Setup and wiring notes for the 1999–2000 MX-5 (NB) running a DigiTune ME221 or ME442 ECU.
Clutch switch pin bridge (optional)
Gen1 ME221 ECUs, and Gen2 ME221/ME442 ECUs prior to the revision 1.5 base board (introduced in early 2021), have the clutch input on the wrong pin. The simplest way to correct this is to add a wire bridge on the ECU. An example of this modification is the shorter yellow wire in the photo below.
Wideband AFR gauge/controller
ME442 ECUs have an inbuilt wideband controller, so they do not require an additional gauge or controller. The ME221 does not have an inbuilt wideband controller, so an external wideband gauge is required. I recommend the AEM X-Series wideband AFR gauge:
AEM X-Series UEGO wideband sensor and gauge
Or an AEM wideband controller without a gauge, if preferred:
AEM X-Series wideband controller
Recommended wiring:
| AEM wire | Connection |
|---|---|
| Red | 12V switched live |
| Black | Chassis |
| White | Blue wire in the OEM narrowband lambda harness |
| Brown | Black wire with a red stripe in the OEM narrowband lambda harness |