Beginners Start-Up & Tuning Guide




This is a brief and basic how-to to get you started using Crome, making a basemap and the basic fundamentals of beginning to street tune your own vehicle.  I assume a lot about you, the user of this software before starting along this path.  Please use this as a GUIDE and do not email or message me technical support questions about this guide unless you have purchased a Crome PRO Package from me please.  Crome is not my product nor do I necessarily support it in a technical nature.  I do support it as an enthusiast and as a vendor of hardware products that people use on a daily basis in conjunction with Crome through my posts on various forums when I can.


Please consider using Crome PRO in your next Honda/Acura project for DIY ECU Tuning.  See more information at:


Crome Setup, COM Ports, Wideband, etc


I have developed a basic write-up located here:


Setup Guide


I will assume you have everything set and operating properly before beginning.


Version Info


Please make sure you have the latest stable version of Crome software when attempting this.  I am using Crome PRO beta 1.2.5 with Adv Boost tools (ABT 2.0+) and FV Fuel Tools (FC5) that can be found on the PGMFI forums in these threads:


Crome Beta 1.2.5

Advanced Boost Tools

FV Fuel Tools


How Do I Make A Basemap for MY Vehicle?


Well…you want to start off with the best possible basemap for your setup right?  Who wouldn’t…so you need to model your basemap as closely as possible to the stock maps for your engine as possible.


Where Do I Find The Stock Maps For My Vehicle?


This is a common question and the answer is always RTFW (read the fucken Wiki).


Wiki ECU Definitions Codes and Stock ROM Dumps


Go there and look for the CLOSEST OBD1 .BIN file that matches your motor setup.  It is very easy if you have a B18b1, B18C1, D16Z6, D15B stock USDM motor.  It may get a little tricky if you have a JDM, EDM or other motor that isn’t typically found.  Also, some motors are OBD2 and only have OBD2 ROM dumps but luckily Crome does have the ability to open some OBD2 ROMs.


So download the .BIN file that closely matches your motor.  In this example…we are going to use the following common setup to make a basemap for:


- B18C1 GSR motor (Skunk2 IM, no IABs)

- DSM 450cc Injectors

- T3/T4 Turbo


…so we need to download the OBD1 273 Code Dump


Save it as ‘StockGSROBD1.bin’ on your desktop.


Now open Crome and click on the icon  to open a new ROM.



Choose the P30 JDM Civic B16A (203) and click OK.  Your screen should now look like this:



Notice the ‘Base P30’ in the bottom left hand corner of the screen…we are using ‘P30 CODE’ as it is the most ‘developed’ code for OBD1 and Crome.  P72 is highly supported as well.  Start with a P72 codebase if you plan on using IABs (secondary butterfly valves) with your GSR or H22 motor/intake manifold.


Now open another copy of Crome and open that 273 GSR Bin we downloaded.  It should look like this:



Notice the BASE P72 code in the bottom left hand corner.  Also notice that the RPM scalars (rows) and LOAD scalars (columns) are different between the P30 and P72 maps.  We need to change this on the P30 code to match the P72 scalars so we can effectively copy/paste the GSR maps into P30 code.  You will need to do this for Low Cam and High Cam, Ignition and Fuel Maps. 


***SPECIAL NOTE:  The newest version of Crome has enhanced importing/exporting of maps and scalers.  Although I haven’t tested it personally, I hear it works pretty well and may cut out a few steps in this process.  I recommend you go through the step by step procedure and first learn what is happening when creating your own map and then go back and try Crome’s import/export feature and see how closely they match up.


I generally overlap the two open Crome programs to make it easier to see what needs to be edited.


You CANNOT edit the column headings for the first and last columns in a ROM.
You CANNOT edit the row headings for the first and last rows in a ROM.



Double Click the scalar you want to change and type in the new number.



When you are done, the row and column scalars should match on the Low Cam



…and the High Cam



Now you are saying, ‘wait, Chris…the High Cam map is all screwy and are different sizes from each other.  What should I do????  Whoa is me….L


Not to worry…for this particular case (adjust on a case by case basis) we are going to copy and paste in ONLY the rows that match.  LOW Cam is easy, select the WHOLE map since both are the same size…10x20, copy from the P72 ROM and then paste into the P30 ROM.


