L92 Injector Duty Cycle over 100% with new intake (minimal mods)

[markislive]

I called the dealer for a price on a fuel filter, I was going to change for good measure. Come to find out I don't have an inline fuel filter like the older trucks. They said the fuel filter is now built into the fuel pump....Screw that

[midevil1]

I called the dealer for a price on a fuel filter, I was going to change for good measure. Come to find out I don't have an inline fuel filter like the older trucks. They said the fuel filter is now built into the fuel pump....Screw that

Yep, All one unit in the tank. $$$$$$$$$$$$$$$$$$$$$$$

[markislive]

60 psi and 100% duty cycle on the fuel pump has me down to 85% duty cycle on the injectors. I'm going to roll with that until my headers are installed. Thanks for the help midevil1.

How much can I increase the fuel pressure down the road? Is it safe to run above 60psi?

[murphinator]

Takes almost 3 times the amount of E85 to gasoline.

its not that much , more like 30-32% e85 stoich is 9.87

[midevil1]

its not that much , more like 30-32% e85 stoich is 9.87

Yeah after looking at my wideband charts. I was thinking about what the diff was in my 502. On c16 and then when I run E85 is rediculous. And the carb is twice as much to setup.

[Braemerz28]

I wonder if everything is really working the way it's supposed to? Take a look at the top tune...This is from my buddies 2009 6.2L Sierra 4x4 with Flex Fuel. Look how much bigger his injectors are. He is running 60% injector duty cycle with no mods other than a tune. His injectors appear to flow around 80% more than mine when comparing the tables.

Hi There,
I have a 2008 Siera Denali and just found the same issue. Stock it was set at 53.7 psi for High Flow and 43.5 at low flow. When I logged data, I was hitting 101% injectory duty cycle at the top of first and second gears. Stock rev limiter with only mods being a K&N filter in the stock box with an AirAid tube, and a Corsa cat-back.

I upped the high flow pressure to 58.0 which is the number also listed for Cold Engine and Default. On the next run this dropped the max duty cycle down to 94% right before the 1-2 shift at 5730 rpm. So, it' sbetter, but there's not much room.

I then went to the fuel pump table and allowed for 100% duty cycle anywhere above 4000 rpm and 159 lbs/hr. Ran again but this didn't seem to help at all. Still running 94-ish duty cycle.

A couple questions...
When I do a cold start I was reading 61.6 PSI during idle. But, nowhere in HPT can I fnd that number commanded.
1. Does anyone know where that commanded number comes from?
2. If it's "OK" to run that PSI during start up, would it then be reasonable to set the High Flow target to that number also to help lower the duty cycle?
3. What has been the experience of running this extra pressure? Since the low flow number is used for most driving, this hihger PSI isn't seen for that many hour relevant to the whole life of the truck.
4. There has to be some physical limit to calling for more PSI... any idea what it is? Or can you just jack these things sky high? (which doesn't seem right).

I'll keep playing with this and checking back here. Maybe we can learn something together.

Thx,
Scott