Subaru CAN Flex Sensor Setup
- Brandyn Mowat
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The following article is for a Euro 08 STI but can be applied to other Subaru CAN vehicles. When purchasing an Ethanol sensor for flex fuel on a Subaru CAN car you must use a unit with a 0-5V output. There are many popular 0-5V output sensors available and EcuTek have used the Zeitronix unit for testing in-house.
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The sensor output is usually a frequency signal but the the ECU can only see a 0-5V signal as an input, if the sensor does not directly output a 0-5V signal a controller or gauge will need to be used to translate the sensor output into a signal usable by the ECU. Below you can see what the gauge and sensor look like (courtesy of Moto East).
Each kit will have its own sensor installation guide so refer to the manufacturers manual for installation specifics. Once the sensor and controller / gauge have been installed the 0-5V signal (from the Zeitronix control unit in our testing) needs to be wired into the factory loom this can be done using pin 3 of the rear O2 sensor plug (T6 - 3). You could also go to the ECU connector B135 pin 4.
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The sensor / controller power will need to come from an ignition sourced 12 V you may be able to use the main relay 12V from Pin 2 of the rear O2 sensor plug if required. Once this is done you will need to disable the Rear O2 sensor correction as well as any DTC's related to the sensor.
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Set up the FlexFuel Ethanol Content sensor in the Sensor scaling tree with the correct input (see link for more details)
Then simply enable Flex Fuel
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After that the fuel quantity and adjustments can be modified as per the manual, Good gains can be made from adding more timing and adjusting the AFR target to give best power. For more information see the manuals available in the help directory of ProECU
After that the fuel quantity and adjustments can be modified as per the manual, Good gains can be made from adding more timing and adjusting the AFR target to give best power. For more information see the manuals