2018-2020 Mustang GT fueling limits

[mangosmoothie]

They might all be right. But first you have to understand how the gen3 lift pump is controlled. It has a fuel pressure sensor and the pump is on a pwm pid feedback control loop. Furthermore, since the pcm knows the actual fuel pressure, it modifies injector pulsewidth to compensate when the pressure drops.

So, if pressure drops, the pcm increases the pwm pulsewidth up to 100%. If at 100% duty cycle the commanded fuel pressure of 73 psi can’t be maintained, the pressure falls and the injector pulsewidth is extended. Keep in mind that on the stock car, port injectors only supply about 10% of the fuel at wot, so the pulsewidth has a long way to be extended before it hits a limit. The gdi pump, which usually does most of the heavy lifting, doesn’t need a ton of inlet pressure to keep doing its thing. Then there’s the throttle failsafe. I haven’t confirmed this on the gen3, but the ecoboost will close the throttle if it even thinks it doesn’t have enough fuel flow to maintain target a/f. It doesn’t even wait for the lean o2 signal to cut throttle. The programming appears to be there for that purpose.

So a conservative tuner might say that at wot your pump dc shouldn’t be over 90%, to account for possible plugging of the fuel filter or extreme weather conditions. Another might be fine with 100% as long as pressure doesn’t fall below x psi. Another might be fine as long as the port injectors don’t go above 90% duty cycle when the pressure falls. As long as the throttle cut is still active they’re all safe, but some are safer than others.

This is the best explanation of the fuel logic of the 2018+ I've seen.

First thing I'm doing is adding PI rail pressure and PI IDC (or whatever those PIDS are called) to the Ucal for 2/6 gauges (hopefully it lets me pick those). If I can watch both of those parameters live then I'll feel much better about this.

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[engineermike]

I don’t know how the ucal works, but in vcmscanner you can log lift pump duty cycle, lift pump pressure, port injectors pulsewidth (ms), and maximum port injectors pulsewidth (ms). That’s just the low pressure side, and the high pressure side has probably twice that many.

 

[illtal]

Wow that's ballsy for a shop to state and stand behind. I'd love to see how hard those injectors are working at wot.

the Edelbrock 2650 'Stage 1 uses stock injectors/no bap it's well over 600 WHP its not hard to believe.

 

[Zrussian13]

the Edelbrock 2650 'Stage 1 uses stock injectors/no bap it's well over 600 WHP its not hard to believe.

It claims up to 623 hp. Show me your dyno making that on stock injectors and then let me know well your set up holds up over time. No one said it can't be done. I said it's not smart.

 

[illtal]

It claims up to 623 hp. Show me your dyno making that on stock injectors and then let me know well your set up holds up over time. No one said it can't be done. I said it's not smart.

I had it done a long time ago without sheets and it made 617 in FL in the summertime. Installer ran it stock before I added DW95 and LTHs. So no sheets. pretty sure EB aint giving a warranty and killing your engine on purpose.

 

[mangosmoothie]

I don’t know how the ucal works, but in vcmscanner you can log lift pump duty cycle, lift pump pressure, port injectors pulsewidth (ms), and maximum port injectors pulsewidth (ms). That’s just the low pressure side, and the high pressure side has probably twice that many.

Is there a pulsewidth that = 100 IDC? and why have maximum port pulsewidth and port pulsewidth? One just records the maximum?

And is there a low side rail pressure or is lift pump pressure the same thing?

 

[engineermike]

Is there a pulsewidth that = 100 IDC? and why have maximum port pulsewidth and port pulsewidth? One just records the maximum?

I believe the maximum pulsewidth is the time it takes for one cycle at that rpm, so at 7500 rpm it would be 2/7500x60x1000= 16 ms at 100% dc. If the pulsewidth is 8 ms then the idc would be 50%.

And is there a low side rail pressure or is lift pump pressure the same thing?

I believe that’s the same thing.

 

[Jackson1320]

I seen your fuel system upgrade using the walbro pumps. I’m curious as to how the fuel gets from the passenger side tank when you deleted the Venturi style pumps?

The Venturi is not for pulling fuel from one side to the other. The Venturi just keeps the pump submerged in fuel. To move fuel from one side to the other. If we The fuel pump pulling fuel in starts a siphon and then gravity does the rest

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