What would make an 08' 6.4 get poor milage even after deletes?

J

JaMan

Local Hero
Weare on our way to SDX in a buddies 6.4 and it is getting poor milage 13.4 highway milage at constant 70mph, what could be the reason for such poor milage? H&S with a S&B intake 4" exhaust and egr blockoffs. Truck runs good but we cannot squeze any milage out of it. Any suggestions? New tires at 65psi good maintanence.

Thanks Jared
 
I was just wondering what problems people have had that resulted in poor milage that we could check, the truck has 100k on it and it may have something wrong. I have no trouble shooting experience on the 6.4's beyond the basics like boost leaks, low fuel pressure, areodynamic drag, poor fuel, or poor maintanence. I personally have put tuning, exhaust and intakes on 6.4s that get 17 to 18mpg.

Jared
 
dirty air filter?

i have yet to see anywhere close to 25 mpg's out of mine. more like 16-18 at 75 with 3:73's ... and 20 or so with 3:55's .
 
I should have qualified that,, I use an imperial gallon.. not sure how that relates to a US gallon. On my display it has shown 7l per 100km, but we all know that lies a bit
 
Mine got 11-12 city and 15-16 highway. At best. 3.73's leveled with 35x12.5 mud grapplers.

Is the truck smoking extra at idle or while cruising?
 
JaMan said:
No very clean running.
Click to expand...

Dirver error? Unless yall have that thing loaded down with crap that is causing extra drag or are hot rodding, I dont think there is anything simple you can check other then the obvious(filters and such). He might have one of those trucks that just is different then the rest. Or he may have an internal problem.
 
Auto hubs not unlocking - vacuum problem. Check your compression and fuel trims. These can have Inj probe or weak cyl and you might not notice it at first.
 
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