Tuning

Bosch ECU and torque targeting

The Civic Type R 2017+ features a Bosch-made MED17.9.3 ECU rather than one made in-house by Honda. Notably, even the Accord that shares the K20C1 engine uses a Honda ECU and not the Bosch ECU. It is largely the Bosch ECU that makes the Civic Type R the most powerful Honda ever made.

The methodology by which the Bosch ECU makes power and is tuned is significantly different from Honda-made ECUs. The ECU outputs all begin with the pedal position corresponding to a requested amount of torque for each gear and drive mode. Using a built-in mathematical model of the engine, the ECU will determine the necessary combination of air charge and ignition advance to output the requested torque to the best of the engine's ability, up to the limits defined in various safety tables.

The ECU will determine the appropriate throttle plate and wastegate position to reach the calculated amount of manifold pressure necessary to fill the cylinders to the target air charge. There are no tables available for these calculations, and as such a tuner cannot target a set amount of boost. Comparing tunes or results based on the targeted PSI as with other platforms is thus meaningless.

Balancing between air charge and ignition advance

The FK8 comes equipped with the Mitsubishi TD-04 turbocharger. Due to it's small size and fin configuration, it excels at rapidly spooling but quickly loses efficiency in the upper RPMs. This is where variable cam timing and VTEC come into play, controlling exhaust backpressure. An FK8 will typically increase the backpressure in lower RPMs in order to decrease turbo lag, and subsequently decrease exhaust backpressure in the upper RPMs to allow for more ignition advance once the turbo can't keep up. This is what allows the Type R to have such a large power band, pulling hard at almost any RPM and keeping the power till redline.

It is important to know that the ECU appears to favor using air charge (and thus boost) over ignition advance to make the requested torque whenever possible. With torque request kept the same, adding ignition advance sometimes results in little to no actual change due to the ECU determining it has already reached the torque target. Requesting additional torque will mostly only add more air charge unless the air charge is limited by other tables.