dbragg

iTrader: (7)

So, I have been messing with this issue for far too long, and I am tired of getting nowhere with it. Thus, I turn to the forum for expert knowledge

Background on car:

I have owned it since 2007. My buddy was the previous owner, and bought it completely stock from a local dealership who got it from the original owner. Before I bought it he did some modifying to the car. He installed an electric dizzy, swapped the carbs, and cleaned up the engine bay wiring. He drove it a lot after doing these mods, and didn't have any known issues. That being said, there may be some issues with the dizzy wiring since I have to use the trailing for my tach signal, and it's supposed to be the leading apparently. I had some electrical issues about a year ago that lead to me to believe that the alternator was going out on me. So, I picked up a used S5 100A alternator off the forum. I installed it via the info on here; did the two jumper wires on the voltage regulator plug, ran the L terminal to the stock WB wire, and the S terminal to the positive battery cable. Easy enough, or so you'd think.

My electrical system seems to be getting the best of me. With the car at idle I am getting a voltage of 11V-18V at the battery, and 19V - blank screen(don't know what that means) from the battery negative to alternator B terminal. There is no change when I turn all these on together: taurus e-fan, high beams, and hazards. The voltage isn't constant either, it surges, and doesn't seem to follow any pattern.

So I decided to test the alternator. I took it to a local auto parts store and it seemed to test fine. I even went to a buddies house and we swapped the alternator from an FD, looked identical to my S5 alternator(amperage and all), onto my car to test it. Before we did the swap I tested the alternator on the FD, using my battery because his was dead, and it held steady around 14V. We put it on my car and it did the same as mine, surged and was high.

Also, I have used three different batteries, without any change, and one of which was used to conduct the FD test. Kind of eliminates that.

The car had stock battery cables, so I figured maybe it was time for them to go. So I built all new battery cables. I ran a ground straight to the starter bolt, and one from the front rotor housing to the chasis. I also cleaned up the ground at the hatch. Did the tests again, no change. I can't seem to find the ground at the ignition switch. Anyone have a picture of this?


So, I am kind of clueless at this point. Any ideas?

Siraniko

iTrader: (13)

How do you know that it is over charging or whatever? Do you have an aftermarket volt-meter? if so, where is it connected.

Years ago, I had similar issues in my RX-3s after conversion to FC S5 alternator but it went away after I upgraded the "B" terminal wire to fuse box to 4 gauge wire (you can also use lawnmower 8 gauge if you must) along with additional ground wire from block to battery.

There are only a few differences between your SA and my RX-3s: I ran my own ignition wires (coil to igniter) and I removed the factory wires to alternator, thus voltage regulator eliminated. Battery wires replaced with 0 gauge + 80amps GLC engine fuse block (similar to FC).

dbragg

iTrader: (7)

Mel,

From my readings of my DMM voltmeter it is showing a very sporadic voltage at the battery and at the B terminal while the engine is running. No consistency at all. It ranges from as low as 7V-19V+. At the B terminal it even makes the DMM not show a reading, just a 1*.**(* are blanks), most of the time. The DMM is rated to a max voltage of 75v, I believe, so I don't think it's going higher than that, just not sure why it's blank.

Yesterday, just before creating this thread, I swapped the stock B terminal wire back onto the alt. Before that I had created my own B terminal wire, from the FC B terminal harness that came with the alt, and had it ran straight to the FC fuse block main fuse, which was originally 80A but I switched to a 100A fuse. There was no difference with either setup. I'm not sure of the gauge of the wire, but I have a good amount of random large gauge wire, so I will try it swapping it out with something else and see if it changes anything.

I don't have a ground from the block to the battery, but I have one from the battery to the starter bolt and from the block to the frame. I tried using jumper cables as a ground from the alt housing and block to the strut tower(RB strut tower mounts), but it didn't change anything.

I mean, it's such weird sporadic readings that I even suspected my DMM of being faulty, but it's spot on whenever I test any other vehicles.

If I can't get any ideas from here, then I guess my only option is to strip down the wiring harness and go through the whole engine bay harness making sure everything is spot on. I was just hoping for a faster resolution. I am also going to try to find another good FC/FD alt locally to assist with my testing. Even though I kind of already eliminated that variable, but just in case.

Could the ignition switch be my culprit? I haven't had any other issues with the switch though.

I will try to do more testing this week around school and ROTC and post any new results.

Thanks for the advice.

Siraniko

iTrader: (13)

unlike the S4, in lieu of ignition wire, there is a sensing wire for S5-FD alternators to start charging, typically engine must be reving above 2K rpm. The only wires you should have are the "B" terminal and the bypass or sensing wire. On my RX-3s, I relocated the factory "B" terminal wire (IIRC white/red) to the engine fuse block (80amps) since I ran a 4 gauge from B to fuse block.

dbragg

iTrader: (7)

I am finally back on trying to fix this.

After rewiring some things I no longer have a surging idle. Like stated above, the alternator doesn't charge until excited by lightly revving the motor. Once it is excited it now holds a consistent 16V. While using jumper cables to ground the alternator to the chasis the voltage drops to 15.98, which I am not sure means anything. I swapped in an S6 alternator, of unknown condition, and had the exact same results. So I am certain it is wiring.

I will be doing as Mel suggested; running the B terminal to my FC fuse block and an additional ground wire from the battery to the engine.

dbragg

iTrader: (7)

Well, I finally solved this today, and it was a tricky problem.

I ditched all of the stuff for the "like stock" alternator swap and just went with simplified install route. A voltmeter isn't a necessity at this time.

As Wacky suggested, I upgraded to a 4 gauge wire from the FD alternator B terminal, ran a jumper wire with fuse from the S to B terminal, and left the L terminal empty. The one difference, I didn't run the 4 gauge wire from the B terminal to my FC fuse box because it wouldn't fit, so I ran it straight to the battery. I may change this if/when I install an additional FC fuse block.

I had previously built and installed all new battery cables using 2 gauge copper wire. One ground ran from the battery to the stock location at the transmission, and the other ran from the top of the engine to the strut tower. I rerouted the one from the top of the engine to go directly to the battery. I will be adding an additional cable from the top of the engine to the strut tower.

During all of this I also checked wiring work from the previous owner and reran better wires to my MSD boxes.

With all of this installed I was sure it would fix the problem, and it kind of did, or made it easier to find. Upon installing everything when the motor ran there was a very apparent noise coming from the dizzy. This noise was eliminated when I disengage the trailing ignition. Thought it must be dizzy cap fitment, so I pulled everything off and reinstalled making certain it was correct, and the problem was still there.

To wrap it up more quickly, inevitably, I determined that there were two things at play. The ignition was wired incorrectly, leading was being controlled by trailing " "ignitor" and had been this way since I owned the car over 5 years ago. That would explain why neither the previous owner or I could get the alternator to read correctly. Finally, the source for my surging high voltage, was a short in the distributor with the trailing wiring. I bought the distributor from someone who had raced it and modified it to eliminate the ignitors and use to trigger MSD boxes. Well, apparently over time a short was created, hence the erratic high voltage and noise from dizzy. I verified this by testing the voltage with the trailing ignition functioning and disengaged.

So now my problem is solved. I will be ditching the trailing ignition as a whole, utilizing my second MSD box elsewhere, and I hope this information helps anyone else facing a similar challenge in the future.