ECU Reflash Remap tuning a Honda City 1.3L

Remapping a car Is actually quite a boring process to watch. There are no sexy parts that get installed, a lot of keyboard and numbers tapping and uploading screens, kinda like normal office work. Except that the office is located behind the steering wheel of the car.

ECU remap/reflash, where the contents of the ECU is read, modified with different values and then uploaded back into the ECU, exactly like how you share files and pics between phone and laptop.

So what exactly do we change and modify? Well, all engines around the world need 3 things, air fuel and spark. It doesn’t matter if it’s Ferrari, Mercedes or Cherry, it has to have these 3 things.

The air part is pretty much fixed, and in the case if this 1.3L City, it’s 1.3L of air going into the engine.

The things that we can adjust are the amount of fuel the engine gets and when the spark plug fires. And this is what the remap software screen looks like

On the left column are all the parameters that can be adjusted. Note that it’s also not something as simple as ADD Fuel here and ADD Spark here. The right side is the table where in the values are for each parameter, in this case it’s the “Spark Advance when the High Cam VTEC is engaged” table, or map (hence the term remap) and the numbers inside the table are degrees of timing.

Here’s a closer look at some of the things we can adjust

Now if that’s a lot to take in and you’re confused, don’t worry, that’s natural. You’re really not supposed to understand any of this unless you specifically study it and have hands on experience, kinda like I don’t expect you to know how to code using C++ or even use Photoshop at first glance.

“But you’re just changing a bunch of numbers!!!”

Well sorry to burst your bubble but that what tuning really is, changing the values to see which combination yields the best results.

And that’s what you’re actually paying for, not for us to enter a bunch of number in some tables but WHICH TABLES and WHAT NUMBERS that will be entered. In short you’re paying for our brains power and the know how.

When we tune a car, we also take into account what has been done, and in this case, the little 1.3L has a K&N intake and a too big diameter exhaust pipe that causes a big drop in power and torque at 3000rpm, just where you need it most for overtaking, as seen in the Dyno chart below.

Red line: Baseline power

Blue line: SpeedLab ECU tuning

Why this power and torque drop happens is because the big exhaust causes the engine to lean out, meaning too much air, not enough fuel.

So we added fuel to get the mixture back correctly and added ignition timing or Spark Advance. Other things we adjust are throttle pedal sensitivity, throttle opening, rev limit at park etc etc

And as you can see from the above graph, gains are 15-20hp across the rpm range and 10-20 ft-lbs and a very flat torque curve which is very ideal.

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