After I finished rewiring the Cobra drag car’s trunk, I found myself needing to pull a fuse to do a test and not remembering which fuse was for what. Having all the fuses and relays in one panel was a huge improvement over the original wiring but clearly it was time for labels and a wiring diagram.

Chris Gammell asked me to give a presentation at his Hardware Developers Didactic Galactic meetup in San Francisco. I enjoy talking about things I work on so I didn’t hesitate to say yes. I’m pretty sure he was expecting me to talk about Google’s Zaius server, an open-hardware POWER9 server design, that I brought to a previous meetup. Giving presentations about my day job takes some review and approvals, even for open designs. Instead, I offered to talk about engine control, a subject I’m spending many nights on recently.

After working out the serial port pinout on my MoTeC M48 (see MoTeC PCI Cable for $20), I was left with one unidentified pin. As the same DB9 is used with both a PCI cable and a SUU, I suspect this extra pin is how the ECU distinguishes between the two. My M48 is already running the latest firmware so figuring out how to emulate an SUU isn’t a critical but not knowing how it works bothers me.

After getting the MoTeC M48 EMP software installed in Dosbox as described previously, I naively assumed the M48 just connected with normal RS232 serial. I mean, there’s a DB9 hanging under the dash and the EMP software is looking for a serial port. Of course it couldn’t be that simple.

A few month ago, a coworker decided to buy a built drag racing car and was looking for someone to help crew. I emphatically offered my services and we started working out what exactly he had bought.