Different Differentials & The Pitfalls of the Easy Swap

I dig cars, and I do car stuff. I started fairly late in life, though, and I’m only just starting to get into the whole modification thing. Now, as far as automobiles go, you can pretty much do anything you set your mind to – engine swaps, drivetrain conversions, you name it – it’s been done. But such jobs require a high level of fabrication skill, automotive knowledge, and often a fully stocked machine shop to match. Those of us new to the scene tend to start a little bit smaller.

So where does one begin? Well, there’s a huge realm of mods that can be done that are generally referred to as “bolt-ons”. This centers around the idea that the install process of the modification is as simple as following a basic set of instructions to unbolt the old hardware and bolt in the upgraded parts. Those that have tread this ground before me will be chuckling at this point – so rarely is a bolt-on ever just a bolt-on. As follows, the journey of my Mazda’s differential upgrade will bear this out.

The car in question, currently known as the “Junkbox MX-5” until it starts running well enough to earn a real name. It somehow looks passable here, but in person I promise you, it looks awful.

It all started when I bought the car, back in December 2016. I’d just started writing for Hackaday and my humble Daihatsu had, unbeknownst to me, just breathed its last. I’d recently come to the realisation that I wasn’t getting any younger, and despite being obsessed with cars, I’d never actually owned a sports car or driven one in anger. It was time to change. Continue reading “Different Differentials & The Pitfalls of the Easy Swap”

Homebrew ECU Increases Mazda Zoom

A big problem with most modern cars is the sheer number of parts and systems that are not user serviceable. This is a big departure from cars of just decades ago that were designed to be easily worked on by the owner. To that end, [Anthony] aka [fuzzymonkey] has tackled what is normally the hardest thing to work on in modern cars: the Engine Control Unit. (Older posts on this project can be found at [Anthony]’s old project log.)

Every sensor in any modern car is monitored by a computer called the Engine Control Unit (ECU), and the computer is responsible for taking this data and making decisions on how the car should be running. In theory a custom ECU would be able to change any behavior of the car, but in practice this is extremely difficult due to the sheer number of operations required by the computer and the very specific tolerances of a modern engine.

The custom ECU that Anthony has created for his Mazda MX-5 (a Miata for those in North America) is based on the PIC18F46K80 microcontroller, and there are actually two units involved. The first handles time-sensitive operations like monitoring the engine cam position and engine timing, and the other generates a clock signal for the main unit and also monitors things like cooling temperature and controlling idle speed. The two units communicate over SPI.

[Anthony]’s custom ECU is exceptional in that he’s gotten his car running pretty well. There are some kinks, but hopefully he’ll have a product that’s better than the factory ECU by allowing him to change anything from throttle response and engine timing to the air-fuel ratio. There have been a few other attempts to tame the ECU beast in the past, but so far there isn’t much out there.

Continue reading “Homebrew ECU Increases Mazda Zoom”