So.. I'm testing this whole fuel usage theory with my lift kit and 35's.. I have, I won't lie, few times I punch it.. But most time I drive normal..

The following three fuel reports are as go..

1st one is with Diesel Kleen and the Stock Air Intake..

Gallons Added - 27.282
Trip Meter - 289.6
Cost - $75.00
$ PG - 2.749
MPG - 10.62

2nd report is Quadzilla Air Intake and no Diesel Kleen.

Gallons Added - 27.554
Trip Meter - 371.4
Cost - $76.02
$ PG - 2.759
MPG - 13.48

3rd report is Stock Air Intake and Diesel Kleen.

Gallons Added - 26.919
Trip Meter - 308.6
Cost - $74.00
$ PG - 2.749
MPG - 11.46

The 4th report is still in progress.. It's with no Diesel Kleen and the Stock Air Intake. Right now I am at 62 miles and still a ways above the full mark.

Not sure what this oddity in fuel mileage is from. I do however know that the 2nd Report and this current 4th Report are from the same fueling station.. Possibly quality of fuel?

We also have the hot tune in, EGT disabled and no puking.. Last puking incident was last Sunday.. Yesterday I rode her hard as a horse.. She never puked..

 

Could be fuel quality, also TYPE of fuel...

The basic cut-line for "normal" #2 and "TX-LED" (i.e. CARB) diesel is basically I-35. East of I-35, CARB diesel; west of I-35, "normal". Not exact, mind you, but a good guesstimate.

CARB diesel is known for it's drop in fuel mileage, among other things. It's supposedly because the entire eastern 1/3 of the state is "non-compliant" on air quality.
The pumps aren't marked, so you may have to discuss this with the manager of the station(s) in question. The chances of the cashier knowing (or knowing the difference) is slim.

-blaine

 

Yes fuel quality makes a lot of difference in these engines. Example... at out school bus garage they got the cheapest #2 they could buy for years and the fleet average was 5.4 MPG. They went to B5 soydiesel and premium fuel mix and it went to 6.45 MPG. I went on a long trip with a bus and got 9MPG for the 250 miles. So yes fuel quality does make a difference.

 

Hmm.. Thanks for the info.. The station that has shown me these high mpg was a Valero on the east side of I35.. the other two were on the west side of I35.. All my fuel stations are Valero, only station I use.. Reason being I have a fleet fuel card with Valero (don't ask how I got it, just have good connections).. So I thats the only station I use..

I'm going to keep monitoring it..

 

Storm, no problem with Valero, they are a Texas company (San Antonio) and the largest refiner/marketer in the country. They have bought every Refinery the Majors said could not be run profitable and have done so. Diamond Shamrock, Valero, Ultimar stations are all under the Valero flagship. Fuel quality does play a big part in fuel mileage, however fuel from Valero stations would be the last thing I would be questioning. You could always have it analyzed for BTU content ect.

 

I guess its not the same for diesel as gas. I live in a small town and have multiple times seen the same truck stop at more than one station, I don't know if they were dumping diesel or gasoline.

What am I doing that's so different? I get mad when I drop into the 14mpg range for "around town"= back and forth to work on country roads about 10 miles each way and of course driving through each town (5 lights and 3 stop signs).

 

Oh yes.. I love Valero and that is reason I only buy their fuel.. They have the best diesel I have seen in Texas..

So far I'm pleased with the mileage.. Grant it she drops to the 10s, 11s but hell 13.4 is good on a 4.5" Lift, 35's and a Hot Tune put in.. I'm going to keep tweaking around here.. I think it may just be the flex in the fuel thats doing it.. It could be worse tho!

Overall I'm pleased with the MPG.. Just wondering if DK or Intakes were making differences.. Like I said, I got the stock intake in now.. Before that i was running iwth the Quadzilla Monster Air Intake..

 

Keep up the research! I use DK too, although I have no other mods and never noticed a change with or without DK...just insurance I guess.

I have another question about the larger tires: This is the first 4wd where I DIDN'T add a lift and bigger tires and I don't plan to (won't fit in the garage), but every truck and jeep (1) I got the same or better milage...BUT the speedo's weren't re-calibrated, but with a large tire your actually going faster than your speedo reads right?...so that would mean you actually traveled farther then the odometer said?...or am I wrong?

 

Depends.. I have an SCT Livewire that lets me adjust my speedo.. so my speedo is pretty close along with my trip meter/odometer.. Tested it with a friends GPS... At 70 im doing about 68.. Even factory they are few miles under the actual speed the speedometer says.

 

I didn't know the livewire adjusted the speedometer. I know that with SCT tuning you have to enter the tire diameter for correct shifting, etc. but it doesn't correct the speedo. I think there are only one or two devices in the A/M that will do that and of course you can have it done at the dealership for certain tire sizes.

 

Sure does.. There's an option in it for me to adjust the tire revs/mile which adjusts the speedometer and odometer..

 

There's also some debate as to whether or not the difference in the "low sulfur" or "ultra-low sulfur" fuels effects performance and mileage. EPA says little to no change, but I trust that about as far as I can throw my truck. The Freightliner, that is. There's been some issue lately on pump labelling for LSD/ULSD; apparently many stations (especially small ones) aren't labelling the pumps properly.

The Detroit runs most poorly on ULSD. It runs audibly better (i.e. smoother and quieter) on LSD, and even better than that on B-20 biodiesel. The PSD runs noticeably quieter on B-20. (With Cat and Cummins already on the B20 bandwagon, it's only a matter of time before Navistar does the same.)

I have noticed that in the Austin area, some stations are not clearly labelling their pumps as to whether or not they're running a biodiesel blend.

I'm marginally curious as to how many diesel pumps there are at the stations you buy at, and how much diesel they go through in a week's time... Any station within about 10 miles of I-35 *OUGHT* to be running enough volume to keep fresh fuel, but you never know... From habit, I have difficulty buying from any station with less than 4-6 pumps...

-blaine

 

The station that I've seen 13s/14s MPG is Valero off I35.. Think its street is Rundburg.. It's 1 exit past 183 heading north.. They have 10 pumps and 4 of them are Diesel.. I don't know if Valero uses Biodiesel mix.. Don't think they do..

 

The unfortunate thing is that there aren't many truck stops in the Austin area, places that have 8-12 diesel pumps, that go through 3-5 truckloads of fuel per day... That's the kind of fuel I prefer to buy if I can at all get it...

-blaine

 

Your right.. Closest truck stop north from me is Waco.. Flying J.. From Waco south to about San Marcos there isn't anything but those rinky Exxon wanna be truck stops.. I hear truckers on the CB all day long bickering bout there being no truck stops in the Austin area..