Hondata Tuning Guide
This guide covers the specifics of tuning a 2017+ Honda Civic Type R from start to finish using a Hondata FlashPro. It is meant for those that are already familiar with EFI tuning and the Hondata interface. There are many videos and courses online about both of those subjects, so many general topics won't be covered in depth here in order to focus on techniques specifically for the FK8. If you do not understand the fundamentals of EFI tuning, you should not attempt to follow this guide blindly. An FK8 ECU is great for someone to learn tuning on, but you must understand electronic fuel injection first.
This guide is meant to be read from start to finish. General information regarding tuning a Type R can be found on the Tuning article.
Disclaimer
You are fully responsible when using the information in this guide. This is meant to be purely informational on a platform where there is very little info, and some things may not be correct or even safe. New techniques and problems with old techniques are constantly being found.
Core Concepts
First thing's first: the 10th generation Civic Type R does not have a Honda ECU. It is a Bosch MED v17.9.3 and tuning is approached in a wildly different way than any USDM Honda before it. The engine is different from most K series as well, having exhaust-only VTEC, a relatively low flowing head, an integrated exhaust manifold, and of course a factory turbo.
There are two core concepts you need to be intimately familiar with when tuning a Bosch ECU.
Air charge
The Bosch ECU uses a significantly more accurate index for targeting fueling, ignition, and cam angles. It calculates what is actually inside the cylinder rather than the overall flow through the intake and engine. Air charge is a ratio expressed as a percentage of the physical mass/amount of air in the cylinders at bottom dead center compared to how much the cylinders would hold at the currently measured atmospheric pressure. Anything above 100% and the engine is under boost, anything below 100% is vacuum.
The actual mass of air throughout any turbocharged application's intake and cylinders varies wildly, particularly during sudden throttle changes. Things like VTEC engagement can significantly change the amount of air in the cylinder for each stroke despite the overall flow and calculated engine load not immediately changing.
By having a measurement of the mass of air in the cylinders instead of just what is passing by the MAF sensor or how much pressure the manifold is under, the Civic Type R is able to target a theoretical amount of torque reliably under all environmental and operating conditions with significantly less room for error, regardless of what modifications are installed.
Air charge is very similar to both SAE absolute and relative engine load and uses the same sensors, but the calculations are time-domain rather than instantaneous and are also significantly more complex. The actual formula is not known or standardized like SAE engine load, but we can guess. The ECU will first track how much air has flowed past the MAF sensor into the charge pipes, figuring out how much pressure that airflow is maintaining before the throttle plate using the boost pressure sensor. It will then watch the manifold pressure after the throttle plate to determine how much of the air is leaving the intake manifold and thus (hopefully) going into the cylinders.
Because the ECU is sampling the MAP sensor in high resolution in order to properly measure the pressure drops as the intake valves open, it will usually fluctuate wildly under load by 1-3 psi.
