WOT equals no voltage

[BigCars4Ever]

So I'm having a problem. When I hit WOT my voltage drops and doesn't come back up for several seconds. If I stay in it long enough I start to loose my headlights and power for my Sirius radio. Volt gauge drops to a little below 12V. Is my alternator going bad? Is the one way bearing becoming a no way bearing? Any ideas? Thanks in advance.

[ChiTownMaraud3r]

I believe your alternator is shutting down at WOT, and if your battery is old, or connection at the terminals is dirty, that is why you're seeing a dip in voltage. The alternator clutch can be heard when doing a WOT burnout and letting off the gas suddenly.

[JoeBoomz]

The tune can be configured to shut off the alt at WOT. It's a stupid feature and best to have your tuner disable it.

[Limited360]

This means your battery is weak if things are dropping out that bad... my guess would be to get your battery checked!

[BigCars4Ever]

I guess since the car sits a lot more the battery is not ever fully charged anymore. I never noticed this when I drove the car every day. Guess I need to use my battery tender a little more often. Thanks!

[Jolly Roger]

BC4E,
I seem to recall a feature on my 5.0 liter Capri that shut down a lot of power robbing accessories,
including the alternator at WOT.
Could this feature be on the MM also?
Could this be what's happening here?

Just my 4.6 cts.;)

[whitey]

jollyroger: the alternator shuts off exactly for that reason, to help with power robbing at wot. it came like this from the factory, and some people turn off(which means the alternator keeps running at wot)this feature in a tune. ive heard mixed reviews, some say that the alternator is being damaged at such high speeds/rpms, some say it doesnt even matter. i personally dont have it turned off and have never had an issue, however, me and richardp were drag racing at cecil earlier this year and he was having trouble restarting his car after it was sitting in the waiting lanes after a few runs....jumped the battery and it was all good.

[MMBLUE]

I think I have one for you. I'll dig in the garage and get back with you. ;)

[Vortech347]

My 03 and 04 did it. Considering that you aren't at full throttle for to long unless you're doing a 2 mile pull don't worry about it.

[EMAS]

Definitely not a problem with the alternator as the computer controls it's output voltage to maximize power available to put to the wheels.

The problem is your battery.

[Blk04MM]

Listen to those who said it's the alternator cutting off at WOT. THEY ARE CORRECT. It can easily be disabled by a tuner. End of story don't go getting a new battery etc...

To better prove it's NOT your battery go get a free battery test. It'll check out fine.

Happy Holidays

[MOTOWN]

Some seem to be completely missing the point here, yes some tunes shut off the alternator @ WOT, but a fully charged battery isnt going to loose headlights the minute you go WOT, thats a bad/discharged battery.

[EMAS]

Some seem to be completely missing the point here, yes some tunes shut off the alternator @ WOT, but a fully charged battery isnt going to loose headlights the minute you go WOT, thats a bad/discharged battery.


Actually it is some tunes that don't shut off the alternator at WOT as shutting of the alternator at WOT is the factory strategy.

[whitey]

Some seem to be completely missing the point here, yes some tunes shut off the alternator @ WOT, but a fully charged battery isnt going to loose headlights the minute you go WOT, thats a bad/discharged battery.


Actually it is some tunes that don't shut off the alternator at WOT as shutting of the alternator at WOT is the factory strategy.

Yes, and yes. Motown is right about the battery, the headlights and stuff shouldn't die the moment you punch the pedal.

[RacerX]

Are the lights and radio cutting out completely or just dimming? If they're just dimming, it's normal. If they're cutting out, you definitely need a new battery. Unless you're supercharged, N2O, etc., don't worry about the tune. It is Ford factory settings in the tune that shut off the alternator at WOT. On ALL Marauders and other Ford vehicles for that matter. I datalogged at the track and saw my voltage dropping into the 11s. Bought a new battery and found NO change. This is when my search led me to the WOT shutoff feature. I changed it in my tune to be on all the time. This way my fuel pump, injectors and anything else gets at least 12v all the time. My changes:

http://www.mercurymarauder.net/gallery/data/579/medium/Alt.jpg (javascript:;)

[RF Overlord]

Definitely not a problem with the alternator as the computer controls it's output voltage to maximize power available to put to the wheels.

