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Boost to high??

21K views 81 replies 17 participants last post by  joestroo 
#1 ·
I have an '08 F-350, had it about a year. It's got a banks cold air kit, dpf-r kit, diablopsort predator and extreme powerpuck. With all that you would think i could get some good mileage.....i wish, i get about 12mpg. I believe it to due to my turbo running to high at highway speeds. It will run, with the chip and tuner in, at about 20psi driving 65-79 miles per hour on a flat road. When the truck is stock it runs at 18psi going 65-70 miles. Anybody got any idea's what may be the cause, or what is everyone else's turbo's running at??? I had it at my Ford dealer about 2 weeks ago, they were no help, couldn't find a problem. Any help would be great!!!
 
#7 ·
i had a 08 f450 with 430 gears and running down the road at 70 i was pushing 25ish with a bully dog and pegging the guage with a load.but i dont know i went through 3 engines in 57000 miles 2 without mods and 1 with.
 
#6 ·
doubt it man the turbos are controlled by the tuning so some tunes may run high boost at low speeds others may run low, just depends. i would only be worried if you are running over 50 psi or you cant make more than 30 psi or so
 
#10 ·
thats waaay too much boost to be running when just cruising. you should be at 10 max on a flat road. do you have a lift of bigger tires? what are your EGTS while cruising? mine with the SCT will run 8 PSI or less cruising and if i slowly roll into it from about 60 mph it will hit 42 psi.
 
#12 ·
ya i only ran 10-14psi stock at 65-70 mph now with spartan 210 i run right around 8psi. Is the truck lifted and big tires i have a buddy with a 8" lift and 38's that runs down the highway at 20psi
 
#21 ·
Man, I like it a lot. The DD clutch cost me a pretty penny, but it's so nice. I can slip the clutch in 3rd and haul ass. The 250 tune with 37's got me a 1.888 60' starting in 2nd and a 14.54 @ 92.30 Fifth gear is my favorite, goes from 45 mph to 95 mph. :evil

I can't wait until the 310 gets released! :redspotdance: I'm hoping to get into the 13's.
 
#22 ·
Ok boy's, i put an Edge Race evolution in the truck, got my egr valve switch out, and i still think the boost is high. I was running empty driving 65-70mph, and the boost was at 15-16psi. With my 2 quads loaded up it runs at18-24psi, on flat road. Any other idea's what i can check?? I'm all out of them!!!!
 
#25 ·
But everyone else who i have spoke with, who runs the same tuner runs 7-11psi on a flat road. There must be some thing else wrong.......The boost ran high stock, and with both the tuners i have had in the truck.
 
#27 ·
do you have lift/tires or anything else that would create drag?
 
#26 ·
hard to say, have you checked the linkage running to the high pressure turbo? It should move freely when the key is off, other than that man its hard to say, timing, injection PW, VGT duty cycle have everything to do with boost, and are all controlled by tuning...
 
#33 ·
If you have a boost leak you'll probably never make good boost

Have you tried to move the actuator for the VGT turbo? if that is sutck in one position your boost will be low off the line and high on the top ect. try moving that by had with the key off if that seams to b e ok take it to the dealer and have it checked out.
 
#34 ·
Yes i have tried that, and it moves fine. I get lots of boost off the line to, it just seems to run high at highway speeds. I'm wondering if i can get my boost down if it will make my mileage better??
 
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