The OBD and the Myvi – the beginning

Note: Some might be aware there is a password protected page before this. This post was supposed to be out before it, so you don’t have to worry if you think you’re missing any part of the story.

As a person with strong interest and literacy in technology and weird curiosity, I loved to see how things worked. I would tear down casette tapes, stereos, and basically almost anything attached together with screws, and ogle at the little shiny bits and weird shaped objects hidden from view. Of course, the entire thing at most times wouldn’t work exactly the way it should after I reassembled it, but hey you now know how it works, right?

Fast forward to today. I still break open stuff – but as a responsible adult I leave them in at least the same, or better condition when I was done with it. Now when I finally bought my own car, and a car hasa computer and many screws inside – we all know what comes next.

I started this little project almost two years back. It started with a simple thought with the average fuel consumption meter on the meter cluster – how does it work? How do I know if it’s accurate? Why could it only show me the average? Then, there was a day which I was driving my cousin’s VW Golf MK6 and it could display fuel consumption at that very instant, which I thought which would be more practical to achieve a more fuel efficient drive with the Myvi.

Logic first, every car has an ECU – acronym for Electronic Control Unit which basically is a computer for the car’s engine. When you step on the gas pedal, you allow more air into it; which the engine in turn will calculate and instruct to provide sufficient fuel for the mixture to ignite. The explosion is turned to mechanical power, which turns gears and moves shafts, which makes the car go. Now with this in hand the car would definitely have some sort of sensors to monitor these events – but are the conditions monitored by these sensors available to the driver? Again, logic says yes as when you have an engine problem, there’s got to be a way for the mechanics to see what’s happening in the engine, and how the computer is reacting to the situation. Enter OBD2.

OBD2, which stands for for On-Board Diagnostics, with 2 being the revision is a term car enthusiasts would certainly come across. Simply put, it is a standard where a car’s ECU may report its condition via a receptacle common to all manufacturers, also known as an OBD2 port. Error codes are thrown and read from the same port, which simplifies diagnostics and repairs – but as hinted above they can be used to report sensor values, which the end-user may utilize to monitor the health or performance.


The OBD2 adapter to connect your car’s ECU to your laptop/car.

Fortunately, getting a physical connection to the ECU is easy. Unfortunately, getting your OBD2 cable or tool to communicate with your ECU is tough. Some ECUs work plug and play with the tool which they use settings common to many other vehicles, whereas some need a bit of tinkering to get both sides to handshake. There’s not much documentation on this process either, which I had to rely on a lot of experimentation and trial and error to get it working. I can’t tell how many times which I tested different setups to get the tool and ECU to connect – and when I finally succeeded, you bet I was excited to see it finally responding.

Once you have it connected, you can finally diagnose your own CELs and clear them if needed – certainly a very useful feature for those home mechanics or DIY enthusiasts. Also available to you would be the real-time sensor readings, which you can monitor certain vital engine parameters as you drive. Want to see if your CAI works? Install it and monitor your intake air temperatures. Is the car experiencing poor fuel consumption? Check the fuel trims and you can find how much the ECU is compensating. Need to know at what speed your car is the most efficient? Plot out your RPM, vehicle speed and fuel consumption against a graph. There’s certainly plenty more that you can do.

Next post, I will be taking a look at the available sensors that can be read, and also see what else is possible with the OBD2 tool.

PS. For those who are wanting to get one your 2011 Myvi/Alza, I’m currently selling an OBD2 adapter which is guaranteed to work on your car. It’s definitely worth the price, and you’re directly supporting the work of yours truly 😉





Leave a Reply

Your email address will not be published. Required fields are marked *