P30 Low cam with GSR Maps…



For the HIGH Cam, you need to select the ROWS that can be copied over…



You can see here that I copied over a 10x14 block of cells from the GSR to the P30 code…and then I copied the same 0 row from the GSR file to the first six rows of the P30 code as your motor really will NEVER run in this section anyways unless for some odd reason your GSR is a freak with a very low VTEC point J


Now you have a P30 Bin file with GSR maps…save the file here in case you ever need to start over.  Save it as something like StockGSRmap-P30code.BIN.


Setting Up the ROM Options


Next is a process that I have found a particular order that works well for me…not everyone will use this order and you may find your own method after a while.  Please follow this step by step if you plan on using my process.


First, always disable the Checksum and add Datalogging under the plugins.



Next Hit ‘F4’ and set your options based on the ECU you are using.  If this chip is going to be run in a P28 ECU and there is a perfectly working O2 sensor, the your options should look as follows:



As you can see, I have checked off only the KNOCK sensor disable, changed the rev limiter, idle, VTEC and speed limiter.  This is just an example…use whatever fits your setup best and don’t just copy my settings…they may not be right for you.


At this point, you have a very nice BIN file that you can throw in any P28 or OBD1 VTEC USDM ECU that will operate a GSR fairly well.  Not as well as say a STOCK P72 ECU but very well none the less.


WHY isn’t this IDENTICAL to a Stock ECU?


For a number of reasons, this BIN file will not run identical.  #1 is because this is modified code.  Things have been changed with plug-ins like datalogging that are different than stock code.  You can’t take non-Stock code, throw stock maps into it and expect it to run identically.  Idle control is setup differently between various codebases and will run slightly oddly in a different ECU with a different codebase.  These are just two examples, because I am not a ROM code expert though…I don’t know all of the little intricacies that affect how the car will run.  I just trust that with tuning, I can get the car to run as I wish (which generally happens).


Adding BOOST


Use the Advanced Boost Tools plugin to add Boost to your ROM:



Go through the wizard, for this example, choose the 1.7 Bar Honda MAP sensor with 6 Boost Columns and then keep clicking Next.  You will now see new tables:



Notice that all the row values are exactly the same in columns B11 – B16.  No values have been set…this is the next part of the process.


Click on the  icon or hit CTRL+B to bring up the Adjust Boost Tables wizard:



For the purposes of this write-up, just use the default settings as they are safe and will work.  As you get better at this and get more experience, you may tweak this part of the process as well.


***SPECIAL NOTE:  I now generally use a much more conservative approximation when I setup boost tables.  Start with 1 degree for B-Series motors and 1.25 degrees for SOHC motors.  In ‘turbocharger efficiency I start with 180% for Turbo motors and 220% for Supercharged.


Your maps will now look different and less uniform:



Take a look at all 4 maps, high/low/fuel/ignition and see the changes you have made using Crome’s built in calculators J


The latest version of Crome now has enhanced 2D and 3D viewing modes of the maps, be sure to get used to looking at maps using these (especially 2D).


Remember to save again…perhaps using a different name such as GSRmaps-P30code-boost.BIN.


Adding Fuel Tools


Fuel Tools is a recent plug-in addition that makes tuning vehicles using non-Stock Injectors MUCH easier.  I recommend you use in even on vehicles that are using stock injectors if other parts of the setup are highly modified.



Add Fuel Tools and then move on.


Adjusting for Injector Size

Click on the  icon or CTRL+F to bring up the Fuel Multiplier screen:



Because we are using 450cc injectors, you need to put 450 in the New Injector Flow Rating…notice that the adjusted multiplier has changed to .533.  Click on the Advanced Tab and continue…



Fuel Tools 2.0 allows you now to store your fuel multiplier value.  This multiplier takes the numbers in the Fuel Map and applies this multiplier to them before the ECU does its final Injector Pulsewidth calculation and squirts fuel into the motor.  This fuel multiplier is powerful because motors generally have a shape or a curve to them, and when we change injectors, the motor stays the same so the curve should stay the same (figuratively).  Different brands of injectors will have different properties that will slightly change this curve though which is also why that OFFSET box is now there…this will be explained further in a moment.


With larger injectors (than stock), we must also modify how the motor cranks, starts and adds fuel when the throttle is depressed (Tip-in).  O2 sensor trim can be modified as well but on most tuned vehicles, we aren’t enabling the O2 sensor so I will not go into that option box.  You will find the numbers you enter in these boxes depend highly on the injectors but will also be affected by cams, throttle bodies and even things such as how strong your alternator or battery are as well.  You must TUNE these boxes…don’t just set them and leave them.  It is all a part of a large process.


