Rep Power: 687

Okay, so I had the issue with the voltage of my car going down at stop lights. It would linger close to 8 amps and slowly go up and down between 9 and 10 amps I guess. Never stayed up near 13amps. If I accelerate, it goes back to normal, near 15 amps or so. I changed the alternator and all, and it's still doing it now. Is the battery maybe the issue? I changed a few months back thinking it was it, and now I changed the alternator and still the same. Should I go back to Sears and get the battery replaced since I put the new alternator in? Anything else it could be here?

 
Rep Power: 1069

have the charging system tested, but are you actually measuring amps or volts? If amps your way low (should be near 90) volts is low at idle, and if you have underdrive pulleys could cause that (hence they lower performance since your car needs 14 volts to run correctly) a bad battery can cause that, but so can a short in the system, and a bad regulator (if it's a rebuilt alternator it could be bad, as they only replace what was the original cause of replacement)

 
Rep Power: 687

Where can I go to get the charging system tested? What type of shop?

I'm measuring what I see in the dash. I'm not sure if it's in volts or amps... sorry...

The alternator I made sure I bought it new and not rebuilt. I prefer new stuff. As for the regulator, where is the regulator and how do I check it?

A member on MFBA said maybe the underdrive pulley also maybe. Do you know how to check if it is the cause?

 
Rep Power: 0

could be a loose ground brother

most parts stores can check ure batt n alternator

do u have underdrive pullys?

 
Rep Power: 687

It's a pain to take out that dang alternator. They can't check it with it on right?

And I think I have an underdrive pulley...

 
Rep Power: 1069

most parts stores can test the system in the parking lot, if you have an underdrive pulley get a stock set it may fix it (if you didn't change the one on the new alternator, and have an underdrive one on the balancer you will have many issues)

 
Rep Power: 829

I had somewhat similar issues with my car when I had the underdriven crank pulley. It wasn't quite as bad you have- but I would notice the volts would drop slightly at idle, but once it got past 1500 rpms it would be fine.

Like others have said, take it an auto parts and have them give it a quick check..

 
Rep Power: 687

Well, went to Outlaw Motorsports on Sunday. It's confirmed that I have an aftermarket underdrive pulley. Need to find a stocker and see if that will fix it. It happens when my day time driving lights turn on. Runs fine without them, but happens when it gets dark. Go figure..

 
Rep Power: 0

when it gets dark and u turn on all ure neons on eh? hahaha

 
Rep Power: 1069

lights draw a ton of current, you are running at half voltage basically