I have a problem with my alt... when cold starting the car, it will go to 14ish volts right away. But if i start the car when it's even a tiiiny bit warm yet, i need to rev it to about 3700 rpm to get it to start charging... then it's ok. i just finished installing my efan yesterday so i'll be upgrading to the fd alt soon. but it's been doing this for a long time. any ideas?

 

umm..... FD alt maybe?

 

He just said he's going the FD alternator route. I can't think of any legit reason an alternator would need your engine to be at 3700 rpms to work...

Are you saying it just needs one jump to 3700, and then it works? or you have to hold it at 3700 to work?

 

Your either missing the batt voltage to the small plug on the rear of the alternator or the regulator inside is toast. It's the white wire with a blue stripe that needs to see batt voltage.

 

yeah it just needs one jump to 3700 and then it works. but i'm hoping its just the regulator inside... wouldn't surprise me, it's a reman alternator. i guess we'll just see what happens when i put the fd alt in... well i still need to get it....

 

,

 

obviously if he has to rev it 3700 its not ok, correct me if in wrong but is it that hard to check all wire connections leading to and from the alt, check the belt tension, and if need be go to autozone and use one of there nifty inaccurate alt testing machines.

if all fails the alt is most likely a paper weight.

how hard is this to figure out on your own??????

the FD alt comment was thrown in for the redundancy of the original post, why trouble your self about something you plan on replacing?

 

well thats the thing, i have tested it :P it tests ok if it's been excited, and it tests as bad if it hasn't. and i'm just wondering if it's an internal problem with the alt, or the wiring itself.... thats why i threw the fd alt thing in there

 

well take option C and buy an new alt, **** like that just goes bad sometimes.

 

Did you check the wire I mentioned to see if it had batt pwr or not? If not, then the *new* alternator isn't going to fair very well either.

 

^ that plug is a tricky one. i had a buddy pull mine out as a joke...... needless to say it wasent very funny when i pulled out on the road with a loopy idle and very flimsy power band

 

been busy, finally found time to check voltages at terminals:

Terminal - Volts Key Off - Spec Key Off - Volts Key On - Spec Key On - Volts @ Idle - Spec @ Idle
B - 12 - 12 - 12 - 12 - 14 - 14
L - 0 - 0 - 12 - 1 - 14 - 14
S - 12 - 12 - 12 - 12 - 14 - 14

could the L terminal be seeing 12v when it's supposed to be seeing 1 because the regulator's shot?

 

My buddy and I have this same problem as well... hummm

 

Intermittent problems like this sounds like bad alternator electronics (rectifier or regulator). Getting your alt tested is free at most auto stores, and pulling the alt is easy. If it's bad, save your warranty on the replacement alt, because short lived replacement alts are common.

 

With the key to ON and engine OFF, the L terminal should show 1-3vdc, closer to three volts. That three volts would be the excitation voltage for the field from the regulator. IF that is not there, then the regulator is kaput imho. The free, online FSM, Engine Electrical section says the same.

That 1-3vdc would be with all the plugs on the alternator and backprobing the L and S terminals. Gotta have the small plug connected to the alternator.

 

That's a jpg of a series four alternator, but the same applies for a series five. The plug is just in a different configuration.

 

Mine has the same issue- Its the voltage regulator. I had mine rebuilt several months ago with a new regulator. E-fans really add quite a bit of load on the current system.

 

thats the thing. of course it tests good if it's putting out amperage once i've hit the initial 3700 rpm. but i tests bad if i haven't done that.

and HAILERS, yeah those figures were from me backprobing the terminals (plug on). i'm pretty sure the regulator is shot as well, i have an fd alt coming soon, so then it'll all be sorted out