LLY: 04.5 Fuel Mileage Worse Than Others?

[04LB7yz]

I saw another thread on this and it got me thinking that i have issues with my current mileage. I have everything that is in my sig done to my truck.

The best mileage I can get unloaded is 15 mpg no matter how i drive it or what tune i am in. The truck is stock height with torsion keys removed with 265-70-17 tires...

My previous truck was an 04 LB7 with a 6 inch lift and 36X13.50X18's with an aggresive tread pattern. That truck would pull 23 mpg all day long no matter how i drove it with almost the same mods.

Anyone else with a similar setup have mileage numbers? Any insight is greatly appreciated! :thumb:

 

[countrycorey]

Hand calc'ed or is that what the DIC says?


Corey

 

[04LB7yz]

Hand calculated...

Truck runs and starts awesome, no fuel smell, very little smoke even on the big tune..

 

[04LB7yz]

It actually gets the same mileage that it got when i bought it about a year ago and it was virgin... completely stock. All mods have been done within last 15,000 miles truck currently has 150,000

 

[Chevy1925]

i just wanna know how you're driving around on no torsion keys!

how clogged up was the intake runners/y bridge from the egr?

 

[04LB7yz]

I wouldn't say it wasn't horrible but definitely not ideal i cleaned the elbow and as much sludge as i could out of it. And my bad haha bolts removed from torsion keys

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[melms23]

How is the serpentine belt and accessories? How fast do you drive?
When we had our 05 it was bone stock and the DIC had read as high as 23 on one trip to iowa.

Do you have heavy wheels and tires? I notice that really kills the mpg on my LMM.

On the other hand I don't know how guys get such good milage. My LMM gets a consistent 16.5-18 and it doesn't even weigh 7000lbs

 

[Awenta]

How about the basics. Fuel filter, air filter. Clean the maf. How are the injectors? Who's tunes

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[Awenta]

Also is that highway or city mileage? Because mostly city that wouldn't be too bad.

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[solidrunner]

My 2004.5 with the mods I have listed in my sig gets 21-22 on the freeway according to the dash display. Around town it's lucky to get mid teens.

 

[bmc1025]

Did you hand calc the LB7? Many tuners leave the DIC calculation tables alone in the tune and the DIC gets very optimistic.

 

[ALLY Fox]

Looks like you live in minneSOta, do you have long warmup times? Tires/tire pressure can have a big influence on fuel economy. Are you buying your fuel from the same place as your LB7 and are they pumping 1D or 2D? #1D is less efficient than #2D. I get about 16 local and 19-20 hwy calced consistently with B&W hitch installed, heavy H2 wheels and a moderately heavy foot.

 

[04LB7yz]

Fuel filters are both relatively new maybe 2k on them, air dog filter and the one on the engine.

The serpentine belt is also pretty new along with tensioner pulley and idler pulley. As i come to a stop though my lights and everything go dim for a second which i think is kind of weird.. It isn't very noticeable but if you pay attention you can see it.

The air filter gets cleaned once a month if not twice, so no problems there i don't believe.

The LB7 would read over 30 mpg on the DIC when i was actually getting 23... My LLY will read backwards it will say i am getting 12.5 when i am getting 14.

The fuel i buy usually comes from 1 of 3 stations that sell a lot of diesel. #2 is what gets put in the tank. I also have B&W turnover

If i drive below 60 mph i can average 16-17 but as soon as i drive over 60 say 70+ my mileage goes to sh$t in a hurry..

If I could pull 20 mpg out of this thing i would be amazed!

 

[04LB7yz]

The balance rates all check out good for the injectors. When i bought the truck it had a bad FPR and it had a pretty decent lope to it 2-300 rpm difference at idle. That was replaced within a week after i bought it and it cured the lope. But who knows how long it was like that. Is there something that could go wrong if that was left untreated for a long time?

 

[Awenta]

Take the belt off and spin the alternator. It could be going out and dragging really bad putting a bunch of unnecessary load on. Unless it's bad batteries putting alot of load on the alternator.

I don't think that's worth 5 mpg but it may give you 1.

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[04LB7yz]

Is there anyone out there who has experience with the bills custom intake vs say an S&B kit? The bills has a large S&B filter but i am curious as to proper placement of the MAF. It never threw a code and it was put it on before it was tuned..

The air filter gauge with a freshly clean air filter will also pull into the red after one good pull down the road. Is this normal? The tube is 4 inch i believe so i cant imagine there is any restriction to it...

 

[04LB7yz]

So I recently installed a fuel pressure gauge at my fuel filter block and saw that I was running around 9psi. Ive heard mixed ideas with lift pump pressure so i decided to turn it up. I set idle pressure at 20psi and at WOT it will drop to roughly 17psi. The truck seems to like it a lot, it is way more consistent when making a pull. While shifting it seems to recover much better after defuel, not that it was bad before. Anyways after putting roughly 250 miles on it running the higher lift pump pressure I've seen an incredible increase in fuel mileage. At 75mph I can now see 17mpg on the DIC where as before I would only see 12.5-13. I haven't gotten fuel yet so that's not hand calculated but the increase on the DIC blew my mind.. Has anyone else seen or heard of anything like this?

 

[Burn Down]

What kind of Gauge are you using? The gauge sounds off to me... 20psi should be making the FPR real angry. I would recheck your pressure with another gauge.

 

[04LB7yz]

Its an electronic Auto Meter cobalt, seems to work without issue... I'll put a mechanical gauge on the filter block and see what that says.

On the other hand, say the gauge is off and previously my pressure was at 5psi or something then increased it to 15 why would i see an increase in MPG's?

 

[04LB7yz]

It idles exactly as it did before so I cant imagine that the FPR is being thrown off