help...06' poor MPG

[kah68]

05 4x4 dually G-56

Just checked ( by hand ) mileage from a trip my 05 just completed. 428 miles driven 57 U. S. gallons consumed. 7. 5 MPG! Now we tow heavy and grab a lot of wind, but 1/2 our miles are empty. Our 01' would never get below 9. 5 and would average 12. This truck and high fuel costs are killing me. The only thing I can think of trying is a Rok Tech crank sensor and the free flowing muffler. I am really upset!

 

[Burner]

It's gott'a be something..... I'm sure that many things can alter the over-all MPG but it's gott'a be something from the factory? Maybe the lift-pump is trash, maybe it's the program, possibly a bad set of injectors, maybe the motor was built 'off' one key?



I have a #3 engine, Mexican made... ..... what's yours?

 

[DPKetchum]

Kah68 how much weight and how fast?

 

[RVTRKN]

Hey Burner, have you tried running level unloaded at 70 MPH with computer reset at 70 MPH just to use as a referance. Mine was getting around 19 avg. and at 75 it was 18. Oh by the way my work truck is a duraflat, I'm only getting 8-10 mpg with a service bed weight of 4000#. The company chose this truck. It is a 05 3500 DRW with an 11' service bed. This is hand calculated, for my truck has no computer. I'm not happy with it's performance, maybe its the allison trans, but there is no power at the top end

 

[Burner]

My MPG thing really doesn't work. If I reset it @ fill-up it goes to "blank-nothing" and pops back up @ 12. 3 or where ever it was reset. I cannot remember resetting it but I'll give it a try tonight.



BTW, I set the cruise and traveled about 350 miles unloaded..... still 12. 5. Checked by computer and by hand, only . 2th off.

 

[RVTRKN]

Burner Try resetting computer when cruising, the reason it shows blank parked it sees no avg, low mpg or city traffic is because it takes an avg. over time so if you reset while crusing it takes that average. Since you never change speed it only sees the avg. at that speed You should see different avg at different speeds. This may not be exact but I,ll bet its close. What has the dealer done or have you taken your sales rep. on this method? I had an emergency brake issue that the mech said was OK. I talked to my rep. and had him use the E brake on mine and a new truck. He talked to the service manager and found a stripped adj. nut. However that was my fourth truck purchased through him.

 

[Burner]

I'm headed to the store... ..... just to drive my truck.



I'll take the Loooooong way a see how it does on the Big Top.



... ... ... ... ... ... ... ... info soon



edit: tire pressure is 65, all around and speed will be @ 70MPH @ 1,900-2,000 RPM.

 

[Donniey1]

Just got my 06 a week ago. This fuel mileage sucks. I am getting 14 mpg. I do not have meny mile on it yet but I am wishing I had my 2000 back.

 

[Burner]

Ok, I'm back. I got the o'le gal up to temp and left the house. I set the cruise @ 70 and reset the MPG thing... . didn't do to well as It showed the same 12. 3, again, again and again. I found a long section of "down hill" on the Innerstate and reset it three more times, finally getting to 13. 7 MPG. As I continued it began to drop and finally resting around 13. 5 MPG. I keep my RPM's "below" 2,000. I'd say the RPMs were @ 1,925 or 1,950 going 70. Oh yeah, my drive was 27 miles, 20 of which were Innerstate. The AC was off and the outside temp showed 59 degrees F.



I have never been passed by so many cars and trucks..... at night!

 

[kah68]

Kah68 how much weight and how fast?

Trailer is 7500 pounds empty, load was in the 6-7000 mark. Speed is 62-65 mph. The old 01' would ( will ) give 11-12 Imperial mpg with that load. 8. 9 ( IMP ) is pretty harsh if you ask me.

 

[Burner]

Well, I'm off to the dealer and I'm not calling before I go. ... ... I doubt I'll have any good luck but it's worth a try. :-laf

 

[kah68]

That will cost me in and round $ 3500. - $ 4000. per year more in fuel! I would love to have the option of a 12 valve 190 h. p. motor with 4:10's and an N. V. 5600. 11-15 mpg, lots of pulling power! Damn sounds like the good old days doesn't it?

 

[JACummins2500]

how many rpm's should i be running in sixth gear at 75 mph with a 3 73 rear end. 2006 4x4 quad cab

Depending on tire size, roughly 2250-2350 rpm's.

 

[Burner]

I think mine runs about 2,100 maybe 2,200. I'll let ya know when i get back.

 

[JACummins2500]

I think mine runs about 2,100 maybe 2,200. I'll let ya know when i get back.

With stock tires, 2100 RPM is about 72 mph.

 

[Burner]

I check the speed via~ GPS and it's about 1. 5 MPH off, 75 is actually 73. 8 or so.



Crusie set @ 75 yeilds about 2,125 'ish' RPM. I have an Auto... .

 

[ilovetrains]

Depending on tire size, roughly 2250-2350 rpm's.

Must be nice, mine is 2600 at 75.

 

[MasterChief]

I recently purchased a 2006 SLT 3500 2X2 with a 4. 10 rear-end I have about 6000 miles on the rig. My mods are; remote starter, step bars, spray-in liner and bed rails. I drive 30 miles to work each day, some stop and go and about 20 miles’of open-road. Two days ago I filled up and did a mileage check. My average is 17. 5. Last week the wife and I took the travel trailer (30' Coachmen // 7000 lbs) I drove mostly interstate at 65-70 for 1400 miles The average was around 13. 5 MPG. I agree with you there is a problem with your mileage. I’m sure that Cummins would be able to help you out. Usually problems like you are having turn out to be something simple. I would not start modifying the truck in an attempt to get better mileage, you will only be masking the real problem. Don’t get frustrated once you get the situation straightened out you will feel great about your new Truck.

 

[JACummins2500]

Must be nice, mine is 2600 at 75.

The G56 has a slower (higher number) overdrive when compared to the NV5600. The G56 with 3. 73's almost matches a NV5600 with 4. 10's in overdrive (6th gear).

 

[DPKetchum]

Has to be repaired at a Dodge dealer. Cummin will NOT do warranty work on them.