lb7 80+ injectors/bad mpg
 

i bought my truck couple of months ago, cold air, five inch straight exaust, banks auto tuner, 80+ horse injectors just put in, i have found the milage to be TERRIBLE, bought the truck thinking 20 mpg, bo im getting 13 with no trailer, will an efi live fix this somehow , i cant up the power because my fifth wont hold it, i have already dumped the banks so i can pull a trailer without incident. anyone have any ideas

You will need custom tuning (efi live/hp tuners) To take advantage of the larger injectors.

larger injectors need to have the timing pulled back some as they put more in more fuel in less time. This acts like an increase in timing and can push it past whats good for mileage or health of the motor. They may also need some other tweaks like fuel rail pressure and pulse width duration.

from everything that I know, it seams that most people have a drop In mpgs after putting in larger injectors and then get all or most of it back after getting it tuned for them.

so if i tune for timeing will it up my power to the point that fifth gear wont hold, whats a good transmission to get to hold the power, can my local tranny shop do the mods or do they have to machine case parts to beef it up- the whole thing seems like such a pain i wish the last guy had just put normal injectors in it

Custom tuning with efi live can restore the horse power to stock levels by lowering the pulse width of the injection event. This may or may not help with the transmission issue as once they slip it will tend to continue slipping until fixed.

I don't know if your local tranny shop can do this, ask them how familiar they are with Allison transmission and how often they work on them.

An upgraded transmission usually doesn't cost much more then rebuilding it back to stock. In my opinion you should get a suncoast 3 or better and efi live tuning for the injectors.

If you get a transmission that can hold more power then if you ever get the itch to turn up the hp the transmission can take it. You can also install the dsp switch for switching tunes on the fly. It may me more expensive then you would like but you will like your truck much more after.

thanks for the tips, i will look into it