnosed by a mechanic like one from YourMechanic.com to find the reason of the no start.

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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.