Fuel milage getting worse

BravoZulu81

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I have an 08 6.4 with about 190 on the clock, fully ******d GH tunes. When I first ******d just the *** my fuel milage rocketed up and it was awesome. I was getting 15-16 consistently. Once I ******d EGR and replaced my up pipes and down pipe unnoticed a weird drop.. wasn’t huge and I put a camper top and new tires on around the same time so I assumed that was the cause. However recently it seems to be dropping and getting worse and worse. Back to the 13 range. I’ll give that it is time for oil and fuel filters but can’t think that’s the issue. I seem to be building boost fine but power does seem a little off as well...

Any insights


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kleake

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Sounds like an issue but driving speed, head wind, etc can really effect it. I have GH, exhaust, manifolds, pipes, etc. Empty at 70mph I get 18-19mpg. Push it up to 75mph and it drops to 16ish, headwind and it will drop a little more. Pull almost anything and it's in the 12mpg range. 36ft camper with boat behind and its 9mpg but that's a 25k load. These trucks really like the highway with minimal drag, but it doesnt take much to cause a drop in mpg. I'm not sure how much your topper effects it.

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BravoZulu81

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I’m pretty well a granny and rarely get above 70mph as I notice it drop then too. Granted with my 37’s I don’t expect anything like what you are getting but I’ve always had them and just feels different I guess.

What tune do you run? I may reload mine to see if that helps too.

I’ve also tried a few different additives to see if they help. Usually it seems like they do for the first 1/4 tank then falls off again.


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kleake

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I'm running 35's so not much different. City driving also kills the mpg. If I drive around town I get in the low teens as well. My usual mix of 70% highway 30% city will put me at 14-15mpg average. I'm running GH with custom transmission settings. I run it in "street" mode most of the time on my mini maxx.

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BravoZulu81

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johnnyroastbeef

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so i had the same MPG symptoms as you described. I also noticed a lot more smoke on acceleration. so I did some looking online and saw a lot of other 6.4 owners describing similar stuff and attributing it to the EBP sensor.
I had my mechanic just replace it as it was cheap and no more smoke and better MPG.
that was a while back and i'm starting to see the smoke increase again. I read that many guys also replace the tube that the EBP sensor connects to. so i'm already thinking of replacing that tube too.
but to answer your question i'm kinda throwing parts at it. as i understand the tube and/or sensor gets clogged with soot and can't properly read back pressure and the computer adds more fuel as a correction? thus producing more smoke and making MPG worse. (maybe someone smarter can explain that better?)
But if you're not seeing any additional/excessive smoke when you hit the gas, maybe your issue is something else.
 
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sootie

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so i had the same MPG symptoms as you described. I also noticed a lot more smoke on acceleration. so I did some looking online and saw a lot of other 6.4 owners describing similar stuff and attributing it to the EBP sensor.
I had my mechanic just replace it as it was cheap and no more smoke and better MPG.
that was a while back and i'm starting to see the smoke increase again. I read that many guys also replace the tube that the EBP sensor connects to. so i'm already thinking of replacing that tube too.
but to answer your question i'm kinda throwing parts at it. as i understand the tube and/or sensor gets clogged with soot and can't properly read back pressure and the computer adds more fuel as a correction? thus producing more smoke and making MPG worse. (maybe someone smarter can explain that better?)
But if you're not seeing any additional/excessive smoke when you hit the gas, maybe your issue is something else.

No point replacing the tube unless it's plugged. You can achieve the same thing by poking a wire hanger thru it.

If the truck can't read ebp correctly, it has no idea where to place the veins of the high pressure turbo. Nothing to do with adding more fuel, it just doesn't push enough air to match the fuel it's being fed as the fail safe is to default open as opposed to closed to avoid blown head gaskets and the like
 

BravoZulu81

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No point replacing the tube unless it's plugged. You can achieve the same thing by poking a wire hanger thru it.



If the truck can't read ebp correctly, it has no idea where to place the veins of the high pressure turbo. Nothing to do with adding more fuel, it just doesn't push enough air to match the fuel it's being fed as the fail safe is to default open as opposed to closed to avoid blown head gaskets and the like



Makes sense. I haven’t noticed any excessive smoke though. However I drive like a dang grandpa usually so rarely would I ever have seen anything.

It’s weird some days I also swear the truck feels more responsive and has more power. Sorta all sounds like it could be tied to this.

Would anything on this have changed when the truck was ******d which could be causing the issue?


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