Honda FK8 Tuning Guide

 

The FK8 Civic Type R marked a fairly big deviation from many of the previous engine platforms made by Honda. Utilising a Bosch ECU, the torque based tuning is going to be much more similar to the EcoBoost engines found in Ford vehicles, as well as the VW/Audi/Porsche offerings.

Like many other torque based systems found in porsche, vw, and ford, the FK8 doesn’t target a specific boost pressure. Rather it targets an amount of torque based on the amount of accelerator pedal input it’s seeing, and makes the boost required to hit that torque.


Tips for Reflashing

After every re-flash, there will be a time delay before the intake and exhaust cam phasers and fuel trims reactivate.  Allowing the car to idle after a reflash (while already warm) for 5-10 seconds without touching the throttle appears to be sufficient to bring the cams back online, but fuel trims will take around two minutes of driving to reactivate.  Simply idling the car will result in significant delays for fuel trim reactivation, so it is recommended to drive the vehicle easily on the dyno or street until movement is seen on STFT.

There are two ways to fully deactivate traction control for testing on the dyno.  The easiest way is to toggle the vehicle into “R” mode and then press and hold the traction control button (located left of the steering wheel) for approximately 10 seconds until a message is shown on the dash stating “Stability Control Fully Disabled”.  Traction control cannot be fully defeated with a press-and-hold of the TC button while in Sport or Comfort drive modes.

The only way to fully disable TC in Sport mode is to use the following “Konami code”.  Note that this will reactivate TC after one or two pulls.

  1. Key on, engine off.  Engage emergency brake.

  2. Disengage emergency brake.

  3. Press and hold brake pedal (continue holding until Step 6).

  4. Turn traction control on and off (~3 second hold for each).

  5. Engage emergency brake.

  6. Release brake pedal.

  7. Turn traction control on and off (~3 second hold for each).

  8. Press and hold brake pedal (continue holding until end of Step 9).

  9. Turn traction control on and off (~3 second hold for each).

The dash should illuminate with a variety of ABS/Stability Control/Traction Control messages.

 


Fueling

Utilising full-time closed loop fuel control for it’s direct injection fuel delivery, these vehicles make fairly constant adjustments to the delivery to make sure it’s hitting the intended target. While the fuel system is generally adequate for bolt-ons with the stock turbo and E10, you’ll need to limit airflow in some ranges in order for the fuel system to keep up with more significant modifications, or higher ethanol content as the fuel mass and pressure delivery for the high pressure fuel pump (HPFP) can become a limitation as demand increases.

 

Much like other modern direct injection vehicles, the FK8 uses a mechanical high pressure fuel pump driven off of the camshaft. Pressure is regulated by a spill-valve which is controlled by the ECU with a typical output of ~2900psi at full load. The target rail pressure tables are broken up depending on what injection state the vehicle is in, and whether the vehicle is idling.

As you change the target air-fuel-ratio (AFR/Lambda) you can quickly run into limitations of the stock HPFP in some conditions. As such keeping an eye on the pressure target compared to what is actually being supplied is fairly critical to maintain a safety margin for the engine and catalyst.

Injection Window

A Start of Injection (SOI) table is available however there isn’t a significant amount of room in order to expand this much beyond stock values, we generally recommend leaving this table quite close to stock for most vehicles.

 

Power Enrichment and Component Protection

These vehicles offer both an enrichment target table which will enrich the fuel mixture based on throtle position or load, as well as a component protection system which will alter the air fuel ratio when various temperature or time limits are achieved. Both will alter the fuel target when active.

Once the protection threshold has been exceeded, the ECU references two tables as an enrichment target. Target Lambda (Catalyst Protection) and Target Lambda (VTEC) (Catalyst Protection). These tables use air charge and RPM as axes and will adjust the feed forward target AFR.

 

Oftentimes during vehicle operation, target lambda will be more rich than seen in these tables. The mixture will skew more rich as the system attempts to keep the catalyst within the desired temperature range. That means the mixture will be adjusted when it’s too hot as well as when it’s too cool. Table Minimum Lambda (Catalyst Protection) sets a lower boundary on how rich the AFR target can be commanded by this system.

 


Ignition

Commanded Timing

Ignition timing is determined through eight base tables which will describe the timing curve during different valve lift and came phasing states. Tables labeled with (VTEC) are used when VTEC is active. Blending between these tables does occur when the intake and exhaust camshafts are moved through different positions based on throttle request, engine temperature and spool state.

The system uses Air Charge as an upper axis limit. This limit can be exceeded on the stock turbo so it’s likely that you’ll need to increase these values depending on your desired amount of load in the calibration. Significant timing advance can be added without seeing knock, however the final total advance is limited by fuel quality. As these vehicles don’t currently offer a vast array of timing compensation tables, it’s a good idea to tune carefully if you’re calibratingthe vehicle in cooler air temperatures.

