Skip the auto shop - Our mechanics make house calls

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.

A: You will need to re-learn the idle for the ...

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?

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: my car shaks after adding oil

Hi there: It's highly unlikely that the addition of oil or gasoline triggered the engine shaking situation you're experiencing now; unless he mistakenly added diesel fuel to a gasoline powered engine. It might be a good idea to have a...

Q: Car won't start, turns over and lights come on

Hi There, It sounds like you may have a faulty connection to the starter or possibly a failing starter relay. The starter relay directs power from the battery to the starter solenoid which then engages the starter when you turn...

Q: Vehicle failed compliance check.

Hello you have two concerns going on here. Lets start wit the P0410 for the secondary air injection. Start by checking the fuses. You should hear the pump come on within the first few minutes of start up. If the...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control 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...