jlopez07

Okay so long story short, battery kept dying, wouldnt hold charge. Replaced battery, same thing happened. A trip to O'Reilly, and it was the alternator. $267 later, I swapped them, no issue. Started up fine, kinda lagged a bit like it wanted to die, but charged up amd was okay. Drove back to O'Reilly to take my old one back. When reversing in the parking lot, my car was sputtering and hesitant as I reversed and then stopped as I was going forward. Whenever I turn the car on, it acts like a low battery, like it doesnt have enough power. It starts up, then drones down and then picks back up. Any ideas? Battery is new and so is the alternator as of today.

Stangbass

Did you charge your battery after replacing the alternator. If not that would be my first step. The alternator isn't really meant to charge a dead battery. Your charging system trying to charge up a dead battery while running electrical accessories on your vehicle could cause the problems your experiencing.

jlopez07

Update: car ran fine today. Only thing ive noticed is the shuddering when I got to a stop now.

2005Stang

I just put a new battery in the 2005 Mustang and I have noticed the the heater fan seems to go to a lower rpm. I took her to an auto parts place that tested the alternator and the readings were 14.66 no load and 14.63 volts with a load, they told me it was putting out too much voltage, I am going to get another check my next day off just was wondering if that was true or are they just trying to send me a 200+ alternator.

Nuke

When charging, the alternator should be operating at about 13.4-13.6 volts. You should be able to easily confirm that with any run-of-the-mill volt meter. I'd say the regulator internal to the alternator is bad.

The charging systems in these S197's are chronically mediocre. Buy a PA Performance alternator and be done with the OE MotorCrap units.

2005Stang

Thanks Nuke, I will look into it. Mabe the 200 amp one..

flyhigh@mach1

Let us know how the alternator works out. Was it a brand new one or a rebuilt? I heard the Motorcraft alternators are crap but also heard that the electronics inside factory alternators work best with the computer in our cars. Who knows?

flyhigh@mach1

Unless you have a bigger sound system or more lights, the stock amp output is fine. If you do have more draw on alternator that came stock, then you can upgrade to higher amps, but you will have to change out battery to alternator wires because they cant handle 200 amps safely. I believe PA Perf. offers those wires too.

jlopez07

It was a brand new motorcraft alternator. Car is running fine. I think I was just paranoid and looking for any little thing wrong. I have notice my engine seems to shudder though when Im at a red light

Nuke

That could be the TB needing a good cleaning and/or the fuel system needs a dose or 2 of SeaFoam or Techron and/or your fuel filter needs replaced.