Flex Fuel

Sensor and Wiring

The following Sensors are known to work

GM part numbers

13577379 - SENSOR (short tube)

13577394 - SENSOR (long tube)

13352241 - HARNESS

The Pinout is shown below


Sensor Setup

Connect your sensor to a digital input on the ECU. Then, pick the pin in TunerStudio at Sensors -> Misc sensors -> Flex fuel sensor.

(technical details - we expect a pull-up on the ECU, about 3K, somewhere 1K to 5K)

sensor settings

Fueling Setup

In Fuel -> Injection Configuration, configure Stoichiometric ratio and E100 stoichiometric ratio. Unless you're doing something very weird, 14.7 and 9.0 are the correct values respectively (pure gas has a stoichiometric ratio of 14.7:1, and pure ethanol 9.0:1).

That's it! The firmware will now automatically vary the fuel's stoichiometric ratio based on ethanol content.

It's recommended to switch to lambda mode (File -> Vehicle Projects -> Project Properties -> Settings -> Lambda Display), as the target lambda table is multiplied by the current stoichiometric ratio to get the target air/fuel ratio.

injection settings

Ignition Timing

Coming soon...

Boost Control

Coming soon...