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  #1  
Old 07-08-2012, 03:29 PM
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Alex-svx Alex-svx is offline
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Question Bad alternator cause other problems?

When i should start the car before the summer.
I have a little accident whit the jump start. And blow the fuse line and my ecu.

But this have been replaced and all work fine. But i have had some trouble whit the acceleration when i tur my stearing wheel. And the check engine light have came and go. I have read the ecu code it say both knok sensor have gone.

But i have find out that i have bougth wrong battery its smaller 45amp then the car needs and now i have replace this whit 60amp.
Afer the car wont start for me one morning.
I mean that the engine sound better whit this battry the fist test drive.

But this moring the car wont start again the starter just say clik so i think the alternator have gone.
But my qvestion is can the error message just bee to bad power on the car?

Can i just bye brushes on this alternator and it will wortk again?
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  #2  
Old 07-08-2012, 03:55 PM
Blacky Blacky is offline
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Re: Bad alternator cause other problems?

A bad alternator can cause a lot of problems. Get the car started by charging the battery or get a boost. The alternator should put out around 14.3 volts.
Both knock sensors being shot can affect the power of the engine because the timing won't advance as much to protect against pre-ignition/knock.
The battery should be around 600amp CCA if I remember correctly. Also if it goes dead overnight you may have a parasitic draw which is draining the battery while the engine is not running.

Last edited by Blacky; 07-08-2012 at 03:57 PM.
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  #3  
Old 07-08-2012, 05:05 PM
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david_12121 david_12121 is offline
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Re: Bad alternator cause other problems?

the car goes crazy with a bad alt but that's not the only problem in your case...check the voltage...mine shows more of a 14.6...down to 14 is fine too but anything lower is a bad/rippling alternator
you can fix it but it'll cost about half the price of a rebuilt one, IF you can find the parts, which I could not(few months ago)

I doubt that the acceleration problem is coming from the alt or the battery
get a few voltage samples and post 'em here...one off(discharged), one car on(jump it but be careful), one after you shut it off...that explains a lot
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  #4  
Old 07-09-2012, 05:30 AM
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Re: Bad alternator cause other problems?

The battery hold a few days its new.
But on my sterio i have a volt meter but this is not correct but this show
13.0V and 12,9 so i think the car not produce enough power.

I should recharge the batteri and test it. But i was curious if the knock sensor is broken or is it just the power. I have not have anny problems whit it in the winter when i have take it in and out the paint shop.

Is it some way to chek it or is it just to bye new one.
I must order from us here in Norway they shoul charge 336$ for just one.

I have find rebuild parts for the alt here
https://www.partswebsite.com/subarug...n=4&type=parts
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1998 Legacy BG 2.5L GX
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  #5  
Old 07-09-2012, 12:38 PM
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david_12121 david_12121 is offline
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Re: Bad alternator cause other problems?

try this:
jump start it, then when it is on, disconnect the battery
if it stays on, but with a low voltage(less than 14) it is the rectifier, which is $198 on that website
I bought this when mine went out...it's working and making 14.6
you can ask someone to buy it for ya and then ship it to you...it'll be much cheaper

as far as the knock goes, I don't think it's from the alt...mine didn't cause anything like that...I would replace the alternator(if it has a problem), then worry about the knock sensors
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  #6  
Old 07-09-2012, 03:57 PM
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svxcess svxcess is offline
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Re: Bad alternator cause other problems? LONG

Quote:
Originally Posted by david_12121 View Post
try this:
jump start it, then when it is on, disconnect the battery
DONT DO IT!!!

The battery is used as a large capacitor and thus smooths out the half-wave rectified output from the alternator. Disconnecting the battery while the engine is running will cause all systems in the car to be powered from an 'un-smoothed' power source, and could damage some, if not all, of your car's systems. It would also cause a huge momentary power spike, which could also damage systems.

These power spikes can also be generated when connecting / disconnecting jumper cables. I know of people who have destroyed their car's ECU's doing this. The best way to check your alternator is with a multimeter. With the engine at a fast idle (1500rpm or so) and with the lights switched on and on main beam (to load the alternator) you should get a reading across the battery terminals of 13.5 to 14.5 volts. A reading outside of this indicates an alternator problem. Similarly measure the AC voltage across the terminals. It should be less than 10VAC. Any voltage above this indicates that either the battery is failing to smooth the rectified output of the alternator (shorted battery plates usually), or the rectifying diode pack on the alternator is faulty.

As I said earlier, your battery does more than just yield electricity. It acts as a shock absorber. it also shorts AC, spikes and transients to ground. Removing the battery from the circuit allows those spikes and transients to travel around, endangering every semiconductor circuit in your car. The ECU, the speed sensitive steering, the memory seat adjustments, the cruise control, and even the car's stereo.

