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View Full Version : Possible problem w/ Alternator, please help


Autotechnica
03-31-2003, 09:40 PM
Hey guys,

I've had a problem with my car ever since I got it about a year ago ('94, not my '92). I just replaced the battery about 3 months ago so I know it's not that. But I noticed my idle is very unstable. Each time I turn on the fan, defogger, power windows, etc. the Idle will fluctuate and become very unstable. Each time I rev it up it seems like it wants to stall. However, when I don't use any power'd anythings the idle is just fine, smooth as ever. Does this sound like an Alternator problem? I know the best way to check is to start the car and unplug the battery then see if it dies, but I dont' want to reset a lot of the electronics in my car.

How much does a rebuilt alternator run? Places? Thanks!

Bryan

WASABI
03-31-2003, 09:46 PM
Do you know how to check alternator with a volt meter? Like you know how it should be around 14.7volts or higher (but not over 15V) when the engine is running. You may want to try it. The alternator might be outputting less than it should.

I know a couple of place here in mississauga. Yellow pages?

Autotechnica
03-31-2003, 09:51 PM
Originally posted by WASABI
Do you know how to check alternator with a volt meter? Like you know how it should be around 14.7volts or higher (but not over 15V) when the engine is running. You may want to try it. The alternator might be outputting less than it should.

I know a couple of place here in mississauga. Yellow pages?

I thought 14.7 was the normal battery level? How do I check the alternator voltage? Is it the positive terminal at the front of the engine bay at the back?

Thanks,

Bry

WASABI
03-31-2003, 10:00 PM
Mid 12 volts is usually the normal battery level, when you start the car it should jump to around 14.7V (alternator running).

You can do it at either end (trunk or engine compartment). Put the volt meter across the battery (just like when you're measure it's voltage), start the car and watch the voltage go up. OR if you're by yourself, measure the voltage of battery first, then start the car, and measure the voltage again, there should be at least 2volts difference (normal).

Furious
03-31-2003, 11:45 PM
hey Bryan... are you sure its not your idle control valve? my car has the same flux as yours does and i know that my alternator is ok. however i dont seem to wanna stall out. but i do get that idle bounce and some times pretty bad.

Autotechnica
04-01-2003, 12:17 AM
Originally posted by Furious325is
hey Bryan... are you sure its not your idle control valve? my car has the same flux as yours does and i know that my alternator is ok. however i dont seem to wanna stall out. but i do get that idle bounce and some times pretty bad.

This could be possible. However, the idle is only erratic when I use anything which uses up battery power such as; power mirrors, fan, air conditioning, rear window defogger, etc. Other times the idle is usually quite smooth.

Anyways, where the idle control valve located? Can it be adjusted or it simply needs to be reaplced?

Thanks,

Bryan

M52_Alpina
04-01-2003, 04:37 AM
it could be the throttle position sensor. Check the resistance of the tps. Bad tps will cause erractic idle when the A/C is turned on.

Furious
04-01-2003, 11:41 AM
Originally posted by Autotechnica
This could be possible. However, the idle is only erratic when I use anything which uses up battery power such as; power mirrors, fan, air conditioning, rear window defogger, etc. Other times the idle is usually quite smooth.

Anyways, where the idle control valve located? Can it be adjusted or it simply needs to be reaplced?

Thanks,

Bryan


when i get home i will get you the DIY to cleaning it. i dont think it needs to be replaced but cleaning it will help (i hope) rectify the problem .

WASABI
04-01-2003, 08:49 PM
Did you do the alternator test? What readings were you getting?

koncise
04-02-2003, 01:56 AM
Originally posted by Autotechnica
I know the best way to check is to start the car and unplug the battery then see if it dies, but I dont' want to reset a lot of the electronics in my car.

How much does a rebuilt alternator run? Places? Thanks!

Bryan

I wouldn't do that test by disconnecting the battety. I did it and thankfully nothing happened, but I told my bmw mechanic and he said it can really f*ck the computer or something in our cars. I wasn't really listening :) (he was talking to my dad).. but I think he said whatever it f*cks up is like a $1000 repair.

Anyway, I paid $450 for my rebuilt alternator...labour included. Mine was in really bad shape.

Hope this helps.

Autotechnica
04-02-2003, 02:42 AM
Originally posted by koncise
I wouldn't do that test by disconnecting the battety. I did it and thankfully nothing happened, but I told my bmw mechanic and he said it can really f*ck the computer or something in our cars. I wasn't really listening :) (he was talking to my dad).. but I think he said whatever it f*cks up is like a $1000 repair.

Anyway, I paid $450 for my rebuilt alternator...labour included. Mine was in really bad shape.

Hope this helps.

$450?! Man, I'm looking to spend around $100 and that's what most shops quoted me for rebuilt alternator. I can install it myself though.

I don't see why it should short anything out unless you purposely shorted out the ground. Doesn't make sense? :confused:

Bry

mpower1226
04-03-2003, 04:40 AM
450 dont make sense. You could bring your bad alternator to a rebuilt shop. They exchange to a rebuilt one instantly. It costs around 100 dollar to 120. Its an half to one hour job. It should run you about 150~160 with labour.

koncise
04-03-2003, 01:56 PM
Originally posted by mpower1226
450 dont make sense. You could bring your bad alternator to a rebuilt shop. They exchange to a rebuilt one instantly. It costs around 100 dollar to 120. Its an half to one hour job. It should run you about 150~160 with labour.

Maybe there was other work done too. I wasn't there the entire time, my dad took care of it more than me.