Subaru Differential Fuel Pressure Compensation Guide
Version 1.0
1/18/2016
| Anchor | ||||
|---|---|---|---|---|
|
...
- Determine if compensation is to be used in ACTIVE mode (logging and compensation both enabled) or PASSIVE mode (logging only enabled).
- Set Fuel Pressure Compensation mode. This is determined by the "Fuel Pressure Differential Feature" table.
- If ACTIVE mode is chosen, set "Fuel Pressure Differential Compensation Activation" thresholds. The default values allow for using the compensation under moderate RPM and boost (above 2500 RPM and above 0.0psi of Boost). The compensation can be made active under all conditions by setting both of these values to their maximum negative values (0 RPM and -15.0 psi).
- If ACTIVE mode is chosen, set current mechanical base (differential) fuel pressure target within "Fuel Pressure Differential Target" table. By default the software is set to 43.5psi (3 bar), as is the OEM vehicle. If an alternate base pressure is being used, update the value within the software as necessary.
- Configure Fuel Pressure Sensor. Choose the input via "Fuel Pressure Sensor Activation/Selection" table, input the calibration via the "Fuel Pressure Sensor Calibration" table, and choose and input valid DTC voltage thresholds for the fuel pressure hardware in use via the "Fuel Pressure DTC Limit (Voltage)(High)/(Low)" tables.
- It is advisable to set the DTC thresholds a few tenths of a volt beyond the end of the valid calibration range and the end of the voltage range; for example, if the sensor uses 0.5v-4.5v for its sane range, setting the DTC limits to 0.25v and 4.75v should yield good results. A "C0BB3" DTC will be set for a Fuel Pressure Sensor Low Voltage error and "C0BB4" DTC for a Fuel Pressure Sensor High Voltage error. You may choose to adjust the Deadband Range, Sampling Rate and Smoothing Factor but the default values should work well for most sensors.
- Depending on the analog input chosen, you may need to remove DTC's for the OEM hardware to prevent the CEL from illuminating.
- If the C0BB3 or C0BB4 code is set, the Differential Fuel Pressure compensation is defaulted to zero (inactive). This functionality can be tested by quickly removing the fuel pressure sensor connector while the vehicle is running.
- It is advisable to set the DTC thresholds a few tenths of a volt beyond the end of the valid calibration range and the end of the voltage range; for example, if the sensor uses 0.5v-4.5v for its sane range, setting the DTC limits to 0.25v and 4.75v should yield good results. A "C0BB3" DTC will be set for a Fuel Pressure Sensor Low Voltage error and "C0BB4" DTC for a Fuel Pressure Sensor High Voltage error. You may choose to adjust the Deadband Range, Sampling Rate and Smoothing Factor but the default values should work well for most sensors.
- Please see "TGV Duplication Mode" section in the Subaru Custom Sensor Logging document if planning to utilize Custom Sensor Input option(s) while retaining TGV hardware.
- Sanity check the compensation's functionality by logging "Fuel Pressure Differential Actual" and if ACTIVE, "Fuel Pressure Differential Comp", which is the final active compensation based on fuel pressure. You can monitor "Fuel Injector Scale (Final)FINAL" to view the active changes being applied based on the fuel pressure compensation.
- WARNING! If the Fuel Pressure sensor hardware or associated wiring enters a failure state, it is possible to introduce either a direct short to the ECU's 5v power circuit or an overvoltage input to the ECU's 5v analog inputs. Either of these scenarios can potentially cause erroneous operation or ECU hardware damage.
...