The problem is your battery.^^^This^^^

[burt ragio]

Yes, have to agree alt shut off at full throttle to save one to two hp . My custom tune has this feature built in I hate it. Running the highways at night nothing nicer when no one is out to do a few full throttle blasts for a mile. Hate it when you out run the headlights.

[whitey]

Has anybody ever damaged/over spun their alternator by having the alternator on at WOT? I read somewhere about it...

[fastblackmerc]

Has anybody ever damaged/over spun their alternator by having the alternator on at WOT? I read somewhere about it...

Don't you think the engineers at Ford considered all the possibilities when they designed the system?

[whitey]

Don't you think the engineers at Ford considered all the possibilities when they designed the system?

Umm...exactly. they designed it to turn off at WOT, not stay on. My question continues.

[JoeBoomz]

Has anybody ever damaged/over spun their alternator by having the alternator on at WOT? I read somewhere about it...


To me an alternator is cheaper than a motor when your fuel delivery doesn't have the power it needs at WOT.

[RF Overlord]

Has anybody ever damaged/over spun their alternator by having the alternator on at WOT? I read somewhere about it...The alternator is not physically disconnected from the FEAD at WOT, it just doesn't produce power. It's still turning at the same speed at WOT whether it's on or off.

[whitey]

The alternator is not physically disconnected from the FEAD at WOT, it just doesn't produce power. It's still turning at the same speed at WOT whether it's on or off.

Ok, i thought maybe it was clutched somehow and would just free spin at WOT, in order not to spin the innards of the alternator.

[RF Overlord]

The clutch you're thinking of is the over-running clutch, which is designed to allow the alternator to continue spinning when the throttle is suddenly closed at high RPM, or when the engine slows due to an upshift. It's more for improving belt life and eliminating the belt chirp on upshifts.

[whitey]

Thanks for the info sir!

[Vortech347]

Are the lights and radio cutting out completely or just dimming? If they're just dimming, it's normal. If they're cutting out, you definitely need a new battery. Unless you're supercharged, N2O, etc., don't worry about the tune. It is Ford factory settings in the tune that shut off the alternator at WOT. On ALL Marauders and other Ford vehicles for that matter. I datalogged at the track and saw my voltage dropping into the 11s. Bought a new battery and found NO change. This is when my search led me to the WOT shutoff feature. I changed it in my tune to be on all the time. This way my fuel pump, injectors and anything else gets at least 12v all the time. My changes:

http://www.mercurymarauder.net/gallery/data/579/medium/Alt.jpg (javascript:;)

Yup. The only time I would make the alt on 100% of the time was if running forced induction because you don't want voltage to drop at the fuel pump because their duty cycles are quite a bit higher.

[EMAS]

Are the lights and radio cutting out completely or just dimming? If they're just dimming, it's normal. If they're cutting out, you definitely need a new battery. Unless you're supercharged, N2O, etc., don't worry about the tune. It is Ford factory settings in the tune that shut off the alternator at WOT. On ALL Marauders and other Ford vehicles for that matter. I datalogged at the track and saw my voltage dropping into the 11s. Bought a new battery and found NO change. This is when my search led me to the WOT shutoff feature. I changed it in my tune to be on all the time. This way my fuel pump, injectors and anything else gets at least 12v all the time. My changes:

http://www.mercurymarauder.net/gallery/data/579/medium/Alt.jpg (http://javascript<b></b>:;)
It seems as though you've traded drain on the engine at WOT for none at idle. An idle voltage of 12.1 means that your battery is discharging at idle. In other than WOT conditions you want a minimum alternator voltage of 13.6~13.8 as that will maintain but not charge the battery. I'd also change the voltage to indicate a charging good be no lower than 13v. A fully charged lead acid "12 volt" battery has an open circuit voltage of 12.77 volts.

The computer monitors the voltage and automatically compensates the pulse width to the injectors and fuel pump to maintain consistent operation of those items.

[RacerX]

That is likely a min clip since mine is always at 14.1v @ idle. :beer:

[EMAS]

That is likely a min clip since mine is always at 14.1v @ idle. :beer:

It is OK, well actually preferred for the voltage to drop to that 13.6-13.8 range once the computer senses that the battery has been fully charged. Yes some of that is to increase MPG incrementally but it also makes the battery last longer. Every notice how many people got 8,9 or even 10 years out of their factory Marauder battery while people with vehicles from lesser brands don't get anywhere near that life out of their OE battery. Yes some of it is due to the fact that those lesser mfgs spec out the cheapest battery possible while Ford doesn't save a buck there, but it is also the charging system strategy that contributes to the long battery life.

