Honda Civic Tuning Guide
- Brandyn Mowat
Honda Civic ProECU Tuning Guide
ROM Compatibility
There are Main Regions of ROM, these region ROMs are not generally compatible as there are many differences in the calibration and in some cases the Hardware (JDM cars do not have a MAF sensor):
- Euro - FN2 Cars
- US – FN2 Si cars
- JDM – FD2 cars
- Asia – FD2 cars as well
To see the latest version ECM ROM that should be chosen for your region, go to Feature & Licence Information under the Help menu, and the select the Supported Tuning ECUs tab.
Which ROM Version To Use
We recommend using the original ROM that came with the vehicle, if there are newer revisions like M120 and the M220 you may be able to swap these. If you connect to your vehicle and the ROM is unidentified please Dump the ROM using ROM dump in the programming window and submit the ROM with the relevant details through the ROM Dump Web form.
Accelerator
Accel to Throttle and Accel Trim Maps
These are simple, the Accel pedal to Throttle map is the throttle opening angle for a given engine speed and accelerator pedal % value. With RaceROM there are map switch mode specific maps that allow you to profile the trim of the accel to throttle map to any value you desire against vehicle speed.
Map List
Live Data Parameters
- Accel Position (%) Actual Accel pedal driver input (Default Parameter)
- Accel Position A (V) Actual Accel Pedal sensor voltages
- Accel Position B(V) Actual Accel Pedal sensor voltages
- Throttle Angle Actual (°) Actual Throttle angle (Default Parameter)
- Throttle Angle Target (°) Target Throttle angle (Default Parameter)
- Throttle Angle Target Idle (°) Target Throttle angle required for Idle
- Throttle Motor Duty (%) Duty cycle the throttle motor is being driven at to achieve throttle angle
- Throttle Position Sensor A (V) Throttle position sensor A voltage
- Throttle Position Sensor B (V) Throttle position sensor B voltage
Camshaft Timing
The Honda VTEC system combined with the Variable Timing Control (VTC) gives control over an additional “wilder” camshaft lobe and also allows the tuner to vary the intake camshaft angle. These maps can make a significant difference to power and drivability when set up well, there are a series of OEM maps that can be calibrated as well as some RaceROM VTEC activation maps.
VTC is the target cam advance angle and there are maps for Full Load and VTEC ON and OFF
Map List
Live Data Parameters
- VTC Intake Advance Actual (°) Intake cam advance angle measured
- VTC Intake Advance Target (°) Intake cam advance angle target from map outputs
- VTC Solenoid Duty (%) Solenoid duty used for VTC angle target
- VTEC Solenoid State (-) VTEC Solenoid state 1 = on, 2 = off 3 = switch on, 0 = switch off
Cam Angle
The Full load threshold to choose between the maps is believed to be manifold pressure but is yet to be defined.
VTEC Activation
VTEC is the switching point that enables the engines “higher lift” camshaft lobe to be engaged, the factory VTEC switches at a fixed RPM of around 5400rpm. RaceROM offers 4 x new VTEC switch maps, one for each mode and they offer VTEC switch against RPM and Manifold Pressure.
Fuelling
Like most ECU’s the Honda has a series of calculations that measure or estimate an airflow which is then tuned into an engine load amount (Honda uses mg/stroke) which is then used to calculate a matching volume of fuel depending on the target AFR. The first task of tuning fuel is to get the actual AFR to match the target AFR after this you can adjust the targets to find more power.
The Fuel Maps contain target AFR based on Engine Speed (RPM) and Manifold Absolute Pressure (Bar Absolute). These maps are used in both open loop and closed loop conditions. Fuel Map (Full Load) will be used when the ECU detect WOT and will use its Fuel Map - Full Load VTEC when it goes past the VTEC switch point. The X and Y axis scaling can be adjusted to suit higher RPMs or higher MAP if required.
The fuel maps are an AFR Target value and these work in closed loop on full load up to 12.6:1 AFR (the AFR Target Minimum). When not using WOT the Fuel Map & Fuel MAP VTEC are used with the same CL/OL switchpoint. There is also a safe mode fuel map pair that should not normally need adjustment.
The factory AF sensor is a wide-range sensor, this sensor has a good range but may not be particularly accurate, the Front AF sensor can be rescaled using a calibrated aftermarket wideband Lambda sensor for reference.
