I had bought oneof Silverotors FD alternators for my S4, and I am having a problem with the voltage. When I first start the car up it revs to around 1700rpm for warm up. While doing so my wideband will read voltage during the warm up and it reading high 9's to low 10's. AFter a few minutes of warm up I reved the engine alittle, somewhere around 2500-3200rpm, and the voltage shot up to the low 13's.

I had this problem when I first tried to install it about a month ago when I was reinstalling my engine, but I put the S4 alt back in so I did not damage anything. It did the same thing, read low volts until it was reved..

What could cause this? The wires were all soldered(sp) and wrap with alot of electrical tape. The wires are hooked up properly as well. Will this damage anything?

When I have the S4alternator in the voltage is alright in the low 11's during start up and driving..

 

low 11's....low 11's!...I dont think that's normal man. My gauge reads 12 at start up , and then goes up to 14-15 after warm up. And it stays there.....I never goes under 12?

 

maybe you connected the wires to the back of the alternator backwards

 

Dittos. The excitation wire is in the wrong position. If its a series five alternator...the excitation wire should be the one on your left. Left being you facing the front of the alternator.

 

When you are driving... the voltage should be in the high thirteens.

 

My car is a S4, so when I wired the FD connector to it I did it according to the write ups, black wire to top FD connector(not unless the write ups are wrong). I also had to use a S5 B post, becuse the FD Bpost would not clear the intercooler.

The wideband only read the voltage at start up, so that is where I am getting the reading from, I am not sure how it is while cruisng...

 

Explain where the black/white wire and the white/black wire are located on the alternator.

I'm misunderstanding *black* wire. What wire is that? The only black wire is the one on the altenators output post. Large black wire there. The others are black/white and white/black. One is excitation, the other a ground signal wire to the CPU.

 

you using a bigger pulley than OEM? if the alternator's not spinning fast enough to produce sufficient voltage above & beyond the battery's static voltage, you'll get those low voltage problems

 

I am assumming the black wire in the write up is the one that is black with the white stripe. I have that one soldered to the yellow (top wire) of the FD alt plug.

I am using the stock pulleys, other than the dual belt pulley that I got with the FD alt from Silverotor (which I assume is the stock size). Like I said before, the voltage is low until the engine gets reved higher, after that it is fine. Its like if say around 2500rpm there is a switch and the voltage raises to about 13 volts, and after that the volatge is fine (even at idle). Its just when the car is first started, after I rev the engine to about 2500 all is good. Does that help any?

 

internal voltage regulator in the alt playing games with ya...if it pushes a charging voltage after you rev it & it "fixes" itself, I wouldn't worry too much, just keep an eye on the voltage gage...

 

See I don't really have a voltage gauge, I just know the volts when the wideband o2 is warming up, it gives me the voltage. BTW its the Innovate LM-1, if the voltsa are in the high 9 to low 10's it reads "Warming" then when the volts are somewhat adequate (after I rev it) it starts the Warm up, which at that time for the 10 seconds or so it read about 13-13.4 volts. And as long as I do not see the "warming" on the wideband the volts are atleast 11volts.

I had contacted Silverotor to see what he had to say, but I still have not recieved a reply yet. I was thinking it had something to do with the volatge regualtor. Could it just need like broken in? Cause I remeber reading his big thread in the forsale section saying about when they are first used amps can be as high as 120 but tend to go down to about 90-100 amps after getting broken in....

 

if it'll ease your mind, get a multimeter on the battery posts right after you start it (when you think the voltage is low), and see what ya get

 

So the volatge at the battery and the alt should be about the same right? And say it is 12 volts there then everything is good?

I was driving it for a bit and now I noticed that when I come up to a stop the enigne rpms drop low to about 400-500rpms instead of about 600-700rpms. But it quickly comes back up to my idle of 750...

 

ummmm.... I think you are reading air fuel ratios...... between 9 and 12.... and not volts
get a volt meter

 

eyecandy, my apoligies for the delayed response. I have mentioned In another thread that I have been super busy but I'm back In action. I PM'd you last night. Did you not receive It?

Basically, I outlined that If your voltage to your Battery" in the high 9 to low 10's" something Is seriously wrong with either your Battery Itself our the Instrument used to test It Is not a "valid" Indicator. I posed this as a possibility.

I was more Inclined to believe that you have mis-wired your Harness Plug leading to your Voltage Regulator. You've assured me that Is Intact. I did forget to let you know that the wires coming out of the Harness Plug that I supply *sometimes* differ In colours as opposed to authentic Harness Plugs that came stock In the FD Alternators. Perhaps you mistakingly misunderstood the wire to be matched was from the Harness Plug, rather than the stock Harness? I'm just shooting Ideas here but this sounds simular to when I drove my car for 2 weeks without the Harness Plug to my FD Alternator (Aaron Cake and I wired In my Microtech LT-8 as I saved the Alternator Harness for after). I had the exact same symptoms as you currently have. It was after I wired In the Harness Plug - I was fine.

Besure to update this thread or let me know what you did to correct this matter, but please - double check the wiring to the Voltage Regulator.

 

The black wire w/ white stripe goes to the top plug on the FD alt right? And the white w/black stripe goes to the bottom then?

If so then the wiring is all fine, Like I said in the pm does it just need broken in? Cause it has seemed to get a little better as I have been driving it...

 

Sorry about my misunderstanding.
I know what a series four connector looks like and what a series five looks like and where the wires should go.
I do not know squat about how the arrangement is on a 93-95 FD looks like.
The series five has each wire along side each other. The series four has one wire above the other.
And a FD I've no idea, although I tried to download the FD wiring this moring off the net, the net was not obliging me.

Just from personal experiece....I've by accident run alternators without the plug on the back for extended periods of time. They seem to charge once up to speed, but in the beginning they read low.....much as if they are missing some excitation voltage to get started charging.

 

I could be wrong, but I'm not sure If Alternators can be broken In. What are the total amount of kilometers you've racked up on your FD Alternator?

 

I would have to say about 50 miles (80-90 kilos) since last night when I installed it... It seems like it is getting better, so I am going to run it alittle more before I do a load test on it...

 

Ok well I have be watching and checking the voltage daily when I strat the car up and when I come home after a drive, and it seems to be doing alot better. Although everyonce and awhile the rpms will still drop a bit when I come to a stop, and I still get the lights dimming when i apply the brakes when idling...