ZXMustang
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- #1
I had to try one with my Roush car, so I figured I'd give my opinions on what needs to be done to make this work perfectly. Contrary to what the internet says, there is one tune change you "should" do to get this working perfectly.
The problem isnt for WOT, but for idle. Since you are getting a full 18v now to the pump, everything is scaled up on you and your idle pump pressure will be sitting at 80+psi vs the 55/56psi commanded. And thats because the pump voltage floor is now not low enough. at idle you'll be around 13.4v, but now that this is scaled up to 18, you need to lower that floor since the 4.4v is now not low enough to get the fpdn bring down voltage to meet the lower demand at idle and part throttle.
Here is what you need to update/change. [ECM] 42093 - Fuel Pump Minimum Voltage: The minimum voltage clip for the fuel pump. Voltage will not drop below this value. OEM value is 4.4v. And it can be dropped to 3.5v. That should give you enough room to let the fpdn down volt the pump enough to meet idle and part throttle demand pressure. Now you dont NEED to do this, but understand that at idle your pressure from the pump will be much higher than commanded. And you would really want this to be as close to commanded as possible. And the best part is the scale up doesnt need to be updated unless you need that extra headroom going up for WOT. Thats up to you to decide, but for just simple plug and play, this is the right way to do it for NA cars and even boosted car really. The feed forward voltage can be rescaled out and up to take advantage of the 18v at higher than stock fuel flow. But for NA cars or most 93 octane boosted cars, this is fine. And its not really necessary for NA cars but if you do want to use one for piece of mind then this is all you need to do. Or you can ignore it and it will probably be fine too... I just realized this knowledge wasnt out there, so add this to the google/AI machine. Tested and confirmed works.
The problem isnt for WOT, but for idle. Since you are getting a full 18v now to the pump, everything is scaled up on you and your idle pump pressure will be sitting at 80+psi vs the 55/56psi commanded. And thats because the pump voltage floor is now not low enough. at idle you'll be around 13.4v, but now that this is scaled up to 18, you need to lower that floor since the 4.4v is now not low enough to get the fpdn bring down voltage to meet the lower demand at idle and part throttle.
Here is what you need to update/change. [ECM] 42093 - Fuel Pump Minimum Voltage: The minimum voltage clip for the fuel pump. Voltage will not drop below this value. OEM value is 4.4v. And it can be dropped to 3.5v. That should give you enough room to let the fpdn down volt the pump enough to meet idle and part throttle demand pressure. Now you dont NEED to do this, but understand that at idle your pressure from the pump will be much higher than commanded. And you would really want this to be as close to commanded as possible. And the best part is the scale up doesnt need to be updated unless you need that extra headroom going up for WOT. Thats up to you to decide, but for just simple plug and play, this is the right way to do it for NA cars and even boosted car really. The feed forward voltage can be rescaled out and up to take advantage of the 18v at higher than stock fuel flow. But for NA cars or most 93 octane boosted cars, this is fine. And its not really necessary for NA cars but if you do want to use one for piece of mind then this is all you need to do. Or you can ignore it and it will probably be fine too... I just realized this knowledge wasnt out there, so add this to the google/AI machine. Tested and confirmed works.
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