Voltage Drop at WOT
Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
Voltage Drop at WOT So I have a issue that I cannot seem to correct where at WOT I am seeing a voltage drop above 4000RPMs which will cause the lights to dim and just before red line, the check gauges light will come on. It will return to normal if the accelerator is released. Cruising around the problem will not surface at all. So here's what's been done so far:
I have another alternator coming to swap out to see if that is the problem for I've never seen this issue before so that is what I *hope* the issue is. I'll also be replacing the battery just to make sure but I can't see what that would cause the issue. Only other thing I was thinking was belt slippage but other then the crank, every pulley is clean and brand new including the belt so that kinda rules that out.
The car is slightly modded with the usual bolt-ons and was tuned and I don't have much in the way of electronics to draw lots of power.
Is there anything else I should be looking at while I got the car up and replacing the alternator like grounds or such anyone can think of?
- Brand new GM alternator (lifetime warranty)
- New power steering pump
- 1yr old GM water pump
- New GM belt tensioner
- New GM belt & new Gatorback belt
I have another alternator coming to swap out to see if that is the problem for I've never seen this issue before so that is what I *hope* the issue is. I'll also be replacing the battery just to make sure but I can't see what that would cause the issue. Only other thing I was thinking was belt slippage but other then the crank, every pulley is clean and brand new including the belt so that kinda rules that out.
The car is slightly modded with the usual bolt-ons and was tuned and I don't have much in the way of electronics to draw lots of power.
Is there anything else I should be looking at while I got the car up and replacing the alternator like grounds or such anyone can think of?
Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
Wow, never would of guessed a junkyard one would be better then one remaned. I've seen lots of threads here on the subject but not one really solves the issue that I can see.
Belt slippage is the most common response but I know that it isn't the issue. It's gotta be the brush springs since it only happens at high rpm's.
Belt slippage is the most common response but I know that it isn't the issue. It's gotta be the brush springs since it only happens at high rpm's.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Wow, never would of guessed a junkyard one would be better then one remaned. I've seen lots of threads here on the subject but not one really solves the issue that I can see.
Belt slippage is the most common response but I know that it isn't the issue. It's gotta be the brush springs since it only happens at high rpm's.
Belt slippage is the most common response but I know that it isn't the issue. It's gotta be the brush springs since it only happens at high rpm's.
Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
New alt going in tomorrow so hopefully that is what the issue is.
I also replaced the idler pulley today while I got it apart for it looked scorched and it didn't freely rotate so the bearing must be going out and is binding.
Strangely when I want to the parts store the one listed for my year was completely wrong (and $58). The inside of the pulley facing outwards was straight whereas it needs to be at an angle going down for the dust shield to sit correctly. Had to lookup one for a 2000 Corvette and it works perfectly (and only $20).
I also replaced the idler pulley today while I got it apart for it looked scorched and it didn't freely rotate so the bearing must be going out and is binding.
Strangely when I want to the parts store the one listed for my year was completely wrong (and $58). The inside of the pulley facing outwards was straight whereas it needs to be at an angle going down for the dust shield to sit correctly. Had to lookup one for a 2000 Corvette and it works perfectly (and only $20).
Trending Topics
I had a similar problem a couple years back. I went through 3 alternators and the buick tensioner pulley trying to find the problem. Turns out a katech tensioner was the answer. Idk if this is your problem but couldnt hurt to try, plus the katech piece is really nice looking and its about the same price as an oem tensioner. Good luck.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
Swapped out the alternator and it performs as it should so it must of been a bad rebuild.
Just a precaution I also replaced:
Battery
Battery terminals
Idler pulley
Tensioner pulley
Belt
PS pump
Tightened up all the grounds
New spark plug wires
Removed the exciter wire from the plastic wrap so it wasn't as tight and has a little more slack
Might of gone a little overboard but didn't want to take a chance.
Just a precaution I also replaced:
Battery
Battery terminals
Idler pulley
Tensioner pulley
Belt
PS pump
Tightened up all the grounds
New spark plug wires
Removed the exciter wire from the plastic wrap so it wasn't as tight and has a little more slack
Might of gone a little overboard but didn't want to take a chance.
Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
Well, went through the entire system again. The brand new GM alt burned out after only one WOT test run and was not charging the battery. Everything else checked good so as it turns out threw in a rebuilt alt that has better internals and so far she's holding steady as it should.
Thread Starter
12 Second Club
Joined: May 2004
Posts: 72
Likes: 0
From: Florida
If it happens again I'll just have it locally rebuilt with high-output internals and be done with it.
Just a quick note, make sure your power steering lines are not leaking. A lot of people have issues with leaking pumps/lines and the alt is right under it.. I had this issue along with 3 alt swaps till the high pressure line fully showed its leak and drained the tank right into the alt taking it out...
Do This 
I hope you have fixed the issue, but check this out, it fixed my voltage drop at WOT.
http://www.calspeedperformance.com/p...cei-102130.htm
http://www.calspeedperformance.com/p...cei-102130.htm