 

Knock Control

Timing on these vehicles is corrected per-cylinder in response to knock events, the step size (how much timing is removed) is adjustable via Knock Retard Step which uses knock ratio and RPM to determine how much to remove.

Knock Ratio is an indication of both engine noise and knock intensity. As knock ratio increases, the severity of the knock which was detected increased, and in turn the calibrated timing correction should increase. Stock the step size is -3 however smaller corrections could be used.

 


Cam &Valve Timing (VTEC)

VTEC - variable cam lift and duration
VTC - Variable cam timing

The FK8’s timing arrangement is fairly different from previous engines. When looking at the popular K-series engines, their performance models had variable lift and duration on both the intake and camshafts. For the more “economy-minded” vehicles, VTEC was only offered on the intake camshaft. However the FK8 only uses variable lift and duration on the exhaust camshaft lobe, setting it quite apart from the naturally aspirated vehicles.

Commanded VTEC

This table is a fairly simple on-off switch for the vtec, where 0 will indicate a the lower lift/duration cam profile, and a 1 means the system is on, and the car is running the high lift/duration profile. A value of 100 is used in areas where the system is on the border of engagingvtec. When adjusting boost (and the accompanying changes to exhaust manifold pressure (EMAP)) it may be a valuable to modify the engagement point.

 

VTC

Unlike the simpler VTEC table, the VTC system uses multiple tables in order to control the positions of the intake and exhaust cam in reference to engine temperature, spool condition, and engagement of VTEC.

 


Torque/Airflow

The ECU found in the FK8 uses a torque-based control strategy in order to modulate airflow and boost requests. These systems typically use a dedicated torque model from which everything is compared or referenced, taking into account the ideal output of the engine under perfect conditions. There are additional compensations such as spark efficiency (a measure of distance between actual spark angle and a calibrated or modeled MBT), as well as for Air-Fuel ratio (Lambda) and VTEC and VTC timing (Cam phasing/Lift).

Requested Torque

Each gear and drive mode have their own requested torque tables based on the accelerator pedal and current engine RPM. Changing spots not under wide-open-throttle conditions can adjust throttle sensitivity, or decrease/increase torque available under certain conditions (i.e. reducing power up top to prevent slamming into a limiter, increasing power down low to offer a snappier pedal response). Keep in mind your torque request will need to be increased to hit higher torque/airmass output seen when increasing power. These tables are also gated by the Torque Limit table.

 

MAF

The FK8 uses a MAF sensor located in the intake system pre-turbo. Much like other MAF equipped vehicles, this will require adjustment when changing parts on the car that affect airflow. Luckily it does have quite a few monitors needed to tune such as MAF Sensor V, Short Term Fuel Trim (STFT) and Long Term Fuel Trims (LTFT).

The sensor has an upper limit of 4.96V which is attainable on the stock intake, MAF housing and turbo at higher RPM. Exceeding this limit will give you a DTC (P0103) and put the vehicle into limp mode. Decreasing airmass targets, or swapping to a larger MAF housing and recalibrating the MAF curve can solve this issue.

 

Boost Limits

The torque target for the vehicle is translated to an airmass target, and then a pressure target. There are several additional tables that are designed to protect the compressor, which in turn can limit the pressure target. These limits are frequently active at WOT and outside of increasing torque requests are the main table that will need to be (carefully) modified when increasing boost pressure.

Values in these tables are pressure ratio across the compressor (Compressor outlet pressure vs inlet pressure) prior to modeled pressure loss between the outlet of the compressor and the intake manifold.

Turbo Max Ratio (PA) is a limit to boost based on barometric pressure. The X-Axis (PA) is a ratio of measured barometric pressure vs standard pressure (1 BAR). As barometric pressure decreases, PA decreases and maximum allowed compressor ratio decreases as well in order to keep turbo shaft speed controlled at a safe level.

 

Turbo Max Ratio (PA) Comp. (IAT2) is a 2D curve that adjusts the calculated PA ratio based on intake air temperature. As temperature increases, the compensation will lower the PA limit.

 

Turbo Max Ratio (Temp) is used to limit boost based on intake air temperature. The X-Axis is a measured temperature from before the turbo charger. As air temperature increases, the maximum allowed compressor ratio decreases to keep turbo speed controlled.

 

Intercooler and air filter pressure drops are controlled by a few different tables which correlate the amount of air flow with pressure drop. We believe that the pressure drop is applied to PA in order to model compressor inlet pressure, and that the intercooler pressure drop table is a good chunk of the drop seen between outlet pressure and manifold pressure targets.

 

Air Charge Limit while not used in most of the factory calibrations, looks at engine speed and applies an air charge limit to the vehicle in response.

 

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