when all of my acessories are on(windsheild wiper, headlights- brights on, stereo, cooling fan, everything that can possibly be on) my volt meter drops down to 9-10 volts, the stereo(i have a pioneer premier 640) will even cut out if i crank it all of the way. is my altenator craping out? the more accessories i turn on the more the voltage drops. shouldnt the volt meter stay around 13-14 volts no matter what is turned on. i had some drive-ability issues last summer/fall. car would start to hesitate and run poorly. usually happened in the rain and i think it was because i had everything turned on. lights wipers stereo. is it worth buying an alternator, even though it might be a shot in the dark. i dont drive the car right now, streets are salt covered right now and i wont drive it until april, but i still want to figure out why the car had a "mind of its own" and decided to run funny. how sensitive are these cars to not having full voltage delivered to the computer and engine electronics. the battery would get charged and it would always start up, but i want to fix the erratic way my car would run sometimes. it would sputter, misfire, run like it was rich and/or igition was cutting out, and sometimes it would even backfire. once it was so bad it almost blew a hole in the muffler. i you pulled over to the side of the road, shut down the engine and let it set for a while it would run great again. i cant explain it and i spent alot of money and time over the summer and i couldnt figure it out.
Items replaced:
cooling fan motor
EGR valve
oxygen sensor
catalic converter checked for blockage
EGR vaccum switch checked
igition coil replaced
plugs, wires and cap replaced
cooling temp sensor replaced
fuel pressure regulator replaced
cooling fan replaced
fuel filter
all of the easy stuff was replaced. problem is very hard to diagnose because car doesnt do it all of the time, every time i pulled up to have somebody look at it car would run perfectly. its very annoying when it does act up. i want my car to run good 100% of the time. i didnt replace my alternator yet, i thought it could cause a problem. any advice? im going to be getting a 3" exuast system and im going to be spending about 1000 bucks so i need to ensure i dont distort and blow a hole in a new performance exhuast system.

 

The Alternator can only supply X amount of current, when the demand is more than it can deliver the Voltage will fall off. You can look for an Alternator capable of delivery more current or there are Auto Electric places that can get alternators with more capacity for you.

 

shouldnt the stock altenator be enough to supply current to stock electronics + an aftermarket pioneer stereo. no subs nothing exotic that would draw a significant current load beyond what the car has factory, could somebody have replaced the factory altenator with a weaker one? if its not the altenator what else could it be? the only thing i have found out of place it a connector underneath the car that isnt hooked up. i dangles and i have no clue where it goes. its a 2 pin connector. i looked everywhere for something that it might plug in to couldnt find anything. i looked at the tranmission and everything appears to be plugged in. i just had my car running i start it up weekly during the winter. it ran good, and i just want to make sure my car doesnt act up anymore, especially after i am going to spend alot of money on it in the spring.

 

I doubt your alternator is the original, I mean your the car is 18 years old. My voltmeter drops the same as yours but I don't have any other symptoms other than the meter reading low. The stock gauges are not all that accurate anyway. I'm not sure the car expects everything to be on at once, anyway. Sorry I can't be more help than that. I do know Manufacturers in general try to get away with the lowest BOM they to increase there bottom line. So I wouldn't expect the stock alternator to be anymore than just adequate for the job.

 

Your stereo cutting out indicates either a bad connection between starter and interior, or both alt and batt being bad. Since you have no trouble starting the car I suspect the alt and batt being ok, and that you have an intermittently bad connection somewhere. Start at the starter where power to the interior is picked off of the heavy battery wire. Visually and physically inspect connections, wires, and fuse links for corrosion and tightness, giving wires a good 5 lbs pull. If it looks bad, burnt, moves, or breaks then it's bad. Continue following this wire into the car, to the ignition switch and fuse box. If you don't find anything wrong I suggest you obtain an accurate voltmeter and some length of wire that you can temporarily hook up to different points in the wiring so that you can find out how much and where in the wiring the voltage drops when you're having trouble again in the spring.

 

my 89 is doing pretty much the same thing i start it up and have full alt power but after driving until it's warmed up and then the alt cuts out completely the check engine light flickers and nothing works. it's running but when you push the accelerator it spit and sputters then a min or two later it's fine. I've been messing with this for about a week now. I think I have it narrowed down though. my alt and batt are newer so I know that's not the prob my cables are newer also got replaced last year. I'm thinking it's the regulator/ fusible link looking thing on the alternator wire. the bad part is that part stores don't have listing and most dealership don't go back that far. and I haven't been able to find one piece of info on the internet I mean this is ridiculous.