Why is that so strange? Overvoltage protection shuts MS down, TunerStudio loses connection and gets confused.

Waaait a second. I overlooked the word "Mechanical". So, is there a relay of some sort inside the MS that shuts it down? If so, that certainly explains all the clicking I'm hearing. If not, what's the shutdown mechanism?

It's not a relay, but it also is not anything you can adjust or tune: https://en.wikipedia.org/wiki/Varistor

Thanks, Matt (brings back my EE education from 25 years ago :) ). I heard clicking and thought it was coming from MS, so was assuming some sort of a relay. It could have been fuel pump relay clicking, I assume, depending on what MS was telling it to do as it was shutting down from overvoltage. I don't think there's anything else nearby there under NB dash?

the clicking is the fuel pump relay turning off when the MS shuts down.

After replacing what looked like a little iffy R3, the MS2 still appears pretty dead with the same symptoms - it now doesn't really connect to Tunerstudio and complains about mismatch in project. Interestingly, with the key in the on position today I heard some faint whirring noise under the dash (??). Also, was actually able to have a relay click on and off by moving the harness a bit. Re-rang the harness again, looked at DB37 connectors, don't see anything obviously loose or cold-soldered.

So, is there anyone or any service that can test this MS2 and fix it? The car had to run on stock ECU today and, of course, was on the limiter a bunch of times at autocross. I'm willing to pay someone, of course, to do this, but have no idea who to turn to. Please help.

Just a quick follow up. The MS2 went to Peter Florance of PFTuning. Peter found fried components internally, replaced, checked. The MS2 is now back in the car and running.

Not sure what killed it. Either the constant vibration and general violence of a dedicated CSP car or the problems with starter that I've experienced prior to MS2 crapping out. Either way, just wanted to update if anybody has similar symptoms in the future.

Any idea what exactly was fried?

My car has fully the same problem...I kill my front light bulbs in every month once...it means there is a real voltage peak, not just an MS calibration problem, I think.

ECU is from Reverant, red boxed, built at year end of 2013. Perfect stuff except of this problem with the alternator regulation issue.

I logged the same problem with a very-very similar ECU in my friend's car as well. (1.6 MK2.5, SC)

Lucky to find this topic, I already have a rebuild alternator and also a starter motor, bought a new battery...problem not solved yet.

Based on the solution proposed above, I let control my ECU with a local specialist, mybe we will use Westfield MX-5's new alternator control board.

Keep fighting! :-)