2.3L of fun

[funwithmonkeys]

alternator case to positive on the alternator is 15.4 and alternator cast to reference line is 15.4. I have a main ground point in the dash with a line running from it back to the battery. I sat there with the neg probe clamped to the alternator and checked everywhere that I could get to easily and they all read the same. I repeated it with the neg probe clamped to the negative battery terminal and got the same. Everything was within 0.1V. I will check out that video in the morning and see if I can find anything else.

[510rob]

Does the battery have proper electrolyte concentration, or has it been boiled dry?

[funwithmonkeys]

Ok so I have spent another 8 hours diddling this thing and no luck.
Rob yes the battery is good. It has a total of 20 min of testing time on it. 2 to 5 min of run time each time. I got the alternator tested at Dundee and they got 14.3V so I have confirmed it is good. I went through and disconnected, checked and cleaned all contacts in the positive and negative side of the wiring. There was one connector that was iffy so I just replaced it.
Next I ran a set of jumper cables to the battery from my truck from the alternator with everything else in the car disconnected from the alternator.
Everything gives me 15.4V
Could something in the car be causing interference with the Voltage Regulator in the Alternator causing it to put out too much? The coils are about 8 to 10" above it. I disconnected everything net necessary to run the car. That is the only thing left I can think of.

[Cmac]

Just a thought does the generator light on the dash turn on when you turn the key to the first position? One of my failures was not having a proper ground from the alternator.

[funwithmonkeys]

Yes it does. I have grounded this thing so good now it could take a lightning strike.

[RMS]

could there be resistance to the dummy light via the ig sw ? or the bulb its self ? I would be tempted to plug a 8ohm resistor directly into the T plug on the alt and see what I get.

I got a ig sw for you if thats the case

[bertvorgon]

Did you change ANYTHING on the car over the past year that may cause the alt to think the system is seeing this HUGE drain so it tries to put out as though the battery needs the top up.

Any weird ground in the LED headlights...something like that.

I once, on the way to Knox, had a short and the alternator tied to make up, it hit 15 Volts on my gauge and then snapped the 17 volt fuse in my Escort radar detector.

Sorry your having that problem.

[funwithmonkeys]

Thanks guys. When the motor was put in the car Andy put the previous version of this alternator in. It would bootstrap by itself above 2500 rpm. I always had just a jumper from the alternator output to the sense pin and then the idiot light hooked up. It all worked as expected. When the alternator died I put in the newer version of it and have had constant problems since. The first one lasted 1000km then went to 15.4. Every one after has put out 15.4. Yes I know it sounds like something in the car.
Nothing changed in the car except a few cosmetic bits inside and all the testing was done with all the fuses pulled from the stock fuse box to eliminate any issues in that wiring. I only had the EFI box powered and only the necessary fuses to rum the car installed.
Yesterday I replaced all the wiring between the alternator and the battery with new 1 guage cable. Ground down all the ground points with a wire wheel and put it all back together.
No change. After a period of cursing I ordered a 90amp 1 wire alternator. It actually costs less than the one I have in now. From the measurements it should bolt right in and has much less that can cause it issues. Fingers crossed.

[icehouse]

Just run a 50' battery cable, the voltage drop will sort out the issue. You will have nicer spark and you won't over charge your battery. I'm sure Rob would agree it's the best solution.

[510rob]

Just run a 50' battery cable, the voltage drop will sort out the issue. You will have nicer spark and you won't over charge your battery. I'm sure Rob would agree it's the best solution.

There is something else going on here. I am beginning to wonder about this mystical 15.4V alternator being one of the newer style units that needs a control line from the OEM ECU, like a lot of newer cars use.

I think Norm should put in an older 'early style' alternator, like the original one that used to work.

[funwithmonkeys]

Ya they don't make it. This is the one that is listed for the KA from the 1990 240sx. I have also tried a 100amp one from a newer nissan. I have spent enough hours on it now. My car hasn't been this far apart since I did the injection. There is a 1 wire on the way.

[Byron510]

Gawd, does this bring back memories of me pulling my hair out. i just hope it doesn't take you the years it took me to find my problem!
I'm feeling for ya.
Let us know how the one wire works out.
Byron

[funwithmonkeys]

Thanks Byron. I will. It should be here this week.

[funwithmonkeys]

Well I got to putting in the 1 wire alternator yesterday. I am getting a rock steady 14.8V. I went through after that and put new connectors on all the ground straps and wire brushed all the points they bolt to. I even cleaned up the main bolt that holds the Alternator on place and ran a wire brush through the hole it goes through. I went ahead and ran the car with nothing but an external battery hooked to the alternator with new 5' battery cables and the car running off of the battery in the trunk and it was 14.8V. Hopefully this will be good enough. I'm out of ideas now. There is nothing else to replace and no other ground points to look at.

[bertvorgon]

That is very much what I get, given the gauge's ability to fine tune the decimal point.

mine is rock steady too, when I turn on headlights it drops a for second, as the load goes up, and then back.

Glad you got it working!