After changing the final drive gearing on my Daytona 675, I wanted to recalibrate the speedometer as the sprocket changes caused it to overread by 10%. This is achieved by simply changing parameters in the bike’s ECU (Electronic Control Unit aka the “brain” or engine management system). You might also need to change engine parameters after changing the exhaust system as the new one will probably require a different fuel map.
Changing the engine map stored in the ECU sounds scary but if you’re careful and follow the basic instructions, then the process is actually quite straight forward. Normally this sort of thing can only be done by a dealer with specialist tools. However a clever individual has created a piece of software called TuneECU which allows you re-map the ECU for various makes and models of bike. Not only is this software perfect for modders, but it’s available for free too! To see if it works for your bike, visit the TuneECU website.
Please read the TuneECU manual in full before attempting to modify your engine map. You use any information from this post entirely at your own risk! I do not accept any responsibility for any damage you cause to your motorcycle or engine. You have been warned!
The only requirements for using TuneECU are Windows XP or Windows 7 and an ODB-USB cable. I personally use TuneECU with Windows XP running under VirtualBox on my Linux laptop. This trick also appears to work for Mac users too. Apart from installing and running the TuneECU software, the only other thing you’ll need is an ODB II to USB cable. This should be a VAG (Volksvagen/Audi Group) compatible cable – mine came from Amazon marketplace and cost less than £10 (US$16).
I’m not going to go into the specific details of how to install TuneECU or the cable’s drivers on Windows as there are plenty of instructions including these on the TuneECU site. If you have the cable, then this is an overview of what you need to do before you can use start to use TuneECU:
- Either install the cable drivers that came with your cable, or download and install the correct drivers from FTDI Chip website
- Make sure your Windows computer is disconnected from the internet BEFORE you plug the cable in for the first time, so that Windows cannot try and locate drivers for you. You MUST use the ones that either came with your cable or which you downloaded in the step above – don’t allow Microsoft to install its default drivers! During the install, when prompted select the folder containing the driver and install those files
- Once the FDTI driver is installed, you can safely allow your computer to re-connect to the internet
- Now download and install TuneECU. I suggest installing it in its own folder on your C: drive. On my setup I have a folder c:\TuneECU – this folder contains the TuneECU.exe application and one DLL
- Create another folder on your C drive which you will use to store your bike ECU maps. You can either download (read) these from your bike’s ECU or download alternate maps from the internet
TuneECU and Engine Maps
TuneECU allows you to read the map from your bike, to make changes to a map (loaded in memory) and to save maps to disk for later re-use. You can download more maps for different exhaust/exup combinations from Tom Hamburg’s website.
The ECU map doesn’t just containing the engine air/fuel ratios at different throttle positions and RPM. It also contains details of any of the other parameters that you might want to modify such as whether to enable or disable the EXUP or SAI valves for example. This is why changing even one simple parameter requires you to download the complete map back into the bike’s ECU, despite the fact that no fuelling information was changed.
It is always advisable to read your bike’s current map and save it to your computer BEFORE you do anything else. This way you’ll be able to revert to this map if you make a mess of your settings and find that a new map downloaded from the internet doesn’t work as well as your previous one.
Locate your ODB-II Connector
The ODB-II connector on most Triumph motorcycles is a loose lead that is located under the seat towards the back of the tank. It usually has a plastic boot/cover on it and can be secured on a male connector/holder. Pull the connector free and connect your ODB-II lead when required to do so.
Reading the bike’s ECU map
When you first launch TuneECU, disable the Auto-Connect option on the Options menu. These are the steps that you then need to take to read the map from your bike:
- Either pull out the headlamp and tail light fuses, and (if possible) connect a second 12V (car) battery in parallel with the existing bike battery. The ECU is very sensitive to a voltage drop and may abort a read or download operation mid operation otherwise. If you have a fully charged and healthy battery and pull those two fuses before you start, you should be OK even without a second battery connected
- Turn the bike’s ignition on but do not start the bike
- Select the Connect option from the ECU menu in TuneECU. Wait until the flahing lights at the bottom of the TuneECU window go from red to green – this indicates that TuneECU has connected to the ECU correctly
- Select the Read Map option from the ECU menu. This will read the bike’s map into TuneECU’s memory. Be advised that this operation can take around 10 minutes or more. Make sure your computer doesn’t go to sleep during this operation
- Once the map has been read, use the Save Map File option on the File menu to save the .hex map file to your computer. Congratulations! You now have a backup of your bike’s ECU map saved to disk
- If you do edit this map, make sure you save the modified version under a different filename from your original one!
Installing a New or Modified Engine Map
Installing a new map into the bike’s ECU is simple.
- Launch TuneECU and open one of your (.hex) Map files stored on your computer
- Connect TuneECU to the bike (using the same steps as above if you’re not already connected, making sure the bike’s headlamp and tail light fuses are disconnected to preserve the battery)
- Select the Download option from the ECU menu. This will download and install the current map opened in TuneECU to your bike’s ECU. The download operation takes about 2 minutes
- Select the Disconnect option from the ECU menu to close the connection to the bike ECU
- Turn the bike’s ignition off and then replace the headlamp and tail light fuses
- That’s it! Unless the new map you downloaded changed any of the bike’s fuelling information in which case you will need to take the following steps to reset the ECU adaptation:
- Connect TuneECU to your bike (using the same steps as above) this time with the headlamp an tail light fuses connected (otherwise the bike won’t start when need later!)
- Switch to the Tests pane (near the top right of the window) in TuneECU
- Select the Reset Adpation option from the ECU menu and wait about 30 seconds for the operation to complete
- Start the bike engine (with TuneECU still connected) but DO NOT TOUCH the throttle!
- Allow the bike to idle until the fan kicks in and then continue to idle until the TPS indicator at the bottom of the screen goes green or 15 minutes has elapsed. If the indicator doesn’t go green after 15 minutes, don’t worry, just continue with the following steps below anyway
- Disconnect TuneECU using the Disconnect option on the ECU menu
- Switch off the bike and disconnect the cable
Recalibrating your Speedometer
TuneECU allows you to recalibrate your speedo by adding or subtracting a percentage amount to the speedo parameter. If your speedo overreads by 10% then you would need to adjust the speedo reading by -10% (minus). If your speedo underreads by 5% then you would enter +5% as the speedo adjustment parameter value.
Adjusting the speedo reading is normally required when you change the gearing on your bike. I changed the gearing on my Daytona by going down one tooth on the front and up two teeth on the rear in order to get quicker drive out of the corners. You can read more about this in my post on gearing changes.
Open TuneECU and make sure it has the current map for your bike loaded. Click on the Speed Adjust (%) parameter near the bottom left of the Map Edit tab. A set of up/down arrows will appear – you use this to set your speedo adjustment value.
Once you’ve made your change, save your modified Map (.hex) file back to your computer (preferrably under a new file name). Then follow the instructions (given above) to download the modified map into your bike’s ECU. Provided you didn’t change any of the fueling parameters, then your won’t need to reset the TPS adaptation. Your speedo will now be corrected by the amount that you specify.
Note that adjusting the speedo also adjusts the odometer (mileage recorder). The two are linked and there is nothing you can do about this. When adjusting your speedo, bear in mind that the speedo typically overreads by about 6% from the factory so that the manufacturer won’t be sued by you when you get a speeding ticket! You might want to bear this in mind and factor it in when calculating your adjustment percentage.
When I made my sprocket changes, I reduced the top speed of the bike by 10%, so that is the amount that I adjusted the parameter by. After downloading the map back into the bike’s ECU, the speedo was correctly re-calibrated without the need for a SpeedoHealer.