Tuning Notes

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Also see Turbocharger_Notes


For the 2015 (FK2) and 2017 (FK8) Civic Type R Honda has used an ECU made by Bosch.  This ECU is different from Honda ECUs used in previous vehicles.


The ECU needs to be opened and reprogrammed ('jailbroken') to allow OBDII programming with a FlashPro.
Tables, sensors and tuning are different.


Fundamental differences

Honda ECUs tend to be table driven - for example, in order to work out the throttle plate angle the Honda ECU typically looks up a table based on engine speed and throttle pedal angle to find the target throttle plate angle.

Bosch ECUs use a mathematical model of the engine to find target values for most outputs.  Typically the Bosch ECU will start with a desired wheel torque and calculate the required manifold pressure to achieve that force.  For the same example as the Honda ECU the Bosch ECU will work out the engine torque necessary, then the cylinder filling necessary modified by the current ignition timing, lambda, accessory load etc and from that calculate the necessary manifold pressure.  From the manifold pressure the Bosch will then calculate the throttle angle and also the boost pressure if necessary to achieve the cylinder filling.




Air flow

Make sure that there is enough air flow over the intercooler, otherwise ECT will be high, boost will be high, but power lower than expected.  As a guide the IAT temperature at the end of a dyno run should be no more than 45F higher than ambient temperature.



To fully disable VSA for the dyno either use R Mode and hold down the VSA button for 10 seconds, or disable as below:

1.Switch on ignition but do not start engine.  Release the parking brake.  Press the brake pedal.
2.Turn traction control on and off
3.Switch on the parking brake on and release the brake pedal.
4.Turn traction control on and off
5.Press and hold the brake pedal
6.Turn traction control on and off

Note that this must be done each time the ignition is switched on.




Cam angles / VTC

Bosch cam angles are relative to a central zero position.  A typical intake camshaft range is -25 degrees to +30 degrees, and the exhaust camshaft range is -25 degrees to +20 degrees.  The cam overlap and phase is used to help turbo spool up.


It is important to note that the Bosch VTC table and datalog values are reversed from previous ECUs.  A negative value indicates advance, a positive value indicates retard, for both intake and exhaust camshafts.



VTEC is exhaust only and controls the exhaust back pressure, which also affects the turbo.  VTEC is switched based on rpm and air charge. VTEC is off at idle, on at cruise, off when the turbo is spooling and on at high load.



IAT is part of the MAP sensor on the manifold.  IAT2 is part of the AFM on the intake.





After reflashing the lambda will take around 2 km and 2.5 minutes to read.  On a dyno it is best to run the vehicle until the lambda starts to read, otherwise the engine may run richer or leaner than intended.



After replacing the ECU or reflashing it is best to start the TPMS recalibration otherwise a low tire pressure error may occur after a few miles.




Fuel trim

US vehicles have been calibrated for ethanol free gasoline so it is best to change the overall fuel trim to 4% (a modification is available to do this).


Short / Long term fuel trims

The short and long term fuel trims do not behave the same way as Honda ECUs.  Both act as short term trims.  Do not be alarmed when the long term trim changes quickly.


Bosch Table/Parameters


Air Charge

The Bosch ECU will use 'air charge' as an index in preference to manifold pressure.  Air charge is the amount of air in the cylinder where 100% = 1 atmosphere pressure.


Target lambda

The target lambda tables are target lambda, not WOT compensation like the Honda ECU.


Throttle Tables

There are target torque tables for each gear and each mode (comfort, sport and R).  All other things being equal, simply increasing the torque values in these tables will generate more power.


Torque Limit

This table limits the overall engine torque.  It is best not to modify this table because the feedback loop is long and can led to oscillations.


Rev Limits

Rev limits used multiple tables with indexes such as gear, speed and temperature.



There are ignition tables for each cam at fully advanced and fully retard positions in four combinations, for VTEC off and VTEC on.  ie 1. intake cam retarded, exhaust cam retarded.  2. intake cam advanced, exhaust cam retarded.  3. intake cam retarded, exhaust cam advanced, intake  cam retarded, exhaust cam retarded.  The actual ignition timing is interpolated between the four tables using the actual cam angles.


The Bosch ECU stores ignition values in units of 0.75 degrees.  You cannot make a change to the ignition table value smaller than 0.75 degree.



There are cam angle (VTC) tables for the intake and exhaust cams for normal operation, cold engine operation and turbo 'spool' operation.  Again, for VTEC off and VTEC on.



VTEC is controlled by rpm and air charge.  A table value is 100 indicates a transition value to provide hysteresis control.


Pressure Ratio

There tables (PA, IAT and IAT2) control the maximum pressure ratio of the compressor. If the engine is making less boost than expected than these tables may be the limit.


