silverz28camaro

iTrader: (20)

I have a 2000 Z28 Camaro, with the stall converter, ud pulley and only an alt.
the motor tends to rev quickly

Problem is when I make a pass at WOT sometimes the voltage drops off for a split second and doesn't charge. Chargin at idle is perfect, the problem only shows when I floor it , rpms rise quicky, and voltage drops, then comes back on .

its as if someone unplugs the alt. for 1 sec.

I noticed the alt. signal wire comes from the computer...has anyone wired it straight to the battery?

sjsingle1

iTrader: (1)

get a truck alt.....or bigger..........nuff sed

AlamoTA

iTrader: (10)

Is there an actual problem asociated with the momentary voltage drop? If your engine revs quickly, it may take your regulator a few seconds to catch up/balance out. It seems that your battery's normal 12 volts will cover the second that your alternator doesn't.

wssix99

iTrader: (5)

Sounds like a belt problem, particularly if you are running a different pulley on the alt.

If you are racing with specialized pullies, you'll want something like this to make sure you are keeping the proper tension: https://ls1tech.com/forums/generatio...ame-price.html

If you have a stock tensioner, you are relying on its spring to keep tension, which may not hold up under the shock of accelerating quickly.

sjsingle1

iTrader: (1)

i would think the belt would jump off rather than slip at WOT.........IMO

silverz28camaro

iTrader: (20)

I don't think the belt is slipping, no noises and I have a manual tension on it....

I might steal the alternator off my Dodge Ram and see what happenes.....

silverz28camaro

iTrader: (20)

I was kinda thinking this, when I do floor it and the motor revs, lights dim, and the gauge falls to the 11.0-12.0 range(hard to tell on the actuall reading) but its on a second maybe til it recovers.

The alt. "ON" wire comes from the computer...maybe the computer is sensing a slight voltage spike..or is tuning this wire off for a moment...

here is a pretty good wiring schematic...

I wonder if its a good idea to wire to a "key on" relay and to the battery, to try and bypass computer control...

I guess before I go swapping alternators I'll back probe the signal wire and see if it looses voltage at wot...if so then the alt. should be good and will just need a separate signal setup

http://chevythunder.com/19992002_ls1...s.htm#Charging System Schematics

silverz28camaro

iTrader: (20)

here is why the car revs so fast, no accesories and a small converter 9.5 in, car also has 11.4 compression

wssix99

iTrader: (5)

Hell - your alternator is so accessible, why don't you just pop it off and take it to an auto parts store to be tested. That will tell you instantly what kind of shape its in.

Do you have any accessories that draw a lot of power or notice any difference when the head lights are on/off? If not, then you should be fine unless something is defective.

How many miles are on it?

silverz28camaro

iTrader: (20)

Its pretty new, but its not oem, maybe 15,000 miles tops, I have less power drain then a factory camaro, less speakers, removed the amp, remove the air pump, removed ABS, so really the car should be easier to maintain a charge.

it only does it during a wot snap....if I roll into the throttle everything is on!

I'll prob the signal wire, its the only way to find out for sure if the alternator is being shut off, or if its shorting itself out.....

sjsingle1

iTrader: (1)

https://ls1tech.com/forums/generatio...-failures.html

if the alt cant keep up with what little load you have on it............its the alt.......and IMO the stock alt CANNOT keep with our cars .........a design failure by GM

wssix99

iTrader: (5)

The stock alternator can handle a stock car at full RPM just fine. Since you have reduced the loads on the electrical system and aren't revving higher than the car was designed, the laws of physics dictate that you should be fine on sizing.

However... your alternator is spinning slower at a given RPM range due to the UD pulley. This could be at the root of the issue but I'd still get the alternator checked first. Its not unheard of for voltage regulators to go bad quickly, especially if it was a reman. (For the record, I will never buy a reman alternator again. Too many problems in past cars.)

It looks like the alternator is the only belt driven accessory left, right? If so, and if your alternator tests out good, I'd go back to the stock pulley and see what happens. Buying a larger alternator may also solve the problem with the UD pulley on, but it WILL suck more energy from the engine to turn it. (I assume this would be a bad thing in your situation.)


BTW - I don't think your exciter wire is the issue. Its main function is to get the alternator going. Once its turning and generating power, it should keep things going internally: http://en.wikipedia.org/wiki/Alterna...ve_alternators

real82it

Thread Resurrection!

1995 LT1 trans am.......doing this same thing. At idle or cruise rpm, voltage is fine. WOT or quick rise in rpm, voltage drops to 8-9. Belt tension is fine.

Took alternator in today (OEM alternator)........alternator tested fine.

I inspected the exciter wire, it looks fine.

Any ideas? Trying to avoid spending $150 on an alternator if I can.

LS6427

iTrader: (2)

Don't rule out a weak battery cell....

.

1999nbmZ

Are you sure that this isn't built into the design of the car? I know that the computer is programmed to drop out the AC compressor at WOT, to free up more power. Makes sense that they would unload the alternator as well...

Need4Camaro

iTrader: (1)

Possible, but I kinda doubt thats it. If it were he should see problems throughout the RPM range and not just WOT. Plus it would be obvious when he cranks the vehicle too. Also my stock alt will run my 99 Z28 at 13.5 Volts on a dead battery no issues, done it before... not RECOMMENDED, but it will work.

Trust me when I say after multiple WOT experiences, dumping alt power and risking frying sensitive components was NOT apart of the design. (you risk taking out components with too low of voltage just as much as you do with too high aswell, my power windows literally caught fire when my exciter wire was broken without my knowing and the alt died with it)
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To the OP I may have missed it but when did these problems start? I notice UD Pulley, Electric WP, and what appears to be a stock alternator. Im pretty sure the alt in this configuration is getting more than its fair share. I'd just upgrade to a truck alt at the minimum, even if it doesn't solve the issue... it's extra insurance.

If its not the alt failing, its the belt and pulleys. Only other thing it could be really. It "sounds" like your belt is slipping alittle bit at WOT due to the increased inertia with much less resistance (less pulleys / UD pulley) plus the shock of force thats presented in the short instance of going WOT.. Try doing this... Slowly ease the car into WOT, as in just gradually press the pedal until the car goes WOT and dont just stomp on the gas, see if the issue is still present when you reach WOT. If it is, it's the alt. If it isn't, its the pulley / belt combo.

69-chvl

iTrader: (11)

Just went through this...alternator was just tapped-out amp wise at WOT. This was a 105a truck unit. Went to a 145a truck unit and problem solved!!

real82it

I decided to just try and replace the alternator to see what happens.

New alternator, issue is fixed.

I inspected the wiring when I was in there, no obvious issue.

That is a first. I have had alternators fail to charge at low rpm, than charge as rpm increases. Never the other way around.

Not sure what caused it.....maybe a bad internal exciter or regulator? Anyway, happy issue is solved.

Need4Camaro

iTrader: (1)

probably the higher amperage demand at higher RPMs, possible pulley issue were too much for the regulator that was on its way out.