My plan is to do the second opto isolator like you guys did. If that fails, I'll swap CAS, If that fails I have exhausted all my options other than swapping out my ms1 or changing to a trigger wheel.

Wanted to add to this thread. I have suffered from this issue on my fathers 95 from day 1.

I have built the optoisolator circuit to no avail.

It is an extremely long story but when the car had MS2 on it, it had no issues. After I converted to MS1 this is when the symptoms showed themselves. I feel the optoisolator circuit did indeed "help", but not cure the issue.

Seriously though, with how easy it truly is to change to MS2, it doesn't make much sense to continue to run MS1. Unless you already have a spare CAS, spend the money on MS2 and upgrade what you have.

While that might work, it's more of a workaround than a fix. To me, I don't need an MS2 just yet, so I'm not too eager to upgrade.

I've considered going MS2. what all is needed to convert?

swap in the daughterboard and redo the inputs?

Bringing this back.

I cleaned all grounds and ran new one to the ecu from head.
Upgraded to Toyota COP setup.

Problem still persists, though it seemed like it was not as severe/often, though I only drove it today.

So I suppose the only thing left is the CAS?

CAS or upgrade to MS2. I may upgrade to MS2 with my income tax refund. I'll be sure to report back if I do.

Is the CAS known to go bad at all? (i haven't really seen much info on them going bad)

Is there anything to clean in them?

Did you try Joe's circuit?

https://www.miataturbo.net/attachmen...-schematic-gif

No I have not, I did try the 2nd opto circuit posted in the 1st page.

I tried Joe's circuit and the car didnt start, but I probably messed something up. That was 2 years ago and I just swapped everything back over immediately.

I am going MS2 in the spring, using the standard inputs. If I have issues after that I will continue investigating.

I wonder if switching to a trigger wheel setup would fix this

I think that is what Joe ended up doing. For me that is an ugly option as I need to be able to swap back to the stock ECU easily for OBD2 emissions here in CT. I don't want to have a secondary harness and a bunch of shit to change.

It was, back on my first Miata and my first MS1. I now know more than I did then, and I would not recommend this as a fix for a finicky CAS.

In my case, the CAS worked fine on the stock ECU, but not the MS. That alone tells you that the MS was the problem, but I really wanted to build something on my new lathe, do I solved the problem the extremely hard way.

I would use a 2000 protege 36 to 1 wheel and fit an NB (99+) crank sensor (do those bolt straight onto 1.6 oil pump?)

So I don't think it would be too hard nor crazy expensive

Swapped the CAS for another one I got with a used engine. Still no change. Also soaked the board in alcohol to clean all the flux off (i never did the first time around as it was supposedly no clean flux wire). Still no change. I'm at a a loss here.

It sucks this didn't work out for you. It worked out great for the 2 MS2's I tried it on. Maybe having MS2 made the difference...

Switched to 36-1 and a Hall sensor and have more noise than before.

If I rev the engine and hold it around 5k it will have RPM spikes in logs to 10k.

Activates rev limited/retard resulting in flames lol.

Installed a shielded wire on the sensor, improved things but still spikes.

So basically I've tried:
Switched to COPs to eliminate coils/igniter
Switched to a new CAS
Built second opto isolator
Cleaned the board
Added more grounds/cleaned existing
Switched to 36-1 with a Hall sensor

So the only thing left original/unchanged is the MS1.

Will an MS2 card do it or is something else inside my MS messed up? Ahhh such a headache

edit:
said fuck it, summer is near, ordered MS2 daughter board

I hope upgrading to MS2 works for you, I know from experience how annoying it is to drive acting up like that.

Any luck, Kero? I just freed up some money and am considering moving to an MS2

Not that it would make a difference at this point but the capacitor you have show is .1uF, but looks like you ordered a 399-4326-nd which is 10,000PF or .01uF. .01uF is also what's shown in the msextra docs. I'm looking to cure the sync problem myself :)