Injector Phase (SOI)

This table controls the start of injection point in crank degrees before TDC.  If the injection event becomes long enough then the fuel will not have time to vaporize before the spark.  In this case the SOI should be increased.  The SOI should be be increased unnecessarily as it will retard spool up.



Engine Modifications


Intakes. Often require the AFM table to be tuned if the intake alters the air flow. We do not have enough data to determine how intakes affect engine power.


Intercoolers.  Appear to work well.  Do not require special tuning.


Exhausts. Make no difference to tuning and little different to power under 400hp.


Downpipe.  Require slightly different cam angles and give a slightly earlier spool, but only very slight gains in overall power.


Octane.  Is the single bigger modification to increase engine power.


Ethanol.  The ability to run ethanol is limited by the fuel pump delivery.


Mechanical. Keep mechanical components quiet is important to allow the knock sensor to work correctly.  Sometimes a modification can reduce power by creating more engine noise.


Rev limiter. We do not recommend raising the rev limiter from the factory setting of 7000 rpm.  The high pressure fuel pump will float and be damaged at 3600rpm (7200 rpm engine speed).


Bosch ECU Tuning


Intake.  If the intake has been changed then tune the AFM Flow table until the fuel trims are close to zero.


Lambda.  The ECU will target stoichiometric 100% of the time.  This cannot be changed.  Using exhaust temperature models the ECU will enrichen the target lambda to protect the turbocharger and catalyst, so normally the mixture will run richer than stoichiometric over about 4500 rpm.  Use the minimum lambda table to stop the lambda going too rich.  Note that leaning out this table may be detrimental to the catalyst.


Fuel Pump.  The stock fuel pump is very close to the limit even at modest power levels.  This is a volumetric fuel pump so the capacity is based on torque rather than power.  Datalog the fuel pump duty cycle and keep the duty below 90-95%.  Use the air charge limit table to control the fuel pump demand.  If the fuel pump duty reaches 100% then the fuel pressure will drop.  If the fuel pressure drops then the ECU will compensate for a short period of time, but will eventually go into a protection mode with reduced power and rich fuel mixtures.


Torque/Boost.  Can be controlled using either the throttle tables or air charge limit tables.  On anything other than high octane fuel often reducing torque demand can increase actual torque by running the compressor in an area of higher efficiency and using less boost so that ignition timing is higher.

Stock calibration values limit the boost based on PA (to limit turbo speed), IAT (to limit compressor discharge temperature) and EGT (to limit turbine and catalyst temperature).  These limits may be disabled using modifications.


AFM limit.  Even a stock engine will reach the voltage limit of the air flow meter (5V).  At modest power levels (under 400 hp) this will result in a slightly leaner top end but will still be acceptable.


Ignition timing.  Generally change all ignition tables by the same absolute amount.  It is best to avoid any knock events as they will reduce engine power for a short period each time.


Knock.  Changing the knock retard step table to reduce the knock retard upon a knock event helps to stop large drops in engine power from a single knock event.  If there is knock retard after 5000 rpm without any sign of knock, consider changing the knock sensitivity tables.




ECU removal / replacement. When the ECU is removed and replaced often a P056x error code is generated (system voltage high / malfunction).  In this case, clear the DTCs using FlashProManager and cycle the ignition.


TPMS. If the ECU has be replaced then a low pressure warning may be shown.  In this case on the radio under Settings, Vehicle select recalibrate TPMS.


ECU DTCs If any ECU error codes occur then the cluster will cycle through errors for every sub system (emissions, rev match, TPMS etc).  You must read and clear the error codes using FlashProManager.


VSA DTCs If the vehicle is run on a dyno without disabling VSA then the cluster will cycle through errors for every sub system.  The ignition will require three presses to switch off and some speed dependent features of the radio will not work. There is no ECU DTC so these codes can only be cleared with the Honda tool or by driving 20 km.


Fuel Pressure

There are two fuel pressure tables - normal and split injection.  Split injection is where the ECU will injector some fuel on the intake stroke and then again on the compression stroke.  This only occurs at low-medium load and may not be used at all for the FK8.  Split injection may be disabled under closed loop.

The fuel pump output decreases with pressure, so lowering fuel pressure will give slightly more volume, however in dyno testing we have found that reducing fuel pressure will lose power.  The fuel pressure is limited by the ECU to 200 MPa.


Blow of valves

'Blow off valves' which vent to atmosphere result in the engine receiving a different amount of air as that measured by the air flow meter.  As a result the engine will run very rich when the BOV operates. Do not use blow off valves. Internally recirculating valves like the stock recirculation valve are acceptable to use.