Megasquirt PnP into Motronic 1.0 (it works)

[12valves]

No further need for speculation about whether the stock speed/reference sensors could be used to drive MS. I just proved that it works.

I took my MS1 + Zeal Engineering dual-VR board, and wired it for the second sensor (I was using only one previously on my M20 w/ 60-2 wheel). Plugged in the 35-pin connector, IAT, and vacuum line, and my shark started right up and idled at 2000RPM (lulz)

I had eyeballed the old M20 parts sitting around my garage to try to figure out what the triggle angle would be. Using my powers of assumption, I made up some numbers that I thought would work for the M30. After removing the water pump pulley so I could find the darn TDC mark I checked it with a timing light. Turns out I was off by 22 degrees. After fixing that, it runs half-way decent with recycled M20 VE/spark tables.

The M30 flywheel has 116 teeth. The only problem with this is that it isn't divisible by 3. The MS1 spark timing algorithm depends on having 3 trigger points that are evenly spaced 120 degrees apart for an inline-six. With 116 teeth there are no such points, so I am using the closest possible teeth. This introduces an error in the spark timing of up to 1.5 degrees. This is not too bad and it could be fixed with a fudge factor in the code.

The trigger angles ended up being pretty close to what I was using with the front-mounted 60-2 wheel on the M20. In fact, maybe it was designed to be the same, but it will vary a bit depending on whether the electronics and software are setup to trigger on rising or falling edges. Since the flywheel is not a missing-tooth wheel, it can work with either polarity.

Wheel decoder settings:
base teeth: 116
2nd trigger enable: yes
2nd trigger active edge: rising edge
2nd trigger missing teeth: none
Trig Pos A: 13
Trig return Pos A: 28
Trig Pos B: 52
Trig return Pos B: 67
Trig Pos C: 90
Trig return Pos C: 106

Spark settings:
Trigger angle: 66

Cranking timing: trigger return
Cranking advance angle: 12

Note that the S14 has the same flywheel sensors and number of teeth. Since it only needs 2 sparks per rev instead of 3, there would be no issues. Same goes for an M10, if someone happened to fit a Getrag 260/265 onto one.

On the M20 flywheel, I count 137 teeth, which is again not ideal but it could most likely run.

[AlpinaE24]

With the price and availability of B35 wheels why would anyone even go this route?

[12valves]

Corrections: I changed the trigger angle, it should have been 66 not 60.

I should also note that the MS1 Extra code I am running uses the difference between two trigger intervals to predict the length of a future interval (to compensate for engine accelerating or decelerating). Having uneven trigger spacing breaks this, and introduces an additional error in spark timing.

edit: since MS2 Extra uses "every tooth" for timing, I wonder if it could handle this setup as-is without any timing problems.

edit2: actually no, because according to this thread the number of teeth has to divide 360 degrees: http://forum.miata.net/vb/archive/index ... 79044.html

[//grecko//]

Nice find. Sometime, the damper can be pita to remove.

[12valves]

Updated: latest firmware, config, and tune after dyno run. I should also note that I'm running non-stock injectors, I think they are a slightly lower flow rate around 21lbs/hr.
http://www.hyakushiki.net/motronic/m30-3c.7z

[briansmith]

Thanks for sharing this.
I've got no use for it at the moment, but might sometime later.

[cscracker]

Sorry to dig up an old thread, but I'm trying to do exactly this on my 533i. I'm using a Microsquirt and I've got everything wired up. The problem is, I can't figure out how to actually set these custom tooth positions anywhere in Tunerstudio. Does anyone know how to do that? Is it no longer possible with the current software?