alt not charging
 

new engine fitted runs well but not charging alt. changed alt and still not charging.
Sons car called RAC (cos wiring ain't my thing) he said something about a agitator wire (WTF) any ideas anyone on y its not charging?
pointers be good.
he mentioned wires from alt to loom but goes via ign barrell and no power coming through the 2 wires into the alt pug....FFS everything else works..
help please

Not sure if I can help or not, but please share some more info...

1. What motor are you using? Is there a computer involved?
2. Are you using the Miata wiring harness or the engine harness from the transplant?
3. Guessing it's not a single wire alternator? Picture / telling us the above will help figure that out.

Can you take a few pictures? of back of alternator and how you have things currently wired up to it?

A couple things to check right now.
1. Have you checked the fuse or fusible link if you have one?
2. Is the alternator grounded? (sounds stupid, but if you powder coated or painted the bracket, it might not be grounded.)

1.8 2002 retro turbo aftermarket ecu
Standard wiring (from the car)
3 wire alt (1 main and 2 in a plug)

Main feed to the nut and bolt at the back of the alt
1 plug with 2 wires in the side.

Was told the exciter wire was not live this feeds back to the igniton and ecu -correct?

I'm about 99% sure your problem is that you have a 2002 with an aftermarket ECU. The alternator on NB Miatas are controlled by the ECU and most aftermarket ECUs can't control the alternator. Most guys "fix" this issue by getting an alternator from a 1.8 NA Miata. The 1.8 NA Miata's have an internal voltage regulator that controls the alternator. I don't know if you have to wire up anything differently, but a quick google search on this problem should get you the info you need. If you search on MiataTurbo, I'm sure they have info. A lot of NB Miata guys run a megasquirt with their turbo Miata and have this issue.

Good Luck

https://cimg1.ibsrv.net/gimg/www.v8m...8b6c1422bf.jpg
Add a small bulb or resistor.