Configuring your tune for multiple Ethanol percentages via map switching

This will outline how to set up your current (our future) tune for correctly using different ethanol percentages.

First order of business is to setup and install your Ethanol percentage sensor hardware as I outline in this thread.

While using an actual ethanol sensor as linked above is currently the most accurate way to do this, you can also loosely figure out Ethanol percentage by using the analog math way with this handy chart below:



I highly recommend using hardware as you will know exactly what percentage of Ethanol is currently in the car instead of doing math and guessing.

Now, if you did either of the above, you have an Ethanol mixture in your Fiesta ST. The ECU in the Fiesta ST is very powerful and sophisticated and it will be able to handle about up to 30% Ethanol without any software changes by using fuel trims to compensate. HOWEVER, it's better to set some parameters in the ECU so that the fuel trims don't have to work as hard to compensate. This will make the car drive smoother and have smoother power delivery, better gas mileage and better peace of mind knowing the ECU is changed to run correctly.

In order to do this, you *must* have a COBB Accessport and also you *must* have COBB Accesstuner Race software to make any changes to your tuning.

Below I will outline how to make some changes via Accesstuner Race. These instructions are how to setup the BASE LEVEL of software changes in order to have the fueling system setup for various levels of Ethanol percentages. Again, this is the BASE LEVEL. There are more advanced software changes you can make that will allow you to FULLY take advantage of the Ethanol and make more power. I will outline these at a high level after showing how to set up the base level.

Setting up Accesstuner with base level fueling table changes:

1. Open COBB Accesstuner software
2. Load your current tune. I am using the COBB Stage 3 91 octane tune for this example.
3. Once you open your current tune in Accesstuner, the screen should look like this. Locate the "Switchable Maps" folder in the table list on the left:



4. Expand that folder by double clicking on it. Then expand the "Configuration" folder by double clicking on it. It will look like the screenshot below:



5. Select the "Active Map Slots" table within that folder. The table value will be on the right in the black space and you will change the number in this table by either hitting "E" on your keyboard to edit the table or the "+" or "-" key to increment the number up or down. You want to change this value to 4 as shown in the screenshot below. This enables 4 switchable maps. The reason we want 4 switchable maps is for, E10 (normal gasoline), E20 (20% Ethanol) E30, (30%) and E40 (40%).



6. Next, select the "Configure 5-way Desired Fuel Target (Power Demand) table and set this value to 0 to disable it. This will make the ECU run one Fuel Target table for ALL of the switchable maps. Remember this is for setting up basic Ethanol switching. More advanced tuning will enable this and will allow separate Full Target tuning for each switchable map slot. For now, set this to 0 as show in the screenshot below:



7. Now select the "Configure 5-way Fuel Scalar Stoich. Setpoint" table and change the value to 1 to enable it. This allows us to set the correct fueling scaling for each Ethanol percentage mixture in each map slot. After setting this to 1, it should look like the screenshot below:



8. Next you want to go down the Configuration list and make sure all the other Configurations are set to 0 and disabled. I have no screenshot for this but it is pretty straightforward. After you have completed this, pat yourself on the back because you are now done with the configuration portion of this.

9. Under the "Switchable Maps" folder, located the "Switchable Map 1" folder and double click to expand it. Next locate the "Fuel Scalar Stoich. Setpoint" table and select it. This is your first switchable map and for this example, it will be used for regular gasoline . If you are using gasoline that already has 10% Ethanol in it (most gas in America) then you want to make sure the value in this table is set to 14.08, as shown in the screenshot below. If you are using gasoline that DOES NOT have Ethanol already in it, you can set this value to 14.64.



10. Locate the next switchable map folder, named "Switchable Map 2" and double click to expand it. You are going to be doing the same thing as outlined in step 9 above. Select the "Fuel Scalar Stoich. Setpoint" table and change the value in this to be 13.51. This Switchable Map is for E20, or 20% Ethanol. It should look like the screenshot below:



11. Now locate the "Switchable Map 3" folder, double click on it to expand and select the "Fuel Scalar Stoich. Setpoint" table and change the value in this to be 12.95. This Switchable Map is for E30, or 30% Ethanol. It should look like the screenshot below:



12. Now locate the "Switchable Map 4" folder, double click on it to expand and select the "Fuel Scalar Stoich. Setpoint" table and change the value in this to be 12.38. This Switchable Map is for E40, or 40% Ethanol. It should look like the screenshot below:



13. Save this file, load it up on your Accessport and flash this file to the ECU using the Accessport. Congratulations, you are now setup for up to E40 Ethanol mixtures. Depending on your current mixture in the car, you can switch to the appropriate map and since we mapped each switchable map number to an Ethanol percentage, it will be easy to know which map to switch to as the numbers on the tach of the car (during map switching) correspond to each Ethanol percentage. Example: 1,000rpm = Gasoline, 2,000rpm = E20, 3,000rpm = E30, 4,000rpm = E40.

You're done with the basic setup!

Now, let's take this one step further and take some more advantage of those Ethanol mixtures to make even more power! The following will show you how to setup the ECU to add additional ignition timing for each switchable map.

*DO THIS AT YOUR OWN RISK*. Again, this is the base level of additional changes for Ethanol and for this example I am using the COBB Stage mapping for an example. It runs a fairly soft ignition timing curve in it's tuning and adding some additional ignition timing is fairly safe. If you are custom tuned by somebody else, discuss this with your tuner first!

1. Locate the "Switchable Maps" folder in Accesstuner. Double click to expand and then locate the "Configure 5-way Ignition Timing Offset (Base) table. Change the value in this table to be 1 to enable it, as shown in the screenshot below:



2. Locate the "Configure 5-way Ignition Timing Offset Strategy" table and change the value to be 0, to enable 1D table strategy (instead of the more advanced 3D strategy). Your screen should look like the screenshot below:



3. Now, for EACH OF YOUR SWITCHABLE MAPS folders, locate the "Ignition Timing Offset (Global) 1D Load Min." tables and set the value in this table to be 1.500, as shown in the screenshot below. Do this for each switchable maps 1-4. What this does is set the ECU to only use our additional ignition timing once the car is ABOVE 1.500 load, or basically once the car is in boost at WOT. That way when you are just driving normal, the additional ignition timing is not used. Again, this is base tuning for Ethanol. More advanced tuning can change this as well and I might do a write up about that in the future.



4. Now, for EACH OF YOUR SWITCHABLE MAPS folders, locate the "Ignition Timing Offset (Global) 1D" tables and set this to how much ignition timing you want to add. My suggestion would be to change this value to 1 for your E20 switchable map, set it to 2 for your E30 switchable map and set it to 3 for your E40 switchable map. The screenshot below shows a value of 1 for Switchable Map 2, which would be E20. For your Switchable Map 1, which would be normal gasoline, this value should be 0.



Be very careful of adding too much timing. My suggestions work fine for the normal COBB stages for each percentage of Ethanol. Be sure to load this file to your accessport and flash to the car to take advantage of these changes.

More to come!