I have an 89 IROC with a 305 tpi motor. When I put my foot all the way down to the floor, the voltage gauge drops well below 13 volts and continues to drop until i get back out of the gas. When I get back out of the gas, the volt gauge goes back to 13 volts. The alternator is practically brand new and the battery is in good condition also. One other thing, I just installed two 10 inch subs with an amp. The problem started about a week after installation. Could this cause the problem? I'm lost???

 

Can somebody please help me out here...

 

sounds like maybe a short to ground or something, I would suspect the stereo system since it happened not too long after you put it in....but don't rule out other stuff as well, still could be a bad alternator even though it's new, maybe not producing at higher rpm

 

Thank you for the reply. I think i figured it out today. The positive connection on the battery, that goes from the battery to the amp seemed to not be making good connection. I changed the terminal and it seemed to work so far. Ill see what happens.

 

yep, that very well could be your issue...good catch.