Map List
Live Data Parameters
- Fuel Injector Pulsewidth (ms) The measured fuel injector pulse width excluding lag time
- Fuel Temperature (°C) Temperature of the fuel (derived from fuel tank sensor)
- Fuel Trim Long Term (%) Learnt Closed loop fuel trim applied to reach target AFR
- Fuel Trim Short Term (%) Instantaneous Closed loop fuel trim applied to reach target AFR Injector Duty (%) Fuel injector opening time
Injector Scaling
The Injector scaling methodology for the Honda uses a base Injector pulse width for Lambda 1 map and makes compensations and adjustment to give the correct amount of fuel for the stock injectors. Using a RaceROM patch modifies this OEM methodology and adds a real injector sizing value that can be used to accurately scale the injectors. When using RaceROM to scale the injectors all you will need to change is the Injector size, open time compensations and minimum open time, which are generally available from quality injector suppliers.
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Some other features that have been added are
- fuel density maps, which allows alternative fuel densities to be accommodated for example if the car uses a specialised Race fuel mix.
- Accurate injector size maps (cc/min), shown above
- Injector Flow Multiplier and Offset, which allow for map switch mode dependant flow multipliers and offsets (to lag time) to be chosen. This could help account for the injector latency and flow rate changes when using the alternative fuels in discrete MS modes.
Injector size is 310cc on Euro and USA models and 370cc on JDM FD2 models.
Cranking and Starting
As with most ECU the Cranking fuelling is independent of the injector sizing calculation and the injector time is directly controlled until the cranking condition has ended. There is a base cranking pulsewidth map which may need to be adjusted when running larger injectors.
The ECT and IAT are also used to make corrections to this value and can be altered if required.
Cranking fuelling is split into two modes the initial batch mode injection (before full synchronisation of the engine has occurred) and the sequential injection modes (after full crank signal synchronisation). These two modes are listed as #1 & #2 in the maps if you are adjusting the cranking fuelling ratio maps for larger injectors make sure to adjust both modes by the desired amount.
There is also a cranking ignition timing 2D map, this map is the base timing used when the engine is in a cranking condition, after the engine starts ignition timing will be referenced from the normal ignition maps (after a short delay).
Idle
The Idle Target maps are available, there are two maps one for idle target out of gear and idle target when a gear is engaged, simply set the values for the desired idle speed.
Map List
Ignition
The Ignition maps are against RPM and Man Absolute Pressure, there are dedicated maps for each Camshaft angle in 10deg steps and there are also maps for VTEC ON and VTEC OFF. There are a series of base, maximum, addition and retard maps as well as many compensations maps to give the finial ignition timing value.
The strategy employed uses a MBT map with a maximum allowable ignition value based on the known knock limit of the engine on a specified octane fuel. This base MBT and the knock limited maps then have corrections added and the knock sensor is used to specify how much of the values in the maximum knock limit maps can be added.
Ignition Calculations and Timing
As previously discussed there are several defining function that the ECU uses to calculate where to set the ignition timing and the three components according to our understanding is a fuel based correction (octane correction), an engine conditions correction and the base ignition timing (MBT MAP). The maps and logging parameters interact roughly as per the image below.
The octane correction function includes the corrections for AFR plus the calibrated Max timing map and knock sensor activity. When you plot the maps out per RPM you will see that the octane correction factor function sum add up to a negative number this value is added to the base map. So for 5500rm the ingition timing output plot looks about like this (Timing Value vs MAP)
After the octane correction has been added to the base map the other orrections and limits are applied and the FINAL timing is then calculatedTo show this using the logging parameters you can see how the maps are shown represented at various points through the calculations.
Here is a simplistic view of the final ignition timing calculation
- Ignition Timing Base (20deg) minus
- Ign Retard Combined (-6deg)
To calculate the Ignition Retard Combined (-6 deg) is calculated as follows:
- Knock Retard (KR) map output is -8deg
- Knock Retard Multiplier is 0.45 KR*KRM
=-3.5deg Knock Retard amount plus
- Ignition Maximum map output is -4deg plus +2deg from AFR Target map so:
-4 plus +2deg = -2deg Ignition Maximum
If there were other corrections applied due to high IAT or ECT these would be applied to the sum of the Timing Base + Ign Retard Combined Final timing
- Ignition Timing Final is 20-16 = 14deg final timing
Tuning the ignition timing can be done many ways, the base map could be changed and this would mean that the ECU will advance as much as possible from the base map depending on the knock sensor output. You could also adjust the Ignition timing MAX map which will effect how much timing can be added to a max but the tuning will have to be done with a KRM value at 1 which can take some time to build up.