CRANKING is the extra fuel the ECU injects into the motor as you try and start the car.  When the motor is cold, the ECU will throw in more fuel than when the motor is hot (warm start or cold start).  This multiplier affects both of those.  The reason we change (or lower) that number for larger injectors is because with a stock program the ECU still thinks there are 240cc (or similar) injectors there and will pulse for that size injector.  If we double the size (when using injectors like DSM 450cc), the ECU will be shooting in twice the fuel which is WAY too much and could flood the motor.  We need to lower (a number smaller than 1 which is STOCK) so that the ECU doesn’t flood the motor at start-up.


POST STARTUP is the extra fuel the ECU supplies to the engine for approx 5-20 seconds (depending on the temp of the motor) right after the motor starts.  This again is another setting the stock ECU thinks is for 240cc injectors.  Using a Wideband, see what number gets your Air/Fuel ratio to be stable and not overly rich for the first 5-20 seconds after start-up.


OFFSET is an additive multiplier that applied to the Battery Voltage Offset tables.  This number in combination with the Final Fuel Multiplier value is critical to getting the maps extremely close from the start, as well as proper idling properties.  When you first start the car on the basemap, use these two values only to get the car to start and idle properly before changing ANY of the fuel values in the maps.  Use whole numbers in the offset box but understand that what you are doing is adding a pulse of the number you add times divided by 100.  For example, we added 45 to our offset box to start, which means we are adding 0.45 to our battery offset tables.


Use CTRL+L to open the Advanced Table where we can find our injector battery offset tables:



That 0.45 we are adding gets applied to each of the 7 adjustable boxes you see above.  So in our example, at the 13.9 volt battery table spot, our pulse is 0.47 + 0.45 for a final 0.92 which effectively ADDS fuel.  The various injector brands at the right have been put into this plug-in by PGMFI ‘Nate’ and they are copied over from AEM’s tested battery offset tables.  They are a good starting point to choose from but in my experience they are set too low and depending on the injector you are using, you will need to add anywhere from a 12 to a 85 offset in the Advance Tab of the Fuel Multiplier window.


See how it changes the curve of the battery offset table when we select the ‘Blue Top’ DSM 450cc injector type:



Every different brand of injectors will have a varied battery offset curve.  Tuning this table is EXTREMELY important when it comes to tuning larger (1000cc +) injectors.  Tuning this table will also become vary apparent to its importance if you run across a car with a bad battery or bad alternator.


Click OK in all windows and once again see that your fuel maps have changed again (color and appearance mostly, the numbers in the boxes will NOT change)…tune these Fuel Tools multipliers and injector battery table meticulously to achieve the best possible results.



Here is where the basemapping portion ends and the theoretical tuning begins.


Basic Tuning with Crome Pro


Because I am at home, sitting in my underwear on the couch typing this…no actual tuning screen shots will take place.


Tuning effectively requires Crome Pro, a Wideband, a Datalogging Cable, and either a Chip Burner w/ chips or the Ostrich Realtime Emulator.


First, set up your target Air/Fuel ratio maps to your desired numbers by hitting F10.



Burn the basemap you just created to a chip or upload via the Ostrich to the ECU.  Turn the Key to the ‘ON’ position and listen for the fuel pump to prime and watch to make sure the CEL light shuts off before starting the car.  If this doesn’t happen, cycle the key once (turn key off and back to the on position).  Once everything is good, start the car and begin real time logging within Crome Pro and watch the wideband readout.


Let the car become fully warm before making ANY changes if it will idle as is.  If the car is overly RICH or overly LEAN and will not stay running, play with the Main Fuel Multiplier and OFFSET boxes to get it to stay idling and running as nicely as possible.


As the car sits and idles, note what the wideband reading is.  If it is running leaner or richer than desired…go back to the Adjust Fuel Multiplier (CTRL+F).  Under ‘Advanced’ adjust the multiplier closer to 1 to richen the mixture or farther from 1 to lean out the mixture.




If you are using the Ostrich and have Real Time Updates turned on, you will notice an IMMEDIATE difference in the AFRs.  If you are burning chips, it is a longer process but the results will be the same.


Keep adjusting the Offset & multiplier one way or the other until you reach your desired AFRs at idle…most people shoot for 14.7 or so but you may be able to nicely idle the car at a leaner mixture which will promote better emissions and less fuel consumption.  Now that your idle is dialed in…the rest of the fuel maps will typically fall somewhat in place to an extent.


