BigP

Ok everyone, got a 98 T/A with an Optima red top. I noticed that when i first start the car, the voltage gauge reads a tick over 14, which is ok. After a few minutes, it drops down to about 13.5-13.7 which is still acceptable. Once the car is fully warmed up, the voltage drops way down, probably 12.9 or so. I have checked the battery static voltage, it is 12.5 so that's good. When the A/C is turned on the voltage gauge reads just at the end of the yellow caution range. If i turn on either the turn signal or wipers, i can phsyically watch my voltage gauge jump back and forth when they cycle. I'm not sure what the problem is. The alternator is a brand new GM unit, but it still does it. But not while driving though, only sitting at idle like at a light. When I come to the light and sit, the voltage will drop down, and then the engine feels like it wants to stall, all the lights dim a little, and i press the gas to get it back online. All my connections are tight at the battery and alternator. It almost seems to me like it has something to do with a voltage regualtor but I know that it is internal of the alternator. You guys have any suggestions on what it might be? Thanks in advance for any help!!

WhiteRhino

iTrader: (6)

It might be possible you got a bad altenator. Also make sure that the little wire coming out of the top of the altenator is hooked up. Or that it's not broke.

jkichline

iTrader: (1)

Do you have an underdrive pully system? That behavior would be common if your alternator is not spinning very fast. That makes sense that it happens at idle and not while driving. Also make sure your belt has a good amount of tension on it and is spinning your alt pully like it should.
If you have to give it gas to keep it running, maybe you have another issue causing a low idle. Maybe dirty MAF or another sensor going bad or something. Does your CEL ever come on? Is your car automatic? Will the same symtom happen in neutral or park?

BigP

No underdrive pulley system, everthing is factory. I can double check the tension of the belt to make sure that isn't the problem, but I have checked it before and it seemed to be ok. Yes I do have a check engine light, but it is a code for the O2 sensors due to using the long tube headers and aftermarket cats. A dirty MAF might be another possibility seeing as how it has been descreened. The car is an automatic with a TCI Street Fighter 3000 stall converter, shift kit and corvette 1 and 2 shift solenoids. It will only happen when the vehicle is in driving gear ie. drive or reverse. If it starts to act up in drive or reverse, i can put it in neutral and the rpms will increase slightly and the voltage will go back up to the 13.4-13.5

joecar

The voltage regulator in your [new] alternator may be bad.

kapedogg

iTrader: (5)

Did you ever figure this out. I seem to have the same problem. Thought it was the battery after draining it a couple/few times, just put in an optima red top and have the same symptoms.

staringback05

iTrader: (8)

people are starting to learn about that little sensor....

check that because it effects the charging of the battery.....also when you turn the AC on, for it to fall is normal...mine goes from around 13.5 to 12.8....run a volt meter on the wires and see if there carrying the right load...