Q: Irregular power and idle

asked by on

My battery light first started popping on after the alternator was replaced in about July/august. At first there was no really symptoms other than that. The battery was checked numerous times and it checked out fine. After a few months I could start to hear the idle speed change when the battery light came on. I also started to notice the dash lights and headlights "surging" up and down while driving and idling. I've posed the question to numerous car people and can't get a definitive answer. The most common answer however is my idle air control is going bad. I just want to know for sure so I know what to do next. Thank you. Kendra.

My car has 97000 miles.
My car has an automatic transmission.

Hi Kendra, Your idle air control valve as you may know monitors air intake as it enters the engine while the computer uses this info to make adjustments to the air/fuel ratio. When this is dirty or not working properly, this may cause the idle to fluctuate as you have described. The surge in the lights going up and down may suggest that you may have a faulty alternator or voltage regulator. The alternator charges the battery as the engine turns the alternator, so it may be possible that the struggling idle may impact the charging system as well causing a drop in the system voltage which results in the lights surging. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your car.

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. Irregular power and idle

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: 2014 Ford Focus Blower Resistor Location

If you have Electronic Manual Temperature Control (EMTC), the blower motor resistor block is accessed by removing the accelerator pedal. Once the pedal is removed you will see the wiring harness to the block and the single retaining screw that...

Q: Q: Car stalls at a low speed

Hello. You can try and clean the IAC valve, but if it is bad, it will need replacement. Cleaning the IAC valve would only be a temporary fix. The IAC valve is usually attached to the throttle body, and can...

Q: Rough Idle in park and neutral runs smooth in gear

You will need to have the engine checked to see if you have codes to assist with diagnosis before looking at getting the ECM reprogrammed for the rough idle at a dealer. I would suggest having a certified technician diagnose...

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...
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.