2005 poor milage

MoPower05

MoPower05

New member
Joined
May 24, 2007
Messages
620
This truck has never got good milage just wonder whats so different. It is used as my tow truck. Poor milage when I bought it in 2008, then it blew up 3 months later. Build new motor used DDP 50hp nozzles, 4" exhaust all stock cummins parts, and arp studs(stock turbo). 4.10 gears. Empty best I can do is 13mph. Pulling 32' gooseneck with pull truck at 8000lbs can only get 200 miles out of a tank of full(5.8mpg). At 70-75 mph runs constant 30-35 pounds of boost with no electronics.

33' all terrain tires
new converter single disk
dually
2" leveling front air bags rear
50 hp ddp nozzles
4.10 gears
gen 2 header
4" exhaust
stock turbo
 
You need to get gauges on it and watch what it is doing. Rail pressure is one.
Do you know what the drive pressure is with the stock turbo? 2 to 1!!!!
35 boost is putting 70+ psi in the exhaust manifold, restricting breathing.

Did you recaibrate the speedo for those tires?
 
the gears arent helping you at all. Also, good highway tires would be better than AT tires IMO.
 
fox said:
You need to get gauges on it and watch what it is doing. Rail pressure is one.
Do you know what the drive pressure is with the stock turbo? 2 to 1!!!!
35 boost is putting 70+ psi in the exhaust manifold, restricting breathing.

Did you recaibrate the speedo for those tires?
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Dont know drive pressure on this truck. tires are 31" tall same as a stock tire and speedo is dead on. Not sure why boost is so high had more than one guage and all have been the same. goes to about 41lbs with any incline at all with trailer in tow.

Yes a good tire would help, but for now its what I have.
 
What rpms as you turning at 70? 2350???

Get some 3:73's!
 
Yes the gears are not helping, but they are not the reason for the poor mileage.
I'll give my $.02 even though you probably have other problems causing the poor mileage.. In my 05, I noticed a definite mileage gain when I started running a 90hp smarty tune. Around town, stop and go, conservative and non conservative free way driving, I can usually get mid 17's, 18 if I'm easier on the petal. I even hit 20.1 mpg on a 300 mile stretch of interstate doing 65 with no AC (empty that is).

I'm not saying a smarty is the fix to your problem, but it may make it better.
 
You say you have a 2nd gen manifold? By any chance do you have the waste gate permanently shut?! Also, get you a tuner such as a smarty. It'll help you control those 50hp nozzles. It's not a good idea to run 'other than stock' nozzles on stock tuning.

BTW, it's a manifold not a header.
 
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My 05 qclb dually 4x4 six speed manual and 4:10 gears avarages me 14-15mpg everyday driving. Pulling my 26ft bumper pull camper (weighs about 7500) loaded for vacation was 11-13mpg. Pulling the dual tandem gooseneck with the pulling truck and people and all gear grossing in the 26-27000 range get 8-10 mpg.

I don't think that's all that good but it will tow anything I want at 80mph. Truck is all stock except a 4" AFE turbo back exhaust. I am interested in trying a smarty jr on it but I don't want to start the slippery slope of a tuner, then air dog, then a clutch and so on. I like it driving stock. I thought about bigger wheels but I don't like semi wheels so I was interested in the 19.5 setups. I have been told just the smarty will make a big diffference but I don't know. Subscribing.
 
jordanjames81 said:
one the gears,
second concern is the boost being so high.
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I have a set of 3.73s in the garage I will put them in just thought mileage is much worst than it sould be even with 4.10s. I have had electronics on the truck and ran 7 different tunes empty and pulling trailer, never made a difference. Truck just used to trailer pull truck, and it cost $700.00 to drive 1000 miles.

Boost why so high? no clue.
photo-68.jpg

photo-89.jpg
 
Curious about the header, not for sure why, just that is one of the things you don't really see on a daily driver, and maybe it is causing some of the issue?
 
ILLINOISRAM said:
I have been told just the smarty will make a big diffference but I don't know. Subscribing.
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^^You have been told correct. Like others have said, it's a sin to drive these trucks on stock tuning.

OP, I too am curious about the header. Why the need for it on a stock-ish truck?
 
zstroken said:
Curious about the header, not for sure why, just that is one of the things you don't really see on a daily driver, and maybe it is causing some of the issue?
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Never thought that caused the problem? Put it on when I built the motor because I had it from my pull truck. Its a t-3.
 
MoPower05 said:
Never thought that caused the problem? Put it on when I built the motor because I had it from my pull truck. Its a t-3.
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Yea, don't know either, just trying to think of things that might be an issue, and you just don't see those on anything that folks track the mileage on.
 
Had it on my pull truck in 2006-7 when I still drove and believe it got good mileage. Can't be 100% though.
 
It's not the gears. Probably don't help but isn't the reason for that poor of mileage while towing. I have never seen mine get less then 8 mpg and I have 4.10 too.
 
smalley said:
It's not the gears. Probably don't help but isn't the reason for that poor of mileage while towing. I have never seen mine get less then 8 mpg and I have 4.10 too.
Click to expand...

It plays a big part of it.
 
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