APR Ethanol and Race Fuel Maps
Switching from a lower octane fuel to Ethanol or Race Fuel
Running Ethanol and Race Fuel maps with lower quality fuel can and will destroy your spark plugs and potentially your engine. Please follow these instructions when switching from a lower octane map to a higher octane map.
- Drain the gas tank of all fuel and then fill the tank with the higher octane fuel.
- Allow 15 miles of driving before switching programs. Typically, lower quality fuel will remain in the fuel lines and fuel rails for quite some time before it’s all removed and replaced with the new, higher octane fuel. This is ever more so true on vehicles that have both port and direct injectors. This is even true if you’ve pumped out your gas tank, or idled the engine until it stalls out due to an empty tank.
- During this 15 mile cruising period, if you’ve filled up with Ethanol, do not go wide open throttle. Ethanol is dramatically different than normal pump fuels, but will operate fine if you cruise lightly. Also, if switching to Ethanol, you may get a fault for fuel trims out of range. When this occurs, clear the fault code, switch to the Ethanol map, and continue driving lightly.
- When you’ve driven lightly for 15 miles, switch maps to the higher octane fuel map and drive a few miles before going wide open throttle.
- If you detect any hesitations, timing pull, audible knock, etc, let off the throttle immediately! You may still have lower quality gas in the fuel lines.
Race Fuel Info
APR only recommends using Sunoco GT260 for 100 octane (R+M)/2 maps and Sunoco GT260+ for 104 octane (R+M)/2 maps. Unless specified otherwise, only use these types of fuel as other types of race fuel may have unintended behavior.
Ethanol content varies dramatically. A pump labeled for E85 may have content from 85% all the way down to 51% depending on season and location in the USA. This may be different elsewhere in the world. Most non-flex fuel E85 maps only have an operating range of E60-E85 (always confirm the operating range on each product page). Do not use ethanol content lower than specified by the map. Likewise, do not use ethanol content higher than specified by the map, as the system may be fueling limited and unable to run the higher ethanol content. For these reasons, APR highly recommends using an Ethanol Content Sensor to monitor content levels.