How Do I factor a Change in Fuel Rail Pressure?
05-07-2014, 10:56 AM
#1
How Do I factor a Change in Fuel Rail Pressure? I'm using HPTuners for the tune.
I recently installed a racetronix fuel pump (along with new injectors). From the reading I've done, it appears that the system assumes 58 psi fuel rail pressure all the time.
My new injector data (specifically the injector flow rate vs pressure delta (effective pressure) appears to match this as it shows a delta pressure of 58 psi at 0 Mpa (manifold absolute pressure). If my fuel rail pressure changes, how do I account for this? I haven't fired up the car yet because I'm still not finished putting the motor back in, but I'm assuming the rail pressure is going to change. Could I add the difference across the table and extrapolate the data?
For example if the fuel rail pressure is 60 psi at static, add 2 psi (difference from 58 to 60 at static) to each column across the board.
The relationship of flow rate vs effective pressure is linear, so off the top of my head I don't see an issue with this. However, I want to be sure I'm not missing something. These injectors are 78lbs @ 3Bar, so skewing the data will cause significant fueling changes.
If I'm going about this the completely wrong way, feel free to point me in the right direction.
I recently installed a racetronix fuel pump (along with new injectors). From the reading I've done, it appears that the system assumes 58 psi fuel rail pressure all the time.
My new injector data (specifically the injector flow rate vs pressure delta (effective pressure) appears to match this as it shows a delta pressure of 58 psi at 0 Mpa (manifold absolute pressure). If my fuel rail pressure changes, how do I account for this? I haven't fired up the car yet because I'm still not finished putting the motor back in, but I'm assuming the rail pressure is going to change. Could I add the difference across the table and extrapolate the data?
For example if the fuel rail pressure is 60 psi at static, add 2 psi (difference from 58 to 60 at static) to each column across the board.
The relationship of flow rate vs effective pressure is linear, so off the top of my head I don't see an issue with this. However, I want to be sure I'm not missing something. These injectors are 78lbs @ 3Bar, so skewing the data will cause significant fueling changes.
If I'm going about this the completely wrong way, feel free to point me in the right direction.
05-07-2014, 11:23 AM
#2
If you only changed fuel pump and injectors your fuel pressure shouldn't change I don't think.
As far as tuning you would need to get injector data and convert it to gm format unless it's already gm format.
Then need to input the injector data in your tune. After that probably fine tuning the injector data and/or ve table till your fuel trims are in check.
As far as tuning you would need to get injector data and convert it to gm format unless it's already gm format.
Then need to input the injector data in your tune. After that probably fine tuning the injector data and/or ve table till your fuel trims are in check.
05-07-2014, 12:59 PM
#4
I've got all the the GM tuning data from the injector manufacturer. They supplied everything (even the pulsewidth and pulse adder table data). However, I believe their pressure differential data assumes a 58 psi rail pressure(I could be wrong on this).
From what I've read, others have seen a change in fuel rail pressure when going to a different pump.
From what I've read, others have seen a change in fuel rail pressure when going to a different pump.