Unstable/Low Voltage?

[sandersb]

I have a redtop SR20DET in a 92 fastback. I've been having a problem where I have a very low voltage reading at the turbo timer (around 11v), and the voltage won't stabilize. It flickers around 11 for the most part. I had a crappy battery, so I put in a brand new fully charged one, and still could not get more than 11.9v at the timer. to add to that, every time I rev the engine, the voltage drops substantially. Also, there's a very loud whining sometimes coming from the front of the engine. I'm thinking the alternator's going, but I'm getting this low reading even when the motor's off.What is going on?

I searched and could not find a problem/solution similar to mine.

Thanks

[vocationalzero]

Your alternator is going out. The car is old enough to where you SHOULD be able to get away with disconnecting the battery cable while the car is running. If it dies then the alternator is done. (I only say SHOULd cause I've got a 92 and it works)

[positron1]

I agree, I just had a problem similiar to that. I replaced the alternator and the car fires up so quickly and runs like a top. Now the only time I notice a change in voltage is when my fans come on.

[dc1984]

i think the best way to check tha alternator would be to use a voltometer. ive read that disconnecting the battery is an unsafe way to test the alternator as the battery acts as a stabilizer for the electricity generated by the alternator so disconecting it can result in spikes which might cause some electrical damage. not telling u not to do it cause i know ive done it before but after reading this, ive always thought it to just be safer then sorry.dont know if all this is true but it sounds like it could be.

i know that some battery shops will do a test for free to tell u if it is ur battery or alternator having trouble and they do this with a voltometer. look around ur local area for a place that will do it.

[sandersb]

I already tried pulling the posi cable off the battery, all that happened was the rpm dropped for a second, but then went back up and was fine. I'm getting the alternator rebuilt, but even if it was the alternator, I should get more than 11 volts with the motor not running. I'm thinking a bad ground, or a loose circuit causing a draw?

[GoTRicEo0]

alternator pumps out more voltage when the engine is underload. Don't be too quick to jump the gun and start dishing out money. Check wires for corrosion and junk. Check where all the hot wires meet. (Around the battery terminals, fuse box, hot wires with screws, and so on)

Getting a battery thats oversized for the car would have that effect also. Aftermarket stereos/amps, if you got em.. thats the 2nd place I'll check.

~Edit, har har har... after reading that your reading voltage from the turbo timer. All that wire is gonna have resistance. There's the drop. Check with a volt meter to be 100% sure.

[sandersb]

I pulled the alternator and tested it; it's still good.BUT: I pulled the posi wire off the alternator and it pretty much crumbled and cracked in my hand.I think I found the problem.

Thanks for the help guys! I'll post the result when I put the alternator back in.

[virus77]

yeah I was gonna say its probably a corroded wire really close to the positive terminal, happens to these cars allllll the time.