LS2 coil settings with microsquirt

[Martin Wagner]

I have been racing a 1990 Mazda Miata for several years using a microsquirt V2 with a 18-1 crank wheel and the OEM ignition module and coils. I am trying to replace the OEM ignition module and coil pack with GM LS2 truck coils. The only setting in the Tuner Studio ignition settings that seemed to need to be changed was the Spark Output setting in the base ignition page. The OEM was set to Going High (Inverted) and the LS2 description indicated to me that the LS2 coils should be Going Low (Normal). When I tried to start the car with the LS2 coils set Going Low (Normal), the timing was very retarded (ATDC instead of BTDC). Changing the LS2 Spark Output setting back to Going High (Inverted) gave correct timing.

Questions.
1) Did I misread the LS2 document about what the correct control signal level should be?
2) Is the Tuner Studio Spark Output settings reversed for a V2 microsquirt?
3) Should the Spark Output be set going high or low?

I am using Tuner Studio v2.0.6 and B&G v3.780.

Thanks for the help,
Marty

[Matt Cramer]

What MicroSquirt version are you using? V3.0s should be set to going high / inverted.

[Martin Wagner]

It's a V2.0 unit. The 2 jumpers (JP5 & JP6) are from pin 2 (center) to pin 3 (farthest from case). Is this correct to bypass the high current output drivers? Does the jumper position change the high/low setting?

Thanks,
Marty

[Matt Cramer]

Yes, that would also use Going High. I think the Going Low was intended for using the high current drivers with a pull up. That would have inverted the signal.