ohayou88

iTrader: (7)

The car is a S4TII and have voltage drop problems. When I first start the car I get around 14.3-14.4 volts. but as the rpms drop so does the voltage and I get around 13.8 at idle and 14.0 while in gear. But once I turn on my headlights the max I can get is around 13.7 and voltage drops as I step on the brakes or turn on the heater or rear defroster.

I have not hacked in electronics that take up a massive drain just a small set of after market fog lights that runs on a switch.

So I have a new battery got a reman alternator (autolite), and have done the grounding kit in the archived section. But still have voltage drops. And I had the alternator tested to see if the voltage regulator was bad but its good. So Im out of ideas now.

The best Idea i can come up with is that the s4 alternator just does not have enough amps and need to go to a S5 altenator or an FD one. But before I do that I want to see is there anything else i can do.

dennis blackstone

check my post i added a write up on a fd install for $30 of ebay and $45 for banzaitoyota pulley fc-fd conversion ...my post is under (how many people have fixed flooding issues and what method worked ) i put it under there even though it has nothing to do with flooding ...i put alot of projects under that thread ... but let me tell you the fd alternator by far is a good investment i get 14.7 at idle with lights and wipers and heater 14.5 .. but i beefed up the terminals its incredible ...also my post has pics

ohayou88

iTrader: (7)

I looked at it. But Im getting confused on how to wire it up.

So S5 and FD plug is the same I assume. The Red wire attached to the blue and white wire run directly the battery. And the black and white wire you use like a spade and plug it into the stock plug???

dennis blackstone

you got it remember the fd alt will have the blue and white wire going straight to the battery the top terminal with the 12mm nut will go straight to the battery ...the black and white wire from the fd alt plug will go to the dash check the fsm its very easy any problems let me know ....i have an efan on my 7 now i dont have to worry about a voltage drop good luck fd alt is the best but yes the fd and the s5 are the same i had to modify mine for a s4 so yours is plug and play if i remeber correctly

Icemark

What is the amperage output of the alt you already have.

Sounds like maybe you bought a rebuilt alt, and not a remanufactured one.

Rebuilt alts often show exactly the same symptoms as you describe.

I would bet the alt is not putting out decent power.

dennis blackstone

i second that ,remans have been a problem for me ..i ended up with a fd 14.7 all day 14.5 when i use something

ohayou88

iTrader: (7)

It says its reman on the website and its 70amps.

My TII is an S4 so i would have to do the same as you.

Icemark

But what is it really?

What did it show up at when they tested it?

ohayou88

iTrader: (7)

the guy said its in spec at 70amps which I highly doubt now. I asked if i could get a print out or see the actually numbers and he gave some excuses about liability etc.

NZConvertible

I can see why... Here are the schematics for S4 and S5 alternator wiring, and putting an FD or S5 alternator on an S4.

Alternator schematics: https://www.rx7club.com/attachment.p...hmentid=199213
Alternator pin-outs: https://www.rx7club.com/attachment.p...hmentid=170065

Swapping an S5/FD alternator plug onto the S4 wires is a much better idea than using two spade connectors.

ohayou88

iTrader: (7)

im starting to understand I'll study it some more when i have time. but thanks NZConvertible that clears it up a little more.

Someone should do a good writeup that can go into the archives.