I'm installing an 04 Mazdaspeed Miata drivetrain into my 99 Miata, with a MS3X running it. The 99's coils got their 12v+ directly from the main engine relay and had no condenser; the 04 MSM coils got their 12v+ from pin 4S on the stock ECU and had a small condenser bridged onto the circuit.

I'm using the stock 99 under hood harness with a DIYBOB to patch in to the MS3X. I've replaced the 99 coil connectors with the ones that fit the 04 MSM coils, connecting 12v+ to 12v+, ground to ground, and the logic/triggers to the coil 1 and 2 on the MS3X.

Do I need to splice the condenser back onto the 12v+ feed, or can I ditch it? In other words, is there anything specifically different about the MSM coils that requires its presence, or was it just there because they had been getting their 12v+ from the MSM ECU?

Thanks in advance-

 

your 99 has one connected somewhere...

 

I've checked the 99 wiring diagram thoroughly, and there isn't one, unless perhaps it was integrated (internally) in the coils themselves.. (?)

At any rate, should I splice it onto the 04 coils 12v+ feed?

 

Oh, one quick correction to my original post- the 12v+ feed on the 04 coils did come from the main power relay, fed the coils *and* was connected to the MSM ECU, which I guess was monitoring the voltage or something.. (I don't have a pin chart for the 04 ECU telling me it's function. That same black-white 12v+ line also supplied voltage to the O2 sensors..