AlexMeelo

Hi all,
I've been I've been running alternator issues with my 1990 1.6L turbo build. For context, It's a built big nose 1.6L with a FM turbo kit. Has an ATI damper (so of course an alternator/ water pump pulley conversion to 1.8L pulleys). Running MS3 PNP and an innovate MTXL-plus wideband. All new everything including alternator. Before the build, it was a stock engine 1.6L Miata that was used as a street/ track car and didn't kill alternators...

The problem at hand:
The car keeps killing alternators. I've been through 4 now (Thank god for warranties). The first and second ones I thought were just bad alternators, but the issue persisted. The charge light would begin to flicker on and off rapidly under load usually regardless of RPM, Throttle position or acceleration or deceleration. The alternators would then start to overcharge little by little climbing to about 16 volts and the internal regulators would bust after a bit. (I keep an eye on voltage using a car plug in volt meter and tested it along side of a multi-meter to ensure it was giving accurate readings). I got my local auto parts store to test the battery and they said all was good and strong. Checked my grounds and cleaned every grounding surface. It totally slipped my mind that wrinkle paint wouldn't be a good ground. Sanded down every ground to ensure good ground contacts (Block to firewall, intake manifold grounds, PPF ground, battery ground, etc...) The belt tension was also checked each time and tight within spec according to forums. I've tried both brand new alternators and re-manufactured alternators. both 1.6 (just swapping the pulley) and 1.8 alternators. The current alternator has lasted the longest since cleaning up the grounds but the charge light is beginning to flicker again, especially on spirited drives. The only difference this time is the voltage readings I'm getting are pretty normal for a new alternator (around 13.8V-14.4V). The charge light will only flicker after being driven for about 20-30 mins but the voltage reading remains around 13.8V-14.4V. I've even changed out the gauge cluster thinking maybe It's an issue with that but same result.

Am I missing something? It's been driving me crazy this whole summer. I'm stumped. I'm hoping its something simple that I'm missing? A friend told me that my issue could be that I soldered in connections for my electronic boost controller and my wideband but I'm not so sure about that. Hoping its not a whole wiring harness... Any insight or tips would be greatly appreciated!!
Thanks for the read.

LeoNA

I have had a similar issue with my 91, FM1, MS3Pro. I think the cause is from the parasitic draw of the MS3 or some other component. The way I have been able to prevent losing alternators is by using a battery tender whenever the car is not in use.