How to MegaSquirt Your Mazda Miata

MSPNP ALERT!

Check out our out‑of‑the‑box plug‑and‑play ECU for 1990–2005 Mazda Miata & MazdaSpeed. It plugs into the factory harness, typical install is about an hour, and it’s ready to run with no wiring changes.
Link: MSPNP-Pro Mazda Miata

Applications

  • 1990–1997 Mazda Miata (NA)

  • Later models if swapping in a 1990–1997 CAS

Level of control: Full standalone EMS — Fuel and Ignition Control


Tach Input Background: Miata CAS

The 1990–1997 Miata uses a Crank Angle Sensor (CAS) with two rings of trigger holes:

  • Outer ring (CKP): Four slits, provides RPM signal.

  • Inner ring (CMP): Two slits, provides top dead center signal.

Some later models used a Hall effect CAS, but the signals are electrically identical.

MS2 Setup

Board Pinouts:

  • CKP → DB37 pin 24

  • CMP → DB37 pin 5 (or DB15 pin 7 on V3.57)

  • Spark A → DB37 pin 36

  • Spark B → DB37 pin 6 (or DB15 pin 10 on V3.57)

  • V3.0: TachSelect → VRIN, TSEL → VROUTINV, CMP via JS10 → SPR3.

  • V3.57: JP1 = 1–2, J1 = 5–6, CMP via JS10 → PAD7.

  • Add pullups: CKP (5V), CMP (5V with 1K + 470Ω).

  • Add cap mod: 0.01 µF capacitor from JS10 → ground.

TunerStudio Settings:

  • Spark mode: 4G63

  • Input capture: Falling edge

  • Spark output: Going Low (stock ignitor) / Going High (BIP373)

  • Number of coils: Wasted Spark


MS3 with MS3X

Board Pinouts:

  • V3.0: TachSelect → VRIN, TSEL → VROUT.

  • V3.57: JP1 = 1–2, J1 = 3–4.

  • CMP pullup: JP7 on MS3X.

  • CKP pullup: external 1K resistor or R57 internal.

TunerStudio Settings:

  • Spark mode: 4G63

  • Input capture: Rising edge

  • Spark output: Going High

  • Number of coils: Wasted Spark

  • Spark hardware: MS3X Spark

  • Cam input: MS3X Cam In


Safety Note

Always disconnect coils/ignitors when flashing firmware. The MS will hold lines high during flashing, risking coil or ignitor damage. Reconnect only after flashing and reloading your tune.