However there is no value file for upgrades like the BAP - so we must do some data logging and build a new table ourselves. SCT helps with some fuel pump value files - for example if you replace a stock Marauder fuel pump with a GT40 pump, you can load a value file for the GT40 pump to bring your voltage table more in line with what the pump will need. The values in the table are actual voltage values passed to the fuel pump. The table is a function of Target Rail Pressure (vertical or y-axis) and Fuel Flow (horizontal or x-axis). In SCT's Advantage III, here is the stock Marauder fuel pump voltage table: All of these can affect the voltages required by the fuel pump at different flow levels! Changes to fuel hardware can be any of replacing the fuel filter, improving the fuel flow path, replacing a failed FPDM, changing or upgrading a fuel pump, or adding a BAP. So, as you change your fuel hardware, the base fuel pump voltage table in the tune should be adjusted to compensate, in order to minimize the required learning process. Every time the car is reprogrammed or the memory is lost, the ECU has an incorrect table to start with and the learning process can result in some very poor driveability (stuttering, shuddering, etc.) and in the worst case, can lead to lean fuel conditions and detonation. The problem is, if you change your fuel hardware at all, the voltage table in your tune will become more inaccurate. The result is that there is no negative impact on driveability due to the learning process if the car memory is lost (i.e., you disconnect a battery terminal). With factory hardware and a factory tune, the programmed base table is very close to the real values that are needed, and very little learning is needed. From this base table, the ECU will adapt ("learn") the voltage values that are actually required to reach specific flow rates. The Marauder ECU has a voltage table with the voltages required by the fuel pump(s) to maintain a desired fuel flow rate. Stock tunes carry values that are built to work across a large number of vehicles but you can greatly improve driveability by focusing table ranges on only what your car will actually encounter (a very basic example is if a tune contains data for running at 7000 RPM but you've set your rev limiter to 6000 - you do not need the 7000K data).
Here I will also discuss changing XNorm and YNorm (table axis) values in Advantage III, which is an important step for building a tune specific to one vehicle. I had discussed this a bit previously in my LiveLink thread here, but I need to start a dedicated thread to give this subject the detail it deserves.
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