one man. two cars.

zero cash.

The megasquirt mega saga - Part 1


Megasquirt 3 PCB assembled

When I first purchased my 1971 Datsun 240z, it was very much of its time... that time being 1992, following a restoration by its former owner. Many recent “enhancements” included fitting a sunroof ( oh dear ), Armorlite mag wheels ( fine on a hideous ChevV8 conversion, maybe ), and a closed-door respray in Toyota Red Pearl over the original factory 112 duco. The original L24 power plant had also been upgraded to an L28, and induction was via a Holley 350 carb bolted to a customised manifold using an adaptor plate. It was reliable and it went reasonably well, but the air cleaner fouled with the bonnet, and I really just dreamed of the day I could eventually replace it with the classic triple DCOE sidedraft configuration.

Weber sidedraft DCOE45 carburettors

But damn... have you seen how much they cost? I knew they were pricey, but when I saw sets of original 45DCOE Mikuni's fetching US$3,800, all I could see was my little dreamboat getting pulled by the tide of reality toward the distant horizon of despair. I decided the Holley still had to go, but I needed an interim plan, so I fitted a pair of HMB46W Flat-tops pulled from the wreck of wifey's 260z. After quite a lot of hole-plugging, tweaking, and dicking around with float levels, I got those damn things to run pretty well. But along the way, I hit upon the idea of EFI / EMS as a cheaper alternative, and I must admit I liked the idea of being able to dial up more power just by plugging in a latptop. I also figured general reliability and easy cold starts were compelling “pro” arguments.

In mid-2019 I started to investigate my options, and got my first feel for the market. At the entry/consumer level, Haltech's offerings looked solid, and I knew a couple of guys running them on Aussie 6's and small V8s. The Elite 750 and wiring harness came in at just over $2k, and I started seriously looking at it. I spent a bit of time talking to people, then started looking into what options I had in regard to tech support. And then I did some reading on the Haltech support forum. And then I read all the complaints from users about the lack of support. And then I discovered the guy who seemed to be the Aussie Haltech self-appointed gatekeeper. Alarm bells began to ring... and I abandoned both the idea and the brand soon after. If anyone from Haltech is reading this, hi! How's that manual going?


Speeduino EMS

I then started to look at options that were less turnkey/plug-and-play at the expense of doing more yourself. I figured that if I was going to have to work everything out myself I would need first and foremost, good, easily obtainable documentation. I was also looking for a bit more of a non-expert community, more street/performance-oriented than rally/drift/drag leaning. And in that small subgenre, I found two main players – Speeduino (based on the Arduino Mega ), and Megasquirt ( based on Motorola HCS12 microcontroller ). I did some reading up on Speeduino and initially, it seemed like an incredibly low barrier to entry. Open source as well, so there were all sorts of hacks and tweaks for specific applications. There was also a lot of information and a small but quite active online community. But despite the low cost, a few things did concern me. Random hard-to-solve bugs seemed to crop up on the forums regularly, and important documentation seemed outdated and often hard to locate. There seemed to be multiple versions of stuff in circulation. On top of that, it appeared to be very easy to completely destroy your engine inadvertently, with nobody to blame but yourself. As fascinating and as cheap as it seemed, I was not completely sold.

MS3 Megasquirt box

I wasn't naive to the Megasquirt and I'd often seen the EMS mentioned on forums like Hybridz. The platform was especially popular among the boosted community, and tuners seemed to love the flexibility and myriad of configuration options. After a bit of two-and-fro-ing, my mind was made up, and I began saving my pennies. I was weighing up the MS2 vs MS3, but eventually settled on the MS3 in kit form. It would cost several hundred dollars less, and having spent about 20 years putting circuit boards together I was not in the least bit phased about the build.

In April 2020 I created my account on, pulled out my credit card, and dropped $AUS511 on a Megasquirt 3 kit.

Two weeks later, the fun would begin...