5.9 Scan Rail Pressure

[Silverbackoffroad]

What is an acceptable range in Actual VS Demanded rail pressure.
Truck feels good, sounds good and responds well on acceleration.
See enclosed scan.

[Jim P]

Think the service manual states +/- 300 or 500 psi

[Silverbackoffroad]

Any reason for the 2 peak gaps @ aprox 3/4 time in the scan? All parts tested to be functioning at spec.

[Jim P]

Can?t view the log off my phone so I have no idea what it looks like or any idea of what is done to the truck or anything to give any answer.

[Silverbackoffroad]

well if you have a chance, look at the scan....there is some good data there. If anyone has a compared scan off a 5.9...please post it.

[JaegerWrenching]

You have a mechanical issue, have you done injectors recently or had any work done on the truck?

[Silverbackoffroad]

Injectors were replaced about 30k miles ago. Has typical air intake box upgrade, NO manifold intake changes. Exhaust is 4" from turbo.
Runs on a modified HP tune (enclosed) and has an edge tuner for additional adjustment. Running at stock on the edge gives runs the ECM tune.

[Silverbackoffroad]

I forgot to mention as well...it has a Fass pump that is putting out 25psi (as seen from an inline and wired gauge). I have replaced the ball and spring 2x with a new one coming soon. Yes...i did confirm proper return flow to the tank. I had to cut and drill the ball just to reduce the psi from 35.
When inspecting the "ball" it was compressed and "oblong"

[Silverbackoffroad]

Notice the FCA Demand and Actual!
AT 87.% throttle the FCA is demanding 16.8%
YET provides 63.8%? TOO many mA correct?
Is this an:
- FCA problem
- ECM problem

If it is the ECM, what would need to be changed in the tune file?

[Silverbackoffroad]

Enclosed is a scan BEFORE re-torque of injector tubes. NOTICE THE DIFFERENCE
All else remains the same.

[JaegerWrenching]

You have two main issues, #1 your fuel pressure map is asking for a lot of pressure at a low RPM, remember the pump is engine driven so it needs a certain engine speed to be able to move that much volume to make more pressure. #2 Try setting the PW map back to stock or at least close to stock and same for fuel pressure but smoothed and see what it does. This will eliminate if it's tune related or not. My opinion is you're asking a lot of the pump at a low RPM/low fuel amount by increasing fuel pressure and the PW map and it just can't keep up. Your goal would be to start stock and add little by little until rail pressure can not be maintained consistently.

Edit: i had opened the wrong file lol. Your file you supplied is stock lol.