high rpm voltage drop, new alternator or volt reg upgrade?

[DSG2003Mach1]

on the dyno this weekend and the tuner pointed out in the higher rpms my alternator is dipping into the 12.5 volt range.

My alternator is a couple years old but very very very few miles on it as it was in pieces most of the time Ive had it.

should I just replace the alternator and see what happens?

I saw while searching a few other complaints about this and a link to this voltage regulator upgrade

http://www.americanmuscle.com/paperf...ar=1996&model=

edit - i went and looked and its a power master brand alternator, might just try replacing it with a ford piece first

[01yellerCobra]

Are you running an overdrive crank pulley?

[DSG2003Mach1]

ive always had stock size pulleys on everything. Unless the Gi Joe 8 rib kit had a smaller 8 rib for the alternator that pulley should have always been the stock size as well

[01yellerCobra]

I was just asking because I ran an overdrive crank pulley with stock alternator pulley and it would overspin the alternator and cause voltage to drop off. Although 12.5 really isn't bad. I've been told above 12 is good. Mine was dropping down to 11.

[Mach828]

I would just take it off and get it tested at autozone. Mine tested as faulty when I was having low voltage issues.

[not a gt]

I like the regulator upgrade, good to bookmark as a "just in case".

[Nekasrof]

Yep, been there. I had voltage drop to 12.1. On a boosted car, you need 13v. Pumps are rated at 13 so I'd get the regulator upgraded or get another one.

[not a gt]

Hey DSG, if I pull up Battery Voltage on the AeroForce gage, if I do a WOT run, is that a good reading on what voltage is at WOT?? Will the reading be the same thing you are talking about here? I was gonna go out to the hard road tomorrow and see what value I get. Could this as well cause the slight stumble/hesistation between shifts at WOT I sometimes get? Great thread, I didn't know any of this.

Mine tested as faulty when I was having low voltage issues.
What issues were you having 828??

[DSG2003Mach1]

Originally Posted by 01yellerCobra

I was just asking because I ran an overdrive crank pulley with stock alternator pulley and it would overspin the alternator and cause voltage to drop off. Although 12.5 really isn't bad. I've been told above 12 is good. Mine was dropping down to 11.

yep, Im aware of that issue, as the post I quoted below says with my fuel system it needs to stay 13+ to keep my MAF and pumps working properly

Originally Posted by Nekasrof

Yep, been there. I had voltage drop to 12.1. On a boosted car, you need 13v. Pumps are rated at 13 so I'd get the regulator upgraded or get another one.

Im going to order a new Ford unit and go from there

Originally Posted by not a gt

Hey DSG, if I pull up Battery Voltage on the AeroForce gage, if I do a WOT run, is that a good reading on what voltage is at WOT?? Will the reading be the same thing you are talking about here? I was gonna go out to the hard road tomorrow and see what value I get. Could this as well cause the slight stumble/hesistation between shifts at WOT I sometimes get? Great thread, I didn't know any of this.

the stumble/hesitation between pumps - does your setup still have the PPRV (the check ball system) with the fuel pump stuff you did? Voltage on the aeroforce should work but it may be difficult to keep a close enough eye on that and the road to catch it. There is a way to make the aeroforce record an input and play it back but Ive never done it. It may be easier to get your Xcal working again and datalog it to the laptop. Log RPM and voltage

[not a gt]

I think the PPRV is deleted, I have this setup with 4 holes drilled and your BAP. It doesn't happen all the time, I just wanted to verify the voltage, when you look at it after install we have a lot of s**t drawing from battery (and I have HID, BAP, neon, etc). Mine is weird since it isn't a constant thing, out of nowhere it will do a slight "miss", with car running at idle what should we see across battery? Hell, not scientific, but I could hook meter across battery under hood and increase throttle by hand and see reading or that won't really work either? Hell, this is YOUR thread, good luck and hope a alt solves that minor issue!!!

http://www.lethalperformance.com/sho...-04-cobra.html

Probably not an issue, Kurgan had no problem tuning at 82% FPDC, could be just a gremlin

[DSG2003Mach1]

Originally Posted by not a gt

I think the PPRV is deleted, I have this setup with 4 holes drilled and your BAP. It doesn't happen all the time, I just wanted to verify the voltage, when you look at it after install we have a lot of s**t drawing from battery (and I have HID, BAP, neon, etc). Mine is weird since it isn't a constant thing, out of nowhere it will do a slight "miss", with car running at idle what should we see across battery? Hell, not scientific, but I could hook meter across battery under hood and increase throttle by hand and see reading or that won't really work either? Hell, this is YOUR thread, good luck and hope a alt solves that minor issue!!!

http://www.lethalperformance.com/sho...-04-cobra.html

Probably not an issue, Kurgan had no problem tuning at 82% FPDC, could be just a gremlin

ya but feeding the beast under load vs reving at idle isnt the same thing so checking with a volt meter at the battery probably wouldnt be accurate. I remember reading a few different hesitation between shift issues and such over the years but I just dont remember the details

[not a gt]

Update??

[DSG2003Mach1]

new alternator is on but the car hasnt been run yet due to getting screwed on leaky fuel fittings