Six panels of a custom dashboard

Hacking your car (for fun and profit)

My car returns 32mpg – according to the official stats. It’s a two litre car that, judging by is performance is already detuned for economy.

And, frankly, that’s horrific.

So I decided to do something about it, and now my car is getting a real world average of 43mpg, so near enough 25% better fuel economy through some modest changes to my driving style and a couple of extremely cheap additions to the car. That, as you might say, isn’t bad. You’ll need a car manufactured after 2006 to get the best out of my guides here, but some advice is of course universal.

I say cheap, you’ll need a smart phone – and if you’re following this guide faithfully it won’t be anything from those “apple” types, fortunately that means I can still put this within a modest budget. The exact device isn’t important, but Bluetooth is, especially if you want to pop panels back after you’ve finished setting up. I would also suggest some kind of mount, preferably close to your natural driving eyeline – in the early stages you’ll be glancing at your phone instead of your dash.

Next, pop into eBay and grab yourself an ELM327 Bluetooth adapter, this should at you back about a fiver. While you wait for this to arrive, you should locate your in-vehicle ODB port – this is a big D-connector hidden somewhere in the car with you, it shouldn’t be too hard to find as there’s legislation regarding how far away from the steering wheel it’s allowed to be. While you’re frantically googling for that, take a moment to visit the play store and grab “Torque Pro” by Ian Hawkins available here – it’s cheap, and it’ll do you proud for your first steps in to increased efficiency.

Plug your ELM327 adapter into your car, fire up Torque and go through setting up a new vehicle profile. Launch the realtime dash and you’ll see a handy little interface for creating your own little dashboard.

Six panels of a custom dashboard
My initial setup

Awesome, now to help me get my mileages up I added an instantaneous MPG gauge, an MPG histogram, current vehicle speed, current trip cost and a couple of others for interest. If you set up the same deal, then immediately you can start getting feedback on your driving profile and how minor changes to your driving style get that magical MPG number up. First thing I noticed was how vague the response to pedal position was in terms of acceleration – as a fly by wire throttle the position actually represent driver demanded load, and as such it seems to allow quite large differences in throttle opening from small changes to the pedal position.

This meant that while I was cruising I was losing about 4-7MPG in typical driving conditions, just because I could ease my foot off the pedal a degree or two and not lose speed.

Once I’d realised this, I added some more gauges; I’d become interested in how the ECU was making fueling decisions based on the available data, so I popped the fuel trims onto a couple of gauges and watched. Immediately I realised something was not right, the trim was batting back and forth by around 50%. What condition could cause this? A few minutes with a spanner proved that my sparkplugs where all well past their service gapping, and one had a cracked liner. A quick dash to the shops, tiny bit of checking with a feeler gauge and I’d snapped up another 3MPG, as well as getting rid of the slight (in retrospect obvious) hunting at idle. Making sure the tyres where fully inflated added a heart 1MPG to the matter.

A dashboard readout
555 miles to empty..

Now I’d gotten really interested in the architecture of the vehicle’s available communication systems, and I realised that I could make some more changes to the car’s behaviour through more involved tweaking. Having found out from some late night google-fu how to reset the learn-ins…

Ah, don’t know about learn-ins? Your vehicle is unique, because it’s made to a budget, not because it’s special. As a result there are lots of little bit of tolerance here and there that make a difference to how the vehicle behaves when compared to an absolute implementation of the engine’s blueprint. Tiny changes in the manufacture of critical components like injectors can result in very real implications for the running life of the engine. So, the engine management is given the capacity to learn how best to use itself to bring it back to it’s best running potential (and to a small degree, to learn how you drive it), by dialing in different fuelling decisions for different conditions.

With the learn-in’s reset, I found the car horrible, jerky and sluggish for the first ten miles… and then gradually it opened up into a soft and friendly ride; even the throttle pedal appeared to have a bit more leeway for that cruising effect.

That really whetted my appetite. At the moment, I’m writing a piece of software more details here to help me explore the rest of my car’s available programmable features – I’ll post more when I’ve got this into a more usable condition and can unleash it upon the world. I’m aiming to get to 50MPG; and when I do I fully intend to find out how I can get my car’s tax bracket reset!

My advice is offered as is and without acceptance of any liability for any loss or damage incurred as a result of such advice being followed even if I am aware of the possibility of such damage. You are responsible for all your actions.

3 thoughts on “Hacking your car (for fun and profit)”

  1. A buddy of mine (who works from the other end of these things – but without spoilers!), has pointed out that resetting the adaptive learn-ins is not always the best thing to do, he cites cases where the throttle assembly is caked in gunk, and moves out of it’s adapted ranges.

    It’s a good point, and I’ll say what I always say; you do this sort of thing at your own risk! I had a reason, and weighed up the pros and cons – always do the same.

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