2016 Charger ProCharger dropping fuel pressure, but strange Inj PW & DC too

[S-351R]

ProCharged 6.4, 8psi SC kit, supplied 56# injectors, first 400lph pump then new Hellcat pump with visual confirmation that no t-fitting pressure leaks in-tank.

It maintains 58psi FP and idle and cruise, but still falls eventually to ~44psi during WOT pull. WB confirms leaning out at WOT despite big changes to VE (non-ANN)

1. Pls help me brainstorm where to chase the FP drop issue...

2. Why is the Inj PW flatlining at 18ms as early as 4700 rpms at WOT while Inj Duty Cycle is still climbing in the 70s-90ish? Even though FP is dropping, this seems like a mismatch in Injector value readings. And, since there is no datalogging of FP or Pump DC, does the PCM even know FP is dropping?

3. Even at the lower 44psi FP, the injectors should still support the 630rwhp she did make on the dyno without going so lean so early, correct? Malfunctioning injector?

WOT log and file attached. Any thoughts appreciated.

[LilSick]

1. Pls help me brainstorm where to chase the FP drop issue...

Lack of a return.

Both systems are dead headed but HC has a computer controlling voltage to the pump ramping it in when there is boost. Yours does not. Personally i prefer steady voltage to the pump and a return system with the regulator just past the injector

[LilSick]

2.a) Why is the Inj PW flatlining at 18ms as early as 4700 rpms at WOT while Inj Duty Cycle is still climbing in the 70s-90ish?
2.b) Even though FP is dropping, this seems like a mismatch in Injector value readings.
2.c) And, since there is no datalogging of FP or Pump DC, does the PCM even know FP is dropping?

3.a) Even at the lower 44psi FP, the injectors should still support the 630rwhp she did make on the dyno without going so lean so early, correct?
b) Malfunctioning injector?

WOT log and file attached.

3c) Any thoughts appreciated.

2.a)You have 'inj pw avg' at the bottom of a looong list of parameters. What is polling interval?
2b) ^^^
2c) Nope, but our scats have a table to account for it [34080]

3.a) You have a cyl 8 misfire on that pull. That log is a 6th gear dyno pull yeah? Did you look into the misfire?
b) ^^^

3c) I think it would be happier with a better fuel system, better fuel, and more than 10 deg of timing

[S-351R]

Yes, definitely prefer return style systems...

LilSick-
2a. Polling is Fastest at 0 ms, and my Chart was showing it to be very responsive and climb as expected, except that it just maxed out too early. I do not think it was just low-fidelity lines. Here is my Layout 2016 Charger ProCharger Layout.Layout.xml

I will clean up the channels list, but given that I was consistently going lean above 4600, and VE made no change, I'm inclined to believe the 18ms max, and not sure why DC was still increasing.


2c. I think solving the physical fuel drop of roughly 14psi is first, but is it worth messing with this table as a bandaid to get more Pump DC (since the injectors should do better with right pressure)

3a. I did notice, may be real and related to the leanness, but did start accumulated before lean. It is also my understanding the the #8 Misfire is very common in the 2015+ models, is a strange phantom reading, and that increasing Net Positive Torque alleviates it (was Whipple's recommendation). Will definitely monitor closely. This was in 5th gear


Thx for the input!

[B00STJUNKY]

Yes, definitely prefer return style systems...

LilSick-
2a. Polling is Fastest at 0 ms, and my Chart was showing it to be very responsive and climb as expected, except that it just maxed out too early. I do not think it was just low-fidelity lines. Here is my Layout 2016 Charger ProCharger Layout.Layout.xml

I will clean up the channels list, but given that I was consistently going lean above 4600, and VE made no change, I'm inclined to believe the 18ms max, and not sure why DC was still increasing.


2c. I think solving the physical fuel drop of roughly 14psi is first, but is it worth messing with this table as a bandaid to get more Pump DC (since the injectors should do better with right pressure)

3a. I did notice, may be real and related to the leanness, but did start accumulated before lean. It is also my understanding the the #8 Misfire is very common in the 2015+ models, is a strange phantom reading, and that increasing Net Positive Torque alleviates it (was Whipple's recommendation). Will definitely monitor closely. This was in 5th gear


Thx for the input!

IDC and Inj PW are not synonymous. It's natural for IDC to increase as RPM increases, given a constant Inj PW.

IDC = Inj PW / Window of time available for injection event.

Window of time available for injection event is calculated by figuring out cycles per second for a given RPM, then taking the inverse of that number to determine seconds per cycle (which is your window of time available for the injection event).

A 4 stroke cycle means 2 revolutions of crankshaft rotation for a single injection event.

So, RPM / 60 (to reduce to Revs per second) / 2 = cycles per second.

1 / cycles per second = seconds per cycle (your window of time available for the injection event).

3000 RPM / 60 / 2 = 25 cycles per second.

1 / 25 = 0.04 seconds per cycle (or, 40ms). Also known as your window of time available for the injection event.

A 20ms Inj PW @ 3000 RPM would equate to 50% IDC (20 / 40 = 0.5, or 50%).

6000 RPM / 60 / 2 = 50 cycles per second.

1 / 50 = 0.02 seconds per cycle (or 20ms). Also known as your window of time available for the injection event.

A 20ms Inj PW @ 6000 RPM would equate to 100% IDC (20 / 20 = 1.0, or 100%).

Hope this helps clear up some of your confusion.

[S-351R]

Thanks for the detailed description, and think I got it...

So even as PW may become flat while RPMs and DC climb, it seems that 18ms is the max for the injectors.

Seemed to hit it pretty early where ProCharger says most of their tunes are only hitting 16ms (though this car is more modified), but this then is probably due all to the dropping fuel pressure for an injector already a bit stretched. And leaning out despite high VE changes suggests the same.

Well, back to chasing the pressure drop in hopes of delaying a bigger fuel system, especially when plenty of folks are making more power with these lines and pump.

[LilSick]

What he is saying is that 18ms is the max for any injector at 6650 rpm

There is a filter inside the regulator side (passenger side) 'pump' (i know its not really a pump but dont know what it is called). Maybe somehow that filter is restricting flow and creating your pressure loss???

[S-351R]

Well, new ID1050x's are in, and now have plenty of fuel, with a nice liner slope in Inj PW as RPMs climb. DC is now obviously much lower.

BUT, FP drop remains unchanged under WOT.
So, gonna just do full return style system and eliminate whatever issue it may have been given the time sponge that might have turned into.
Thx all!

[S-351R]

So who knows what the FP issue ultimately was, but with the return style system now, we hit 715rwhp nice and clean. Thx again for the input.