WOT voltage drop

[Wenke Racing]

I'm guessing the alternator is getting weak but thought I would run it by the experts. When my MM is driving under normal conditions it charges around 14 V but when you go wide open throttle it drops to 12v. It does it every time, I don't hear the belt slipping and it appears to be in good shape and the tensioner has good tension. Its only under a load will not do it in a free revving condition. Thoughts?

[Kennyrauder]

The alternator does this by design....you run on the battery under WOT. Best Regards Kenny.

[fastblackmerc]

The alternator does this by design....you run on the battery under WOT. Best Regards Kenny.

Correct... working as designed.

[RF Overlord]

^^^what they said^^^

[RacerX]

That can be changed in the tune. Mine does not shut off under wot. This gives the injectors and fuel pump more voltage to work with if you need it under wot.

[Curless]

They do this so there is no belt draw on the engine, my drag cars do this as well. If you have a good battery you'll be fine...you will also notice that your air conditioning shuts off at WOT as well.

[na svt]

The alternator does this by design....you run on the battery under WOT. Best Regards Kenny.

It's not by design and the computer doesn't control the alternator output. My alternator used to drop voltage as the RPMs increased and the cause was worn stators which were bouncing on the rotor. I had the stators replaced and now it holds 14 volts to 7000rpm.

[shawn.criswell]

Bet the a/c stops blowing cold air to. By design to reduce belt drag and keep the RPM roaring. Its in the article about the MM.

[RF Overlord]

It's not by design and the computer doesn't control the alternator output. Yes it is and yes it does.

If you're turning 7000 RPM, then you prolly have a tune, yes?

[na svt]

Yes it is and yes it does.

If you're turning 7000 RPM, then you prolly have a tune, yes?

The a/c does shut off as it does in most other cars. However, I've had the alternator discussion with someone who know alternators and the Marauder alternator is not controlled by the computer and should put out 14v at any rpm level. Also, the fact that my alternator puts out 14v at 7000rpm proves my point.

[RF Overlord]

That only proves YOURS doesn't shut off. It's well known that the alternator in the Marauder is PCM controlled. If you have a tune, the WOT shutoff is prolly disabled, as Racer X said above.

[na svt]

That only proves YOURS doesn't shut off. It's well known that the alternator in the Marauder is PCM controlled. If you have a tune, the WOT shutoff is prolly disabled, as Racer X said above.

I dunno what to say other than a alternator expert said the marauder alternator was not computer controlled. The only change I made to mine was to get rid of that heavy ass clutched pulley and to replace the worn brushes. There were no changes made to the tune prior to or after fixing the brushes. :dunno:

I'm far from an electronics expert so I'm only passing on my experiences and what an expert told me.

Is there anything written that states the alternator shuts down?

[na svt]

If the computer does shut it down when does it do so: A certain RPM, at full throttle?

Like I said, mine was shutting down, it was repaired and now it provides 14v at all throttle settings...life is good. BTW, I've seen th voltage drop on Cobras also.

[RF Overlord]

Here's (http://www.napaechlin.com/Ford-PCM%20Controlled%20Charging%20 System/Content.aspx) a nice write up on how it works.

[na svt]

Here's (http://www.napaechlin.com/Ford-PCM%20Controlled%20Charging%20 System/Content.aspx) a nice write up on how it works.
well ****, *** ****, ****** ******, and I thought I knew it all:beer:

That option should be done away with.

[lifespeed]

I dunno what to say other than a alternator expert said the marauder alternator was not computer controlled. The only change I made to mine was to get rid of that heavy ass clutched pulley . . .

You should have replaced the clutched pulley, not eliminated it. Tensioner and idlers too.

[na svt]

You should have replaced the clutched pulley, not eliminated it. Tensioner and idlers too.
My tensioners are good as are the idlers. The pulley I installed has a 3.2" diameter. I'm not a fan of the clutched pulleys. I guess they aren't clutched, they should be referred to as ratcheting since they only work in one direction.

[Joe Walsh]

My tensioners are good as are the idlers. The pulley I installed is a 3.2" in diameter. I'm not a fan of the clutched pulleys.
I guess they aren't clutched, they should be referred to as ratcheting since they only work in one direction.

Yep,
The term "clutched" alternator pulley makes people think that it can be controlled like an A/C compressor's pulley.
It's just a mechanical diode......to use a fancy term.

[lifespeed]

My tensioners are good as are the idlers.

"Good" as in have been replaced, or "good" as in "I don't know they are worn or what difference it would make"? Do you know what the purpose of the over-running clutch on the alternator (AKA mechanical diode) is?

My experience has been that having these components in good working order greatly smooths the accessory drive system under transient conditions, ie hard acceleration and shifting. They eliminate belt squealing and excessive loading also.

I don't think there are any cars made with solid alternator pulleys anymore. But what do all those engineers know . . .

[na svt]

"Good" as in have been replaced, or "good" as in "I don't know they are worn or what difference it would make"? Do you know what the purpose of the over-running clutch on the alternator (AKA mechanical diode) is?

I don't think there are any cars made with solid alternator pulleys anymore.

Cobras, Mach 1s and the other mustangs of the same years as Marauders had "solid" pulleys.

My tensioner and idlers are were new at the time.

[whitey]

I've read an article that pretty much explained why the alternator pulley is clutched, something to do with rpm's of the motor and rpm's of the pulley. IIRC the alternator would spin at like 19,000rpm, which overloads it, and would cause a lot of excessive wear since they weren't made to spin that fast.

[Joe Walsh]

I've read an article that pretty much explained why the alternator pulley is clutched, something to do with rpm's of the motor and rpm's of the pulley. IIRC the alternator would spin at like 19,000rpm, which overloads it, and would cause a lot of excessive wear since they weren't made to spin that fast.

Here is one of the earlier threads/discussions/arguments about the 'clutched' alternator:

http://www.mercurymarauder.net/forums/showthread.php?t=23095&highlight=alternator

..

[EMAS]

I've read an article that pretty much explained why the alternator pulley is clutched, something to do with rpm's of the motor and rpm's of the pulley. IIRC the alternator would spin at like 19,000rpm, which overloads it, and would cause a lot of excessive wear since they weren't made to spin that fast.

The overrunning clutch on the alternator is to allow the alternator to spin faster than the engine is trying to drive it. That allows a lower belt tension to reduce the drag caused by the belt w/o the belt slipping when there is a shift at WOT. That is why they didn't put them on vehicles equipped with manual transmissions since they do not have as larg and quick of an rpm drop when shifting.