Every DEFI tune comes with two complete maps: one for your pump gas and one for E85. They live on your device, and you flash the one that matches what is in the tank. Here is how that works, and how to choose.
How switching works
Each map is a complete calibration. Both sit in the TDN app for your vehicle, and you choose which to write to the car. Switching is a re-flash from your phone, not a button on the dash — so you switch when you change fuel, not halfway down a straight.
If you want the car to adapt by itself to whatever is in the tank, that is a flex-fuel calibration. It reads the ethanol content from a sensor and blends between the two. The sensor has to be fitted and the fuel system has to support E85 — we write the calibration; we do not supply or fit the hardware.
Pump gas: the everyday map
Written for the octane you actually buy — 91 in California, 93 where it is sold. It is the map for commuting, road trips and anywhere ethanol is hard to find.
E85: the honest trade-off
Higher ethanol resists knock and cools the charge as it evaporates, which is what lets the timing come up. It also costs fuel economy, asks more of the fuel system, and is not sold everywhere.
There is a quieter argument for it too. A blend that makes a little less peak power than full E85 but keeps the engine well inside its knock margin is easy on the motor. Which one is right depends on the car and what you do with it, and we will tell you which we would run.
Race fuel and more maps
A race-fuel map is written to one specific fuel, not a category — tell us exactly which one. It, or a map for each pump octane if you travel between 91 and 93 states, is an additional map added when you configure the tune. We keep Ignite E85, E90 and E98 at the shop, collected over the counter in Corona.
Questions people ask
- Are the pump-gas and E85 maps both included?
- Yes. Every DEFI tune includes a complete map for your pump octane and one for E85, at the base price.
- Can I switch maps while driving?
- No. Each map is a full calibration you write from the TDN app, so you switch when you change fuel. If you want automatic blending, that is a flex-fuel calibration with an ethanol sensor fitted.
- Will E85 hurt my engine?
- Not by itself, if the fuel system can supply it and the calibration is written for it. It needs roughly a third more fuel volume than gasoline, which is why the fuel system matters before the map does.