95 5.7 Formula - Electrical / Charging Issues

Hey everybody! Not many posts but i'm an avid reader. Was just tinkering around cleaning up the firebird for spring (she's couped up all winter) and figured i'd get back to troubleshooting the electrical issues it was having last fall before i put her away.

Basically -> these are the symptoms i simply haven't been able to get rid of. They've happened since i purchased the car used about 3k miles ago.

At cold start, engine fires great and voltage maintains at 13v (guage). Windows open fine, lights okay - car is just peachy.

Once the engine is warm, voltage falls with decelleration and at idle. At idle, it sometimes goes all the way down to 10.5-11 volts and it has shut the whole carr off before. Yikes.
I do notice that the IDLE is low once car warms up.. just about ~550 rpm? One said it was cpu controlled all that so idle shouldnt matter. Anyhow.

I replaced the alternator with a bosch premium, battery with the best DIEHARD and had a professional look over the cables to the charging system to verify they were AOK. He replaced the connector terminal which touches the alternator.

When the voltage drops, the oil pressure guage seems to drop parallel with the voltage. They move at the same time upwards and downwards (as they should, just not so severely) with accelleration.

Is this common? After driving my car with the volt guage flopping for about a week or so, battery starts to become fatigued and it gets worse.

I just tested the battery with a nice load tester and it checks great. Its been on a maintainer all winter.

A neighbor thought my abs system was draining power, as ABS light would come on and the relay seemed bad. Replaced the relay as well as the wheel hub (speed sensor) on right wheel. Fixed abs but power problem still there.

Could it be something so simple as the thing idles too low? at about 700 rpm in park the voltage guage (and Oil pressure) go to straight vertical perfectness and when i let off the gas they fall.

What the heck is wrong with my bird?

maaybe your maintainer's burning up your new alternator.. thats what I'd check into.
You engine all dirty/grimy?
Dirty grimy connections can cause power drops, hot spots/shorts.
Sure as heck arnt fun runing down either. :nono:

Also check you starter wires and make sure they are tight and not any worn through.

Good Hunting superducky55!

Hey there! Thanks for the reply! :)
Maintainer is setup independent of car.. ie: disconnected the battery from the car altogether
My engine bay is generally damn clean, at least on top :D but i've checked most the connections i could. I replaced to starter when i first got it as they said it was going bad, connection looked fine then.

I suppose it just has to be a short somewhere.. right? How come the voltage is high when she first turns on? I'm good for regular mechanical workings but this stuff is getting above my head! :) Thanks again

bump!

Did you check the harness connect of the alternator. If the pins in the alternator are not making good contact with the harness the voltage regulator may not be kicking the alternator into duty. If all else falls you could always get a alternator overdirve pulley. I got one for my car but I had a amp that was draining my battery at idle.

voltage regulator? sounds like it to me, if theres no short, the belts are fine, the alternator works, the only thing between the battery and alternator is the voltage regulator!