If you are tuning a turbo car with much less ignition timing requested than normal, you start by adjusting the axis values to accommodate boost and use the base timing map to do the majority of the igntion changes you could use the ignition timing max maps to effect the amount of correction that is being applied when you start to encounter knock.
Map List
Live Data Parameters
- Ignition Maximum (°) Ign. Maximum map output PLUS the Ignition Addition for AFR Target
- Ignition Retard Combined (°) Combined retard value includes Ign. addition, Advance/Retard & overrun
- Ignition timing (°) Actual Final Ignition timing
- Ignition Timing Base (°) From Timing Base map (MBT map), the Ign. Timing cannot exceed this value
- Ignition Timing Retard (°) Value from Ignition timing retard maps
- Knock Advance (°) Amount of learnt advance from knock calculations
- Knock Retard (°) Output of knock retard map multiplied by knock retard multiplier
- Knock Retard Multiplier (-) The current value of knock multiplier used in knock retard value Knock Sensor Voltage (Volt) Voltage returned from knock sensor
Ignition Timing Base
The Ignition Base map is an idealistic value to produce maximum best torque (MBT). There is a base map for VTEC ON and OFF and for each 10 deg cam angle. There is a logging parameter called Ignition Timing Base that follows the output of this map.
Ignition Timing Maximum
The Ignition Maximum map shows the knock point for low octane fuels. There is a maximum map for VTEC ON and OFF and for each 10 deg cam angle and a logging parameter called Ignition Maximum. Decreasing these values will retard the ignition timing
Ignition Addition Maps
These maps are applied all the time and should be seen as a global addition, There are maps for each 10 deg cam angle but not VTEC ON and OFF. The Ignition Addition maps have negative values but they can be made positive.
Ignition Addition for AFR
The output of this map is added to the Ignition Maximum calculation for a given AFR Target. The values are multiplied for the current AFR Target, using the “Ignition Addition Multiplier – AFR Target” map, so the richer the AFR, the more advance is added. The map values can only be positive values not negative.
Ignition Advance and Retard
There are 3 pairs of ignition advance/Retard maps. They advance the ignition timing from cold and retard it when hot depending on the level of load on the vehicle
Ignition Timing Advance Cold - maps add ignition globally as per the map values in the high or low load map
Ignition Timing Retard Hot - maps remove ignition timing globally as per the map values in the high or low load map
Ignition Timing Retard - Charge Air maps will remove ignition timing globally according to the values in the high or low load map
Knock Control
Knock control in the Honda is used as a fuel octane adjustment to ignition timing as opposed to an instantaneous knock adjustment when improper combustion occurs. The system monitors the knock sensor values and averages them reducing the timing globally to reduce the level of knock sensed. The logging parameters that are relevant to knock control are repeated below.
Knock Retard Maximum
Maps are against RPM and MAP and there are maps for VTEC ON and OFF and are only active under higher load conditions.
The output of the knock retard Maximum maps is then multiplied by the Knock Retard Multiplier (KRM), there is an initial value set but after start the KRM may increase or decrease.
If the KRM is currently 100% then ALL of the Knock Retard value will be added to the logging parameter called Ignition Retard Combined. If the KRM is currently 0% then NONE of the Knock Retard value will be added to the Ignition Retard Combined calculation.