Even if your computers and stereo remain intact, in a great many cases removing the battery burns out the diodes in the alternator, necessitating a new alternator ( this has been confirmed many times by Christian at Maniac Electric Motors)If disconnecting the battery interferes with the voltage regulator's control voltage input, it's even possible for the alternator to put out hundreds of volts, frying everything.

Even the initial premise was wrong. If you disconnect the battery and the car conks out, you don't know if it conked out due to insufficient alternator current, or whether the resulting transients caused your ECU (the car's computer, which controls fuel mixture, timing, and much more) to spit out bad data, shutting down the car.

Using a multimeter is a good way to check your alternator. If you don't have one, here is a simple way to check it out, without any tools.

It'll help you to diagnose a BAD Alternator in a pinch. It's a fast test and more importantly an effective test to find out if the alternator is in fact bad. This test doesn't require any tools, such as a multimeter or anything else.

Also, you can avoid the most common mistake made when testing an alternator of disconnecting the negative terminal of the battery while the engine is running. Not to mention that this is a really, really bad way of checking for a bad alternator.

Here are the common symptoms of a BAD Alternator:

The vehicle does not start.

If you jump-start the vehicle and it runs, but after a few minutes or seconds after you disconnected the jumper cables from your vehicle's battery, the vehicle dies.

Or the vehicle may stay running for a while until you start turning on accessories (like headlights, a/c, wipers, etc.).

The battery light comes on and stays on the whole time the vehicle is running.

At night, when you turn on the headlights, both headlights and dashlights are very dim.


Here is how to test without any tools

Start the vehicle. Either jump-start it or charge the battery to get it started.

Open the door and leave it open so that the dome light can come on and stay on.

Disconnect the jumper-cables.

Go back to the inside of the vehicle and eyeball the dome light.

If the vehicle stayed running after disconnecting whatever it was that got it going, then notice the dome light's intensity.

Now turn on the headlights and notice the light's intensity once again.*

The light should dim a little and then resume its brilliance to the way it was before the headlights were turned on. If this happens the alternator is doing good.

If the light dims and DOES NOT return to its previous intensity and CONTINUES to dim, the alternator is faulty.

With the vehicle running and with the headlights still on...

Turn on the blower motor on high and notice the light's intensity once again.*

The light should dim a little and then resume its brilliance to the way it was before the headlights and the blower motor were turned on. If this happens then the alternator is doing good.

If the light dims and DOES NOT return to its previous intensity and CONTINUES to dim, the alternator is faulty and not charging the battery or supplying the vehicle's electrical needs.

If the alternator is BAD, as you turn on load after load (headlights, blower motor, wipers, turn signals, etc.) then eventually the dome light and the headlights will get very, very dim till the vehicle stalls.

If the alternator is not BAD, then the dome light and the headlights will stay on and brightly lit (after a slight dim as the load normalizes) no matter what you turn on.

It doesn't matter how discharged the battery is. After the vehicle is started, either by a jump-start or by charging the battery, this test applies.

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  #7  
Old 07-09-2012, 04:23 PM
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david_12121 david_12121 is offline
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Re: Bad alternator cause other problems? LONG

Quote:
Originally Posted by svxcess View Post
DONT DO IT!!!


This guy knows better...I did that with mine, guess I shouldn't have
But when I was testing mine, i didn't find any actual test that showed ripple in the system...my alternator worked, it kept the light on and at a constant amount, and it did all of that as long as the engine was on, but as soon as I shut it off, it would not start again...the problem was that it had ~10% of ripple(said the autozone battery tester) so it was producing a little over 12v, and that was not enough to charge the battery. That kept the car on, but was unable to charge the battery, therefore it would not be able to start the car up, even right after i shut it off
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DIY FTW!
1993 SVX 25th Anniversary Edition @+142k
-Rebuilt Tranny @135k
-Regasketed Engine @140k
-Enkei Raijin 18x8.5, with 255/35/18's @140k
-BC racing Coilovers (From STI's) @142k

Last edited by david_12121; 07-09-2012 at 04:30 PM.
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  #8  
Old 07-10-2012, 12:57 AM
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Re: Bad alternator cause other problems?

I think i just test the battery whit a volt meter.

But if i have a full charge battery and reset the ecu and then try to start it.
And let it run about 1 min and then check the ecu will this clear the knock sensor errors?

I should try to get some rebuild parts form mitsubishi try to send them a mail. After is a mitsubishi alternator. Maybe i am lucky.
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