Q: engine idles rough and slow after replacing the battery

asked by on

After replacing the battery, the engine idles very rough and will die with the air on.

My car has 225000 miles.
My car has an automatic transmission.

You will need to re-learn the idle for the vehicle to get it to idle high enough. You should first clean the throttle plates and throttle body and idle control valve. When you disconnected the battery, the idle control was reset to factory and will idle differently unless you relearn the idle again.

After cleaning the parts out, then start and run the engine at 1500 rpms to warn engine for a few minutes, and then let the car idle with all accessories off for two minutes. Put the vehicle in drive and let it idle for two minutes then turn on A/C on medium blower speed, and then let it idle in gear for two minutes. Put it back in park and idle for two minutes with the A/C on. Then road test for about 5 miles in stop-and-go traffic. This should fix the idling issues.

If you need help with all of this, consider having a certified technician from YourMechanic come to your car’s location to diagnose the rough idle and perform any needed tasks to have this resolved.

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. engine idles rough and slow after replacing the battery

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: Q: Car stuck in park.

Hi, Since you have already been working on the problem you would have to have a certified technician come and diagnose the problem you are having. The gauges jumping around either is a low battery or you have a wiring...

Q: Q: Shifter will not go into gear

Hi there. This can be an issue with your shift linkage being loose or not correctly adjusted. It also can be something malfunctioning inside of your transmission. I suggest having a certified mechanic or transmission shop take a closer look...

Q: Where is the grinding noise coming from?

Hello. If this only occurs in one direction, then I usually check inside of the fender well for shinny spots. If there are any shinny areas, that would mean that there is something rubbing, such as the tire rubbing. If...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.