The Knock Retard Initial (KRI) can be edited and is set at 50% by default. If the engine is knocking then the KRM will increase and more of the Knock Retard map will be added to the Ignition Retard Combined calculation
Map List
Live Data Parameters
- Ignition Maximum (°) Ign. Maximum map output PLUS the Ignition Addition for AFR Target
- Ignition Retard Combined (°) The combined amount that will be subtracted from the Ignition Base (includes the following: Ignition addition, Ignition Advance and Retard and Ignition overrun) Ignition timing (°) Actual Final Ignition timing
- Ignition Timing Base (°) From Timing Base map (MBT map), the Ign. Timing cannot exceed this value
- Ignition Timing Retard (°) Value from Ignition timing retard maps
- Knock Advance (°) Amount of learnt advance from knock calculations
- Knock Retard (°) Output of knock retard map multiplied by knock retard multiplier
- Knock Retard Multiplier (-) The current value of knock multiplier used in knock retard value Knock Sensor Voltage (Volt) Voltage returned from knock sensor
Limiters
Rev Limiters
These maps control the engine speed that the fuel injectors will be cut to maintain a set RPM. There are several maps that set the Rev limit in the Honda ROMs and these are used by the ECU when VTEC is on or off, there are other limits (Rev Limits #5-#8 & alternative maps) that are used when the ECU is in different calculation modes. The rev limits use vehicle speed on the first axis but it is recommended to raise only the RPM column and change both values by the same amount.
Speed Limiter - Fuel & Throttle Cut
There are two methods to reduce power at the speed limit these are the value at which either fuel will be cut or the throttle will be closed. The fuel cut value is a simple 1D map, adjust it to the desired value. The throttle cut is a set vehicle speed with a max allowed throttle opening, you could adjust either but changing the vehicle speed column is recommended.
Engine Load Limiter
There are engine load limits that can be adjusted if required, these can be raised if there are high loads created by forced induction installations.
Map List
Load
Like most ECU’s the Honda has a series of calculations that measure or estimate an airflow which is then tuned into an engine load amount (Honda uses mg/stroke) which is then used to calculate a matching volume of fuel depending on the target AFR. The first task of tuning any induction modification is to get the target and actual AFR to match. This is done by calibrating the appropriate maps (MAF Curve or SDVE map) to ensure that the engine load calculated delivers the correct amount of fuel.
There are 2 different methods for engine load determination in the Honda ECU, Mass Air Flow measurement (MAF) and manifold Pressure determined airflow using Speed Density (SD) maps, the exception to this is the JDM region ROMs which only use SD and have no MAF sensor. For Cars that use the MAF sensor in normal operation there is a factory SD map set out to activate during a period of reverberation at particular loads rpm and throttle angles, to counteract this the ECU uses a simple 3x3 map to calculate engine load during this period.
The digital logging parameter called Engine Load Mode will show if the current Engine Load calculation is Honda MAF or Honda MAP based or even RaceROMSD. The choice for which mode for load generation is used is shown graphically below
Live Data Parameters
- Engine Load Mode (Digital) Shows the different load modes use, Factory MAF, Factory SD, EcuTek SD
- Engine Load (Final) (mg/str) The final Engine load used for fuel volume calculation
- Engine Load (MAF mode) (mg/str) The Engine load derived from the OEM MAF sensor calculation
- Engine Load (MAP mode) (mg/str) The Engine load derived from the OEM MAP sensor calculation
Factory SD (Speed Density)
The factory SD mode is used when the following conditions are achieved
- RPM increases above either of the SD minimum RPM map - The minimum RPM required for the ECU to enter the factory SD mode, also consider the map called SD Minimum Throttle Angle
- Throttle angle increases above SD minimum throttle angle map - The minimum required throttle angle for the factory SD to become active
It will remain in the factory SD mode until the
- RPM exceeds the values in the SD to MAF switch RPM threshold - The ECU will switch from SD back to MAF past this engine speed
- The throttle angle or RPM drop to below the thresholds to go into SD mode.
JDM cars run full Time SD, if you are tuning one of these vehicles we would recommend that you use the RaceROM SD calibration method as it will be much simpler to tune. The standard full time SD method interpolates between a series of maps (for each cam angle) that output a value of injector (ms) open time to give 14.7 AFR (lambda 1). This method is very accurate but it takes a considerable amount of time to calibrate each individual map as the cam angle is always changing.
If the injectors are scaled correctly the open time here would give 14.7 AFR, you would need to adjust these values to give the desired AFR if changes that effect the engine VE are made.
Factory MAF
The factory MAF system in the Honda works similarly to any other modern MAF system, if you change the MAF tube size or make other changes that effect the airflow in the intake system you will need to check and if necessary adjust the MAF sensor scaling to suit. If your fuelling is showing 10% too rich (-10% Fuel Trim) you will ned to adjust the airflow value at the corresponding voltage point by approximately half of that value (so 5%), you should recheck the fuel trim/AFR to confirm your change has had the desired effect.
