Our cars keep getting smarter, especially their diagnostics

The thing is, I've always found computers and harnesses much easier to work with than carbies and points. I guess it's just a question of being willing to learn something new.

The first car I owned was a Mitsubishi Sigma, and so I did start out playing with carby cars. With a bit of fiddling with the secondaries (if you don't know what they are, that probably just means you're young), and a new distributor to replace a dud one, according to the stock tacho I had that Astron 2000 spinning up to 7000rpm (I wasn't exactly mechanically sympathetic in my teens).

All I needed was a workshop manual to tell me how to rebuild a carby. However, the modifications were a lot of guesswork with trial-and-error on my part, because my first efforts only introduced a noteworthy flat spot to the middle of the RPM range.

My next vehicle was a base model VL Commodore. And I do mean base model, an SL manual with not a single factory option. It didn't even have power steering (one of my favourite things about it, actually).

I wrung its aspirated RB30E up to 7000rpm as well, but tuning wasn't a DIY option for me at that time. It didn't really need it though, and what it did offer was self-diagnostics.

On the side of the ECU, tucked away behind the left kick panel, were two coloured LEDs that, when put in diagnostic mode, would flash in a specific sequence to say what piece of electronic hardware on the engine was in need of checking or replacement. All you needed was a workshop manual to find out what each sequence represented.

Later I started playing with '90s-era Ford V8s (and still do), and I found having more than one at a time to be beneficial (specifically, the tow car and the race car being fundamentally the same as each other). Diagnostic mode was less convenient to initiate, and so I used (and still use) the same basic method that a lot of mechanics used, that being swapping parts between the two cars until the opposite one plays up. I've identified several dud parts over the years without having to replace all of them each time.

I also learned how to DIY tune them with a reprogrammable chip, allowing me to give them bigger injectors, remap the ignition timing, and then run them both on either E85 (85 percent ethanol) or ordinary petrol.

I've played a bit with WRX tuning as well, but I'll save that for another story later.

My current daily (which seems like the wrong phrase to use this year) is an Alfa 147 diesel. When I bought it a few years ago, a mechanic mate of mine was absolutely sure it would fall to bits almost immediately.

Happily, despite being about the same age at the time of purchase (10-ish) as the Commodore and Falcons that did daily duties before it, it's had far fewer issues. In fact, nothing has gone wrong that I wasn't able to diagnose with my phone. Nope, not by calling for help, but by using an app that asks the engine's management computer to report any fault codes, and then it tells me what they mean. It's like the ol' VL, only better.

There's a cheap scanner plugged into the diagnostic port (that most cars have), and it communicates with my smartphone via Bluetooth. The app, in this case Torque which also has lots of other neat features that can turn your phone into a multi-gauge display, reads the fault codes, and once I've rectified the issue, I can also use it to clear that code.

The first issue was with number 3 injector. Its connection plug had some minor corrosion typical of this engine family, and some contact cleaner fixed it. It later identified other things that just needed cleaning like the EGR valve. The only part I've had to replace on the Alfa so far is a burst intake hose. Apart from the lost power and over-rich exhaust, various fault codes including the boost sensor were big clues to the real problem. And each of these was way less fiddly to clean or fix myself than the Sigma's old carby.

Sam Hollier is an ACM journalist and a motoring fanatic who builds cars in his shed in his spare time.