Voltage irregularities

[eoseitz]

I have a 1990 Laser RS Turbo. I've notice lately my voltage is fluctuating. I have a voltage meter on my radar detector. I know, not real accurate, but its all I have right now.

So the voltage will drop down to around 11 volts. Sometimes even 10. Then jump to around 13.3. I've checked the tension on the alt belt. It seems fine. I've got a red top battery and a car audio battery. Even with the stereo system off the voltage will jump some. Not so bad though. And when the cooling fan kicks on the car will not want to stay running. It misses.

Could it be a bad alt? I had autozone test it and they said it was producing 67 amps. They said the alt in my car was a 70 amp. It should be a 90 amp in a turbo'd vehicle shouldn't it? How large of alts can you get for dsm's?

voltage up to 16 volts now. However, I do hear the belt making noises now. Not sure how the belt could be slipping yet its making more voltage. . Oh well. I guess I'll have to adjust the belt.

 

[DGajre777]

Your voltage regulator is not working. Get a new alternator or have your alternator rebuilt with a new voltage regulator before you end up frying things like the ECU.

 

[xxsupralvrxx]

yup sounds like your alternator time to get a rebuilt or new one. I had this happen on my 305 firebird but my alternator seized up soon after!(not sure how) I went to advanced auto an got a rebuilt one with a warrenty!

 

[4Motion4g63]

90amp is the biggest, get it from advanced auto part if there is one around you, it is a factory rebuilt.
To help the life of the alts you might buy a alt relocation kit from punishment racing but that only works if you deleted your ac...Heat from the manifold kills the alts over time..

You can also change our cars to a Saturn alt, but this will require a little modification to the block and alt...

 

[Defiant]

The noise probably isn't your belt:
http://www.dsmtuners.com/forums/pro...-just-time-pics-video.html?highlight=harmonic

And it sounds like your alternator is dying.

 

[1LE]

Sort of a thread hijack, but maybe it will help someone and maybe someone can help me...

My car was producing perfect voltage except when I would leave it idling in grid at autox events, at which point it would drop down to battery voltage. At that point, all the dash warning lights start a real faint glow (including the low voltage light). Simply opening the hood seemed to let enough heat out to correct the condition (within seconds of opening the hood, the voltage would start to slowly climb to normal).

I decided that I'm way overdue for an alternator anyways (original on a '95). Had it replaced. The new one works perfect in those conditions, but the following odd behaviour has begun:

- Since about a week after the install, on starting the car when it's warm, the car sits at battery voltage (11.8-12.0 on my AFC (on the interior wiring harness), 12.3-12.5 on the jumptronix (direct to battery)) for the first couple minutes (with the dash warning lights doing the barely noticable glowing thing), then suddenly jumps to charging voltage (if at idle, there's a pronounced quick rpm drop when it happens, like the alternator has suddenly placed load on the engine), and the warning lights all go completely off.

- Starting last night, all the dash warning lights (and I mean ALL, including "low coolant", etc) came on full brightness, shut off, came back on (repeat several times) while I was driving down the road. Each full brightness event was accompanied by higher than normal (but not what I would consider "too high") voltage (13.9 on AFC, versus the normal 13.1-13.3 during "full charged cruising" and 14.4 on the jumptronix, versus 13.6-13.8).

Did I have the bad luck to get a new alternator with a bad voltage regulator (happened twice in a row to a friend of mine), or does it sound like I have additional issues that suddenly decided to appear right after the alternator swap? The full bright warning lights are what have me concerned, haven't heard of that happening outside of ECU failures. Even the radio event reference below only resulted in medium brightness of all the warning lights (but completely destroyed the driveability/idle, which are fine in this case).

Full disclosure: This car has the unfortunate history of a small electrical fire (botched aftermarket radio install) and the loss of 2 grounds straps (which wreaked havoc with the ignition coils and power transistor) in it's history.