About to start my R3 install on my FD, and while wandering through NSP and assigning things I noticed that ol Haltech seems to have defaulted their OMP config to a 6 wire setup in all their S2/S3 basemaps. Interestingly, this allows you to use DPOs to drive the OMP instead of HBOs.

Historically I've removed the +12v feeds on the OMP and then just ran them w/ 4 HBOs. This new method is enticing me because I'd rather burn up some of these extra DPOs I've got, and save HBOs for things like drive by wire, etc.

Has anyone messed with it recently? Is there a downside to doing it the new way that I just can't think of?

 

Was told by an EE years ago when we were working with Syvecs to implement OMP control with their ECU that the 4 wire scheme is preferred. It’s been a long time and I’d have to dig in the way back to find the reason why. Believe I was told 4 wire creates
ore torque on the motor and lowers response time. I still wire them this way, if I have the outputs. Since Mazda wired them using 6 wires, I doubt it’s a bad thing. If you wire it as a 6 wire, you can use the new presets in the software. If you wire it as a 4 wire, you’ll need to set it up as Custom, which is not a big deal.

 

I'm curious about this too. On other ECUs, the OMP could be 4 wire DPO + AVI for feedback instead of HBOs in Haltech's diagrams and harnesses for Nexus ECUs. I'd like to save the HBOs for DBW and electronic wastegate use. Using HBOs for OMP will push need for a PD16 as well.

 

Then use DPO, or extra injection or ignition outputs with the 12V+ source.