making it short

no chips on the rig, i live at 8700 ft elevation
magnaflow muffler, ats ehaust manifold, CAI, ats boost elbow are the only mods,

3.73 gears, '05, 3500 crew cab dually, 5.9, 156K on the odo, auto

truck is only seeing about 6000 miles per year at this time mostly long trips or towing 5th wheel, 10,000 lbs

november 2010, installed the boost elbow, truck began starting rough (real rough, lots of smoke etc.) and gas mileage dropped from 17-18 (empty) to 14, had complete BG service done complete motor flush, with no change ran ok when warm

mechanic said it needs injectors, had the entire truck gone through and it was determined that it needed a computer reflash, there was a service bulletin that fit my engine codes etc,

flash was done, truck runs great, gas mileage still sucks

what changed? any ideas?

 

Winter fuel? Or could still be injectors.

 

Welcome the EPA and low sulfer fuel and or winter blends with kerosene which has less btu's.
"november 2010, installed the boost elbow, truck began starting rough (real rough, lots of smoke etc.) and gas mileage dropped from 17-18 (empty) to 14, had complete BG service done complete motor flush, with no change ran ok when warm"
Try removing boos elbow,check for boost leaks .JMO

 

thanks, no leaks at boost elbow, after reflash truck run like new except for mileage,

it is not the winter mix, truck runs same crappy mileage all year now,

possible the new airflow is just calling for more fuel?