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Feb 29, 2020 | 03:48 PM

Dgthomas67

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5th Wheeling

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Problem

I have a 2008 F450 6.4 4wd. I had the EGR removed and deleted and the DPF and CAT. I have a SCT X4. I am running the Performance tune. I have the Performance, Tow, Street, Extreme and Stock with no problem (Which means only Delete with nothing else.) I did not see any Fuel Mileage changes. I am getting the same (Bad Mileage). Why is this?

Mar 1, 2020 | 06:50 AM

speakerfritz

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Bad mileage on a 6.4 is 10 mpg or less and usually indicates valve train wear.

if your getting 11 going up hill and 14 going down hill you are fine.

Mar 1, 2020 | 07:51 AM

Dgthomas67

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5th Wheeling

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Valve train wear

How hard and expensive is that to fix

Mar 1, 2020 | 07:57 AM

Dgthomas67

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5th Wheeling

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Valve train wear

Is there another test for the valve train? This truck runs great no loss of power. Clean oil. No smoke. Instant start.

Mar 1, 2020 | 11:47 AM

sxrfun

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From: Ontario , Canada

Didn't you just do this delete like 2-3 days ago? How far have you driven since? Are you going by what the lie o meter in the truck says for mileage?

Mar 1, 2020 | 11:56 AM

sxrfun

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From: Ontario , Canada

Also you have a f450.......what rear end do you have?

Mar 1, 2020 | 12:44 PM

Dgthomas67

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5th Wheeling

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Did delete date

I did the 2/28/2020. And like I said it has no noises and sounds great and runs awesome. And i am in the performance tune .

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Mar 3, 2020 | 08:10 AM

sxrfun

Elder User

Joined: Mar 2011

Posts: 661

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From: Ontario , Canada

Quote:

Originally Posted by Dgthomas67

Howndo I find out which rear end do I have. I am.new to diesels.

It'll say on the door sticker on the drivers side door jamb.......I think you'd most likely be looking at 4.88's or I think 4.30's may have been an option? Either way....engine revs high with those gear ratios and you won't get great mileage no matter what....f250 and f350 came with 3.73 or 3.55 gear ratios and got better mileage.