My mpg went up with the LT's!!?!! Around town with stop and go city traffic I get 13+ but on the highway I'll get better than 18.5mpg. It really depends on what spped I drive and how much of an *** i feel like being

 

The only reason all cars are set to 14.7 is for the tree huggers..at 14.7 is were you get least amount of hydrocarbons or whatever bullshit they say "Pollutes" the air..thats why on 2500 trucks with the 6.0 have the Power Enrichment Delay..which a WOT you run 14.7..a 6.0 burns alot of fuel at WOT which "Pollutes" the air more

15.5 is were you get your maximum fuel efficiency, read that on a tech article off EFI Live's site...

Look at the Aussi cars, they have a Lean Cruise mode set in the PCM..hopefully some one will chime in on what Air Fuel Ratio they actually run while in Lean Cruise Mode

 

so do you think a long road trip at 15.5 wont harm anything? The reason I am asking is because I wil be starting tuning hopefully next week and this is one of the thing I have read about and wondered.

 

20-21.5 before the cam. Looks to be about the same after the cam and re-tune...other mods in sig

 

honestly i dont think so..when my 5.3 blew up.. i had been running 15.5 for a long time..yes the plugs were white but the pistons had no pitting on them and looked just like a 125,000 mile piston....

 

i took many many trips to burkburnett, tx and back(bout 2 1/2 hours each way) with my last truck and it never missed a beat...i run tr6's and they looked just fine at each change, whatever that means to ya

 

Thanks for the replies!! So are you guys running the custom EFI operating system on your trucks?

 

i'm not on this one...i did on my 05

 

so it was just left in SD mode instead of loading the custom OS?

 

they don't have a custom os for mine yet. the way it was explained to me is you don't need unless you're doing some kind of FI...We just tuned it in open loop speed density