Forum » Practical Reflash Tuning » Trying To Understand Hondata S300

Trying To Understand Hondata S300

Practical Reflash Tuning

Discussion and questions related to the course Reflashing

Page 1

So I do NOT have the Hondata S300 yet. However, I have the software on my computer and am attempting to get familiar with the tables and everything. I will be getting this ecu soon to start learning how to tune on my own vehicle.

So for fun I pull up the d16y7, 550cc injectors, turbocharged map. When I look at everything it's so vastly different than what I was expecting, only having "tuning" experience on the PC Link in the live remote engine dyno tuning. So it raised a few questions.

What parameters are they using for fuel tables? As in I'm used to seeing the low numbers such as 45.3, 51.5 etc, they using numbers from 64 all the way to 2348. When using lambda does it not really matter what the numbers are in the table and so say if you need to take 10% of fuel out because it's 10% richer than your target would I just take the 10% off whatever number it happens to be in the cell I need to take it off from? Or does it depend on what the number in the table is to determine how the fuel will be added or taken out?

How can I identify which numbers they are using? Say percentage of injector time IE 50% 100% of a set value etc, the pulse width, how can I easily identify and know what numbers are being used as is what I mean basically?

Last two questions are, they have a low speed and high speed fuel table, same thing with ignition table, would the low and high speeds be used for engines with vtec, non vtec or are they for turboed applications? Last but not least, I could switch over to the target AFR table, then I converted it to lambda. Now the target fuel table itself I can not change like I can in the PCLink. I found that I can only change it through the settings menu which is a very broad from this load to this load it should be 1.0. then from this load to this load is should be 0.90. Then full acceleration it should be 0.85 and those are the only three options they give so is this the only way to adjust the targets is through these three options and the ecu interpolates it from there for the target table?

Thank you for any help. I'm new to tuning and everything in the performance world, so just am trying to gain as much knowledge before I can feel comfortable to get real life experience tuning something I never have before. It is much appreciated!


Hi Damen,

Welcome to the wonderful world of reverse engineered stock ECU's. On a standalone, the people who wrote the tuning software know how the fuel calculations work, even though they may not give you all the details. When reprogramming a stock (or in your case modified stock) ECU, the control system is reverse engineered. Somebody looked at the assembly code and did some testing to make educated guesses about where the tables are in the ECU and what they do.

That means you will see a lot of assumptions made and a lot of "well, we don't know what that table actually means, but we know what to change to make it do what we want." For your purposes the values in the fuel tables are directly related to injector pulsewidth. Higher number--> more fuel.

Do you have a wideband set up to your S300?

The low and high cam tables are for classic VTEC systems engines with just a low and a high lift mode for the cam(s). Later stuff like K series is more complicated. So when the VTEC switches into the high lift mode, it jumps into the new set of spark and fuel tables.

Ahh ok. I don’t have anything at the moment I’m just playing with the software and one of the maps that come already on it to see if I can get to understanding what I’m looking at which for the most part I do. It’s just the injector pulse width it’s using is vastly different from the pclink I used in the live remote tuning dyno lessons. Say on the pclink it would read 40s on up. Haven’t seen 100s yet so far for the fuel tables.

However when I open the s300 software it’s showing 64 up to 2,500 so I didn’t know it that changes anything or if I tune it the same. IE: say the cell I’m in the middle of is 1539. Lambda measured is 1.0 and target is 0.85. I would still just put 1.15 in the percentage calculator and that would add the 15% more fuel that I need correct?

Just making sure that the past 6 months of studying the lessons is sinking into my mind lol.

Thanks for the help.


Also for non-vtec applications, I would just ignore the Highspeed ignition and fuel tables as well correct?