Electrical Alternator Causing Power Loss

Hi all!

Something recently happened to my '07 and I thought I would share the details in the hopes it might benefit someone else...

A little over a month ago I began noticing a substantial power loss in my Stang. It was as if someone had thrown a few hundred pounds of weight in the trunk...she was just plain sluggish.

Over the past few weeks I've tried everything from plugs, a compression check, fuel injector cleaning, throttle body cleaning, oil change, new gas/filter and oil and air filter..all to no avail. Well, last weekend she left me stranded about 40 miles from home after a night out with friends. She was acting fine with all guages reading normal and no idiot lights or engine codes being thrown. Out of nowhere the ABS idiot light came on..followed by every other idiot light in an almost mocking manner. Less than a minute later the headlights go out(not fun at 1AM), so I pull into the next hotel parking lot where she proceeds to die on me. She would not even turn over again..the battery was completely drained.

The next morning I had a friend bring my tool box to the hotel(had to stay the night) and I decided to change out the alternator. I found a replacement unit at a local Autozone a couple of blocks away and it took me about 90 minutes to remove and replace. After a few minutes on jumper cable life support she started right up. As I drove her around the block I noticed all of that lost power I had been missing had been restored as she growled, barked and lurched sideways with the slightest of throttle input. It was like she had come back to life.

I took the bad alternator to a local shop to have it tested in an effort to find out what went wrong. Amazingly, the alternator was maintaining 13.5 volts at idle, but current throughput was dropping to -zero- at anything above 1800-200 rpm's. According to the tech at the alternator shop, between the PCM, fuel pump system, coil-on-plug system and other sensors, the charging system in Stangs is heavily tasked...especially at higher rpm's, and as the alternator reaches the end of its life, horsepower can be reduced as voltage/amperage drop. It was explained to me that the computer does not like to see less that 12-13 volts, and performance will start to be affected when voltage dips below a nominal level.

The weirdest part in all of this was that I -never once- received any warning in the form of a charging sytem idiot light..no flashing..nothing. Nothing to indicate the alternator was about to fail. This occured with a little over 78k miles on the odometer.
 
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