Newbie with mileage question

[sodomoto]

Hi guys,

I'm proud to say I just bought my first CTD. I had a 1996 GMC crew cab, dwr,4x4 with the 6. 5 diesel that I loved but she hated. After several years of listening to her gripe I let her talk me into a 2003 Chevy 3/4 ton x-cab with the 6. 0 gas motor. Hated it!

A couple friends have the CTD's and love them, always bragging about 20+ mpg,longgevity etc. . So I went out and bought a 1998 3/4 ton 4x4, x-cab, auto. LOVE IT! But after 2000 mostly highway miles (70mph) I'm only getting 15. 86 mpg. What is going on here? The truck is as follows;

1) 1998 3/4 ton 4x4 with 24v cummins, auto with O/D

2) DRE rear axle spicer 70, anti spin (gear ratio?)

3) 3" exhaust

4) K&N air filter

5) HX35w turbo

6) 285/75/R16 "wild country" m&s tires

7) 104,000 miles

Any ideas and comments greatly appriciated and respectfully considered



Thanks-Mark

 

[BTighe]

first off, welcome home

my milage depends on how im driving. i usualy get about 15 with the trailer in the city. this last tank i got 12 @2. 47per gal #@$%!



are you driving with your foot in it alot. that will kill milage. check fuel filter and other maintinence items, it may help.



i hear ppl tell me they get 25mpg before. ask your friends if thats the best or a real world figure. most go down to 18 or so. good luck either way. hope ive been helpfull

 

[Kennywould]

Sounds like 4:10 gears, once your over 65 mph the mileage will drop. I'm getting 18-19 mpg with 3:73 gears on the highway, above 65 it will drop off to 16-17, then downhill slide from there to about 14mpg at 80mph.

 

[sodomoto]

Thanks guys, keep them cummin

Is there a plate or something that indicates axle gear ratio?

Mark

I forgot to mention; I drive like an old lady. Cruise on at speed limit, passed by V. W. busses around town.

 

[Hvy-DCZ]

Welcome! Glad to hear you ended up with a real diesel. I got my first CTD in August. Absolutely love it!!!



On mileage: I consistantly get 15. 5-18 mpg. I'm mainly running empty commuting around town and a lot of stop and go on the freeway. That number is not corrected for tire size. Stock on my 96 was 245/75/16s. I'm running 265s, so my odometer is ~3% under, so mileage is ~3% higher. Running 285s will be ~6% or more if your rig wasn't adjusted.



Around town, keep the OD locked out so you get TC lockup in 3rd. You'll do best to not to lug the motor. On the freeway, you'll burn a lot less fuel if you stay closer to 60 than 70. It's hard, but better on the fuel consumption.



There should be a metal tab on one of the diff cover bolts that will have the ratio stamped in.



First upgrade should be guages, pyro and boost at the least.



Happy motoring,

Hvy

 

[CarlJensen]

If you take the VIN to the local dealer he can give you a build sheet for that truck. Depends on dealer if you get charged.

 

[Bob4x4]

Pm your vin I can decode and let you know what it was built with. Also with 285 tires your speedo will not be accurate unless it has been corrected.



Bob

 

[painekiller]

i have a 99 Q-Cab longbed 4x2 with Edge EZ and an AFE and 4. 10 gears with 265-75-16 tires. i took a trip to N. Carolina from Ohio taking the PA turnpike up and down hills i was traveling at night following my brother inlaw in his Duramax running between 75-85 mph and i got almost 24mpg where he got 21mpg. :-laf



i also took a trip from Ohio to Maryland pulling my race car and got almost 19mpg i would have gotten better but i was following my dad and a friend and they have gas motors and every hill we came to i had to click off the cruise because i would be pushing them :-laf they had to stop every 200 miles for gas and i made it home on a little better than 3/4 tank :-laf they averaged 12mpg :-laf :-laf :-laf

 

[ROGERDG]

I am new to the TCD as of last Oct. Would like to know when to expect milage figures like that. I am getting about 12 in the city. I pull a 32 ft. fifth wheel trailer and only got about 9. 5. This was when it was new. Now i have about 3800 miles on it.

 

[EMurillo]

i get the same milage w/ 2004. 5 ctd 325/600 i am also wondering when i will ge better

milage

 

[MMeier]

Under the same conditions a 3 rd gen truck will not achieve the same mileage as the older trucks. A box that alters timing might help a bit but maybe not enough to make a big difference.

 

[AKAMAC]

For posts #9 & #10 (Rogerdg & EMurillo). There is an ecm flash for poor fuel mileage. Search the 3rd gen e&t forum for more info.



Bad mileage is not the norm, Rogers 32' 5th towing drop in MPG is about normal in the percentage frame. Loss of mileage is usually around 15 to 20 percent for heavy towing. Try asking your dealer about the TSB. Mike

 

[Cigar John]

The ratio is also on the data tag in the glove box. I'm getting 18mpg around town and in the mountains. My friend just took his FURD in because hes getting 14mpg on I-5.

 

[MFenstermaker]

I have had my new 2005 RAM 2500 CTD for about a month and racked-up maybe 2500 miles. These first miles were a combination of a 120 mile daily commute of with 1/2 of that is in bumper to bumper traffic on a daily basis. I averaged 17. 5 miles per gallon on the first two full tanks of diesel and ove 18 on one of the tanks. The 18 MPG was after adding a tonneau cover and keeping the speed to 70 on the freeway. This is with 4. 10 gears. I am quite pleased so far with the mileage and this configuration. On a recent trip to our vacation home I drove the truck at a continuous cruise control speed of 80 and still averaged a little over 17 mpg. Now that the truck in parked in the vacation home garage I won't be seeing much highway traffic nor commuting but am very happy with the mileage so far. In the future I will be adding some kind of kit (Edge or competitor) and a cat-back Maganaflow or Gibson exhaust and will be curious to see what happens then. So far so good. The owners manual says that efficiency will improve as more miles are put on the truck so I am awaiting this.

 

[ROGERDG]

Mileage Tsb

Went To Dealer Here And Asked About The Mileage Tsb. They Told Me There Was Nothing On That. When I Gave Them The Tsb Number They Said To Make An Appointment To Get The Reflash Done. Get To Go In Next Monday. Can't Wait To Get Better Mileage.

 

[FTwardoch]

My '01. 5 with 315 tires on winter fuel gets about 18mpg, with mostly highway driving. Was getting 20 in the early fall. These are corrected numbers for the tire size and the rig has 3. 55 gears, an Edge EZ and a BHAF, as well as being straight piped. It does seem to matter if you're light on the throttle taking off from lights, etc.



Overall I'm very happy with the mileage I get... ... ... ... just not as happy with the price gouging we are getting hit with compared to years back when diesel was LESS than regular gasoline.

 

[J Shocik]

A 3" exhaust?? That sounds strange