svp928

My car idles now at about 750 rpm. It was "hunting" between 800-1100 before the alt change. I actually left the stock GM pulley on mine to see if it had a problem at idle- at 600 rpm, it doesn't put out enough charge, but at 750 its fine. The GM pulley is larger than the stock one, so I was surprised it worked.

All the above advice is a good idea regardless of which alt you have...at 130k miles, mine was no longer up to the task.

dcrasta

Makes sense since all the sensors require a stable baseline voltage or the readings will be off.

Dannyfumi

I had the same symptoms you described, chased down and checked all the stuff people are recommending. It turned out to be the alternator.

Good Luck

svp928

Actually ,the nose bearing in my alt was going bad, and the growl it made with the lopey idle sounded like the car was supercharged........too bad it didn't run that way
Now its smooth and boring.....

Dictys

Well I replaced the battery and cleaned the grounds and at now I get 12.6v at the jump point with everything off and 13.8v with the engine and fans running.

It didn't idle rough this morning with everything on, so I'm just going to monitor it and the replace the alternator and belt a little later.

Thanks for everyones help.