Stalling after starting, just installed new alternator

[robbieas]

I just put a new alternator on my 2005 Explorer, it was a remanufacturered one from Autozone. Now when I start the car, it wants to stall right after cranking. It cranks fine – there is no lack of power and it cranks up just as smoothly as ever. But as soon as the starter disengages, the RPM drop to 400-500 for a second, causing it to want to stall out. The colder it is the more likely it seems to want to stall. If it doesn’t stall out, it runs a little rough for 5 seconds or so, then everything it perfectly fine and it purrs like a kitten.

The problem didn’t start until I put the new alternator on, and I didn’t do any other work on the car around this time. The first one from Autozone actually died after about 3 days, so I had them give me a new one which charges fine now – but both of them had this starting issue that the original alternator didn’t have.

I guess I’d point to the Autozone cheap alternator as the culprit, but how is it an alternator is causing this problem? It doesn’t seem to make sense to me that an alternator could cause a rough start like this. Anyone have any thoughts or experiences on this? Thanks in advance for the support!

 

[D Hook]

Assuming you disconnected the battery, you might have to wait and let the vehicle "relearn" it's settings.

It took mine about 40 miles and several on/off cycles of normal driving to get it back to what it was before the battery was disconnected.

 

[Sedition]

Did you plug the regulator back in aswell? or just the B+ terminal?

 

[jstorm001]

Replace my alternator last week with the gold duralast alternator the computer does need to relearn goes back to factory default settings so it will act funny or shift weird like said above my 02 explorer ran rough also wanted go stall when idle or at a stop cleaned my throttle body & MAF sensor it runs so smooth now like new getting better mpg also try it out on yours also.

 

[mdisalvo]

I just went through a very similar thing last night after replacing my alternator. I figured out it was a dirty MAF sensor causing the rough idle. What I did was unplugged the MAF sensor, started the car (it then idled smooth) and waited a couple seconds then plugged the MAF sensor back in. I think this helped blow off some of the dirt that may have become attached to the MAF sensor when I was replacing the alternator and bumping the air box/MAF sensor/throttle body area. Try it out and let us know if it works.

 

[robbieas]

I unplugged the battery, waited ~60 seconds, plugged it back in. Drove ~75 miles with multiple stops along the way, and it may be a little better, but still not perfect. I'll give cleaning the MAF sensor and throttle body a shot... can't hurt.

Sedition - I'm not sure what the regulator or B+ terminal refer to. When I unplugged the battery, I just disconnected the negative terminal.

Thanks to all of you for your helpful advice, great helpful forum here!

 

[Sedition]

On the Alternator the plastic clip type plug is for the regulator (regulates voltage according to electrical load)

The B+ terminal is the metal stud connection on the alternator. (This connects to the Positive terminal on battery through the wiring harness)

 

[premeirmerc]

Replace my alternator last week with the gold duralast alternator the computer does need to relearn goes back to factory default settings so it will act funny or shift weird like said above my 02 explorer ran rough also wanted go stall when idle or at a stop cleaned my throttle body & MAF sensor it runs so smooth now like new getting better mpg also try it out on yours also.

man werid i also replaced mine last week and the spark plugs and wires and it wantss to cut out also and some times does on start up.. but my throttle body looked really clean .. only thing i could see that looked werird was a plastic line like a vacuum line extended from the fire wall , one going to a harness behind the manifold and one going to the intake tube area but its broken off like it got pulled off ... would this cause the rough idle as well or could it be what you guys did by cleaning the maf sensor?

plus what might these lines be/ go to, im a honda guy first times working on fords

 

[robbieas]

I finally got around to cleaning the MAF sensor. I disconnected the battery, removed the sensor, and cleaned it with MAF cleaner (CRC from Autozone, $7.49). Reinstalled and reconnected the battery.

It appears to have fixed my issues. I ran a few errands yesterday and it was starting better each time. This morning on a very cold morning start it fired right up. My understanding is that the computer needs a little time to readjust all of it's settings, and it appears to be getting better.

Hope this thread is useful to others with similar issues. Good luck!

 

[mdisalvo]

Awesome! I had a feeling that would help, it certainly solved my issue, which was identical. I might remove the throttle body and clean that up next just to see what difference it makes.

 

[matt0248]

Remember that on '04 and newer the Throttle body is electronically controlled. There is an idle relearn precedure that should be done. I have heard that it is in the owners manual. This need to be done anytime the battery is disconnected. MAke sure the t-body is clean too as this can affect the t-body operation and idle speed. The Electronic T-Bodies do not use an Idle Control Valve to control idle speed.