RaceROM SD
We have created a simplified set of Speed Density maps that allow you to calibrate the volumetric efficiency of the engine to deliver accurate and precise fuel delivery and ignition timing. We have Separated the System into two maps. One map which utilizes VTEC ON and one for OFF. Two maps give the tuner more finite control around the VTEC switch point.
To enable RaceROM Speed Density select which map switch modes you wish to enable SD and set the RPM, MAP, MAF and Throttle Angle thresholds to activate as you wish. For hysteresis the top value should be higher than lower value.
RaceROM AlphaN
Alpha N is a method of estimating airflow (and hence engine load) using throttle position as a reference. This method is very useful when tuning cars with multiple throttle bodies (ITB’S) or inlet manifolds with poor MAP sensor reference positions. The Alpha N method can be invaluable if SD mapping cannot give you enough resolution to accurately calibrate the engine. To enable Alpha N load estimation, you will need to enable Alpha N mode instead of Speed Density. We have not specified a base MAP for Alpha N use in the RR patch due to the vast differences in hardware types available, however, if you need further information regarding this set-up please contact EcuTek support.
Engine Load Limits
There are many limits in the Honda control strategy, however the RaceROM feature file replaces these with a simple set of 1D values. If when tuning you are hitting these limits you should increase the values, the upper value is used in map switch mode 1 and counting down map switch modes 2,3,4.
Torque Actual
The torque actual values are used as an output to the automatic transmission (if equipped), there are two maps, one for normal and one for VTEC operation, these may need to be adjusted to improve the shift characteristics of the automatic gearbox.
Sensor Scaling
MAF Sensor
This map can be used to rescale the Mass Air Flow sensor relation between voltage and Mass Air Flow in g/s. Change this value if you have changed the MAF housing or intake system of if your AFR does not match the values in your fuel map.
Map List
MAP Sensor
The OEM Manifold Absolute Pressure (MAP) sensor reads up to 1.55 bar (Absolute), so if tuning a Turbo/Supercharged engine you will need to install a replacement sensor capable of reading higher manifold pressure.
To adjust the sensor scaling you will need to use the scaling data from the manufacturer to set both the multiplier and offset value. Some common multipliers are below.
NOTE: It’s very important that the MAP sensor scaling is accurate when using Speed Density, after fitting and calibrating an uprated sensor a quick sanity check is to view Manifold absolute pressure in live data, with ignition ON (engine OFF), and Map Access running it should read the same as the Atmospheric Pressure parameter.
| Sensor Scaling | Multiplier | Offset |
|---|---|---|
| 1.55 Bar Factory MAP Sensor | .367 | -/05 |
| 3 Bar Map Sensor | .617 | .03 |
| 4 Bar Map Sensor | .825 | .031 |
Air Intake Temperature
This map can be used to rescale the intake air temperature sensor voltage to temperature scaling.
Misc.
Fan Control
The Radiator fan control maps are used to control when the main radiator fans switch on and off. These can be adjusted as required and there is one map for switching ON and one for switching OFF.
Gearing
These maps are used in the functions that interprets vehicle speed setting the current gear and transferring the vehicle speed to the dash. For cars with different gearboxes or final drives these maps may need to be changed. To change what the ECU see as gears use the Gear ration maps 1st – 6th, the values include the final drive ratio and wheel circumference.
As an example for 1st gear, instead of it showing 3.267 (the actual gear ratio), you'll get 8.46, which is
𝐺𝑒𝑎𝑟 𝑅𝑎𝑡𝑖𝑜 𝑉𝑎𝑙𝑢𝑒 = 𝐴𝑐𝑡𝑢𝑎𝑙 𝐺𝑒𝑎𝑟 𝑅𝑎𝑡𝑖𝑜 (3.267) × 𝑊 ℎ𝐹𝑖𝑛𝑎𝑙𝑒𝑒𝑙 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝐷𝑟𝑖𝑣𝑒 𝑅𝑎𝑡𝑖𝑜 (5 .(0631.955) ) = 3.267 × = 8.46
if you have changed the gear ratios you should set the values by the following formula,
Final Drive Ratio
New Gear Ratio value = New Gear Ratio × Tire diameter × π
If you change only the final drive you will need to adjust the values by the percentage difference in final drive ratio as well for all gears. This is simply done by CTRL + P using the difference in ratios.
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