13 mpg
 

07 5.9 cummins bought the truck 4 months ago it had 1 injector
Bad in it so I replaced all of them with a set of 60h II ever sense I've
Got 11 to 13 mpg but it could have been like that Before I Bought it
Air and fuel Filter have been Replaced lift pump volume good no
boost leaks but had to Replace The wastegate actuator
Injector return flow is good 90 ml the egt and the boost are high
Cuzin 70 On flat ground I think 12 and 825
Does anybody else have a clue or something else I can check

You need a tuner! look at the smarty!

That would be your problem. Maybe you can tune it better but not a good chance.

Boost and EGT that high indicates too much fuel, wihtout a tuner to modify the fueling curve it is what it is.

But I bought the truck from a buddy of mine and before the injector problem it was making 16 to 19 miles per gallon depending on his foot

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And the guys that II said that these injectors should give me better fuel mileage and power guaranteed

Guess that didn't work out to well for better mileage, eh?

You cahnged the injectors but the truck doesn't know that. You have more power now but not efficiency, that takes tuning.

What transmisison do you have? That will effect the end mpg big time.

Adding larger injectors and no other changes has not proven to add efficiency. The timing is late and inefficient so a lot of the extra fuel is just wasted. All it does is raise the boost and EGT's not the efficiency.

6 Speed 5600 If you think the programmer will help what programmer would you recommend smarty or efi Live

Is it an NV5600 that has been transplanted? That truck should have the G56 and it is ratio challenged. If you are goin any thing other than rolling down the hiway, 13 might not be far off unless it is at 55-60 mph.

EFI live is more robust but unless oyu understand how to write tunes you will have to buy them. Smarty is easier to use and has pre-built levels with parameters that are easy to set. The UDC version allows you to build tunes also.

A good tuner will help, but, not sure it will be enough to offset the larger injectors.

G5600

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I don't Think turning is my Problem
I Installed one stock Injector just to
See if it ran good Before I replace all six
it ran fine but it to Got 11 mpg

is the mileage hand-calculated or off the overhead lie-o-meter?

i'm running a smarty and quite satisfied, but i've been told by some that EFI Live is the equivalent of the second coming for our trucks...

if you're bone-stock and getting such poor mileage, your wastegate might've even gotten stuck open- if you're not building boost, you're leaving a lot of power (and thus efficiency) on the table.
the early G56 (pre-2007.5) has a 0.79 overdrive ratio, whereas the later G56 is a 0.74. also, other factors affecting your mileage could be gearing (4.10s will suck a lot more fuel than 3.73s), low tire pressure (reduced pressure = reduced diameter = effectively lower gearing), and whether you're 4wd or not (obviously, more mechanical drag from the xfer case and live front axle). there are tales of folks using ford-style front hubs and picking up a couple MPG.

truck details will help.

also, slowing it down a bit helps a LOT: i've noticed a 2 mpg (hand-calculated) difference between 68 and 73 mph. the motor's happy place is 1800-2100 rpm, so the further you get outside that in either direction, the worse the efficiency gets and thus mileage.

The Mileage is hand calculator I
change the wastegate Actuator because it was busted
The truck is four-wheel-drive and have 3.73