Subaru Flex Fuel Tuning Guide
Subaru Flex Fuel Tuning Guide Subaru Flex Fuel Tuning Guide Version 1.1 10/9/2019 Flex Fuel Overview Additional Resources and Tools – Ethanol Ethanol Content and Stoichiometric Ratio Initial Flex Fuel Setup Determine Multiplier Value for High Ethanol Tables – Example Octane-Based FF Tables Ethanol Content Measurement and Analog Input Considerations Basic Outline to Enable and Tune for Flex Fuel DIT Flex Fuel Fuel System Considerations ECDS (Ethanol Content Delay System) Troubleshooting Flex Fuel Related Custom DTCs: Flex Fuel Overview "Flex Fuel" (FF) functionality is supported for select turbocharged Subarus utilizing the COBB Custom Features ECU. In short, COBB's Flex Fuel feature encompasses these custom code features: Allows for seamless switching of fuels between low ethanol fuel and high ethanol fuel. Utilizes analog ECU inputs for ethanol content via tuner selection between the existing TGV (Left), TGV (Right) and Rear O2 Sensor analog 0-5v inputs. All main tuning functions covered by Flex Fuel options: full and variable blending of AVCS, Boost Control, Injector Scaling, Open Loop Fueling, Ignition Timing, Cranking Enrichment, Warm-up Enrichment, Fuel Mileage Display Correction (non DIT), injection timing (DIT only), etc. OEM-level functionality and finish: adjustable ethanol content signal sampling rate, smoothing factor, deadband, DTC detection, etc. In general, there are two primary goals of a full function Flex Fuel implementation: 1. Account for changes to ethanol content (stoichiometric ratio). This allows for the ECU to account for the variable amount of fuel required to achieve a correct air fuel ratio as ethanol content changes. This is all based on a linear relationship and somewhat easy to calculate; scaling for these items generally requires a 1:1 relationship with the ethanol content delta.
[Show full text]