Go driving and start logging…try to get readings column by column, filling only one target column at a time.  Tune very broadly and gradually…by column or by row to get the A/F ratio close.  Once that is roughly dialed in, use the Auto-Adjust Maps capabilities and Live Auto-Adjustments of Crome by driving around and making changes.  Make sure to save often and make very small changes.


***SPECIAL NOTE:  I only condone using the Auto-Tune (Live Auto-Adjust) functions of Crome if you are tuning by yourself as it is extremely dangerous to drive by yourself and make adjustment.  I also only condone its use to get you CLOSE to your desired AFRs and only in the part throttle sections of the maps.  Do NOT autotune any boost portions or high low sections of your maps.  Instead make small trips, logging while driving and carefully watching your gauges for safe readings.  Then either take the car home or park in a safe spot to personally analyze these logs and make changes yourself.  It is always best to tune on a DYNO and with one person driving and the other tuning.


Once Auto-Tune has done a decent job of part throttle tuning…use the Create Boost Table Adjustments (CTRL+B) to tune in your Boost AFRs.  Do a pull and log your numbers…or have someone drive while you do the tuning.  Depending on how rich or lean your numbers are (if you see lean, let off immediately), you can adjust your ‘Adjust for Turbocharger efficiency’ numbers down from the 180 you set earlier.



Do another pull and note your AFRs.  Adjust this number lower if too rich and higher if too lean.  Continue doing this until the AFRs come fairly close to your target and then fine tune from there via individual cells.


This will get you very close…nick pick and play from there. After your maps are nice, you can fine tune your other multipliers such as O2 correction, Tip-In and Start-Up. 



You can also tune some of the advance tables that are working correctly at the time of this writing such as ECT and IAT tables.



Options and Setup


Click on ‘FileàSettings’


Here are my tabs…feel free to copy but please experiment for what works best for you.



I don’t use Dynotools so I didn’t include that tab.


Please feel free to post a link to this article on any sites that may benefit from it.  I would also love any critiques or suggestions that could make this write-up better.


Again, please direct any technical questions or issues you cant overcome to the Crome Support Forum on




Chris Harris (XENOCRON)


If you have benefited from this write-up or from anything that I have or PGMFI have created to make your project better, please send a Donation to PGMFI via Paypal.


Additional Info


CROME ------ Keyboard Shortcuts (Randy Schoener)

Original Posting on PGMFI

Save = Ctrl+S
Open = Ctrl+O
Open Existing ROM as New =Ctrl+N
Close Current ROM = Ctrl+W
Refresh Screen = Ctrl+(F5)

SelectAll = Ctrl+A
Copy Selection = Ctrl+C
Paste Selection = Ctrl+V
Delete Selection = (Del)
Undo Last Change = Ctrl+Z Useful when you screw up.
Redo Last Change = Shift+Ctrl+Z
Increase Selected Value = Ctrl+Up Based off configuration under settings
Decrease Selected Value = Ctrl+Down Based off configuration under settings
Selection Adjustments = Ctrl+J Use to Set specific %, +, -, or Value.
Interpolate Selected Values = Ctrl+I Based off configuration under settings
Smooth Current Map/Table = Ctrl+M Based off configuration under settings

Note: All of the above is available from a (Right Mouse Click) in Window.

View Tables = (F2)
View Graphs = (F3)
View Options = (F4)
Show Low Cam Ignition = (F5)
Show High Cam Ignition = (F6)
Show Low Cam Fuel = (F7)
Show High Cam Fuel = (F8)
Show Ignition & Fuel Tables = (F9)
Show Estimated Duty Cycle = Ctrl+(F9)

Show Target Lambda = (F10)
*Show Lambda Reading = (F11)
*Show Lambda Differential = (F12)

View/Add Notes to ROM = Shify+Ctrl+N These notes are written to the end of the ROM file. As long as you are burning to a 32k chip, these notes will not affect your program.
Real Time Programming = Shift+Ctrl+R
*Live Tuning = Ctrl+T
Command Line = Ctrl+K


I offer Street and Dyno tuning at a shop in Clifton or Bloomfield, NJ


Xenocron Tuning Solutions

PO Box 412

Ringwood, NJ07456



Contact me if you would like to setup a tuning appointment or would like to stop by and possibly get started using Crome.


If you need to find a local tuner near you use the Crome Tuner Directory


Copyright 2006 Xenocron Tuning Solutions, Inc.

All Rights Reserved