[chief455]

So I'm having a problem. When I hit WOT my voltage drops and doesn't come back up for several seconds. If I stay in it long enough I start to loose my headlights and power for my Sirius radio. Volt gauge drops to a little below 12V. Is my alternator going bad? Is the one way bearing becoming a no way bearing? Any ideas? Thanks in advance.
The previous replies on WOT cut off are probably accurate, but you describe 'staying in it...' that is not likley at WOT the entire time, and alternator function should be restored at anything less than WOT.
The loss of lights and radio is not a good reaction for going WOT, even for several seconds.
Personally, I would not accept this as normal, and keep looking for a cure.
I found voltage drop during WOT while logging data, cleaned all my terminal/grounding connections very well and restored ~1 volt at WOT on following data logs.
I've found the most accurate test of the alternator during WOT(or almost) - is to run a muliti meter into the car and let a passenger monitor the output.
Your car gauge reading can be tainted by the long path through factory electronics, even data logging voltage through the OBDII port may not always be fully accurate.

[RacerX]

S'aight! It's normal for me. I got this beauty:
http://www.powerbastards.com/products.asp?cat=125978
PC'd Black. Had it in for almost three years now.

[chief455]

S'aight! It's normal for me. I got this beauty:
http://www.powerbastards.com/products.asp?cat=125978
PC'd Black. Had it in for almost three years now.
:drool::drool:

[MyBlackBeasts]

To me an alternator is cheaper than a motor when your fuel delivery doesn't have the power it needs at WOT.

When I had tune done I had this disabled. The power saved by cutting out alt is negligible. Headlights are brighter @ 14v vs. 12v.

In the dark, having headlights dim @ WOT drove me nuts. Rather buy an alt sooner than hit a deer.

[EMAS]

When I had tune done I had this disabled. The power saved by cutting out alt is negligible. Headlights are brighter @ 14v vs. 12v.

In the dark, having headlights dim @ WOT drove me nuts. Rather buy an alternator sooner than hit a deer.

Not turning off the alternator will not make your alternator wear out any sooner. The parts that wear out in an alternator are the brushes and bearings. All the computer does is send a signal to the regulator to lower it's output voltage to the point where power will be drawn from the battery instead of the alternator. The bearings are still spinning and the brushes are still rubbing on the commutators.

[screamn]

S'aight! It's normal for me. I got this beauty:
http://www.powerbastards.com/products.asp?cat=125978
PC'd Black. Had it in for almost three years now.

Thanks for posting. I will definetly be ordering one of these when mine craps out but sooner than later. :beer:

[MyBlackBeasts]

Not turning off the alternator will not make your alternator wear out any sooner. The parts that wear out in an alternator are the brushes and bearings. All the computer does is send a signal to the regulator to lower it's output voltage to the point where power will be drawn from the battery instead of the alternator. The bearings are still spinning and the brushes are still rubbing on the commutators.


That is know. Was responding to prior comments.

Don't care about wearing out sooner (if it did) or the loss of 0.0000000001 hp. More important to have full headlight illumination @ WOT. An alt is cheaper than a deer totaled MM.

[Vortech347]

Why would you go WFO if you think there are deer close?

[MyBlackBeasts]

Why would you go WFO if you think there are deer close?

Rural = deer are unknown factor. Like drunk drivers.

They can be every where, no crystal ball when hitting the go-go pedal.

Doing some night-time 0-60 WOT's to put the smile on your face (the reason we own the things) is a-ok with normal headlights but when the alt kicks out you overdrive the headlights @ 45mph. Now you are in danger of deer or any road debris ruining your day...

[lifespeed]

S'aight! It's normal for me. I got this beauty:
http://www.powerbastards.com/products.asp?cat=125978
PC'd Black. Had it in for almost three years now.

If the pictures are accurate, that does not appear to have the One Way Clutch, which I think is a nice item for general driveability and accessory smoothness.

[EMAS]

If the pictures are accurate, that does not appear to have the One Way Clutch, which I think is a nice item for general driveability and accessory smoothness.

The overrunning clutch is there to provide accessory smoothness in addition to being able to run lower tension and thus reduce drag.