Q: Car idling rough after replacing alternator
My car is idling very rough after replacing alternator
My car has 161000 miles.
My car has an automatic transmission.
After replacing the alternator, your vehicle’s ECM will need to go through a "relearning" process whereby it will take a day or two for it to relearn the computer’s parameters and adjust. If by replacing the alternator, the battery was also presumably dead at some point, this will cause the ECM to need to relearn some of the fuel injection memory related to programming, fuel curves, etc. When this happens, you will notice a bit of rough idling and potentially, loss of power until the ECM relearns all of this information.
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
What others are asking
Vibration in drivetrain
Hi there. This vibration could be caused by a number of things. However, the first place I would look is the driveshaft and u-joints. The driveshaft is used to transfer engine torque from the transmission output shaft to the rear...
Whats the cause of a whining tramsmission, blinking overdrive light, hesistant to shift properly?
As a rule, I NEVER change the transmission fluid on a vehicle with that high of a mileage unless it has replaced regularly throughout the life of the vehicle. Replacing fluid that is thick with new fluid can cause issues...
what causes transmission to not shift? 2001 Dodge Ram 1500
Hey there, thanks for writing in about your 2001 Dodge Ram 1500. This is a common issue on many automatic transmissions. There is a speed sensor (https://www.yourmechanic.com/services/speed-sensor-replacement) which is a magnetic coil that tells the vehicle's control module what the...
I replaced the camshaft position sensor and now my car stalls after 10 seconds.
Hi there. The crankshaft position sensor works in junction with the camshaft position sensor. Check the crankshaft position sensor and see if the wiring is loose or disconnected. Check the sensor for any voltage reference coming out of it when...
2007 Nissan Maxima - TPMS Light Warning Light
Hi Mike, As you know, your car has sensors at each of the four wheels that monitor the tire pressure at each tire. When these tire pressure sensors (https://www.yourmechanic.com/services/tire-pressure-sensor-replacement) fail, you may notice inaccurate readings as to your tire pressure....
Hesitation when accelerating
There are a number of things that may cause the car to hesitate (https://www.yourmechanic.com/services/engine-hesitates-during-acceleration-inspection) when accelerating such as low fuel pressure, a dirty or faulty mass air flow sensor, clogged or dirty fuel injectors, a faulty throttle position sensor or...
My car has a code P0342 replaced twice now won't start
You may need to check the wiring harness that runs to the camshaft position sensor (https://www.yourmechanic.com/services/camshaft-position-sensor-replacement) as it may be faulty or have a poor connection resulting in the sensor not providing an accurate signal to the computer, which would...
1991 Ford F-250 needs ignition switch reinstalled
Sounds like someone bypassed the factory ignition switch circuit. This indicates there was a problem with the circuit to begin with. The lock cylinder would need to be physically relocated to the steering column. Then, the ignition switch circuit would...
My car is making a whirling noice when pressing on gas pedal and when braking. It’s also making a popping noise after it parked
The origin of the noise on accelerating versus braking could be different (brakes can be the source of noise apart from, say, the engine). With regard to engine noise, does the noise occur when the car is parked as you...
Related articles
A Buyer’s Guide to the 2011 BMW X6 ActiveHybrid
This This “Sports Activity Vehicle” – a moniker bestowed by its maker – is one of those few cars that toes the line between SUV, hatchback sedan, and a just plain quirky car. Regardless of its true identity, however, the...
The Best Used Cars to Buy if You Live Close to the Ocean
If If you live close to the ocean, your vehicle is going to be far more vulnerable to rust than if you lived further inland. And the fact is, when it comes to resisting rust, not all vehicles are created...
Ten Sports Cars That Double as Good Daily Drivers
The best daily driver is a car that's reliable, usable, and still fun to drive. Popular daily sports cars include the BMW M3, Subaru WRX, and VW GTI.
Browse other content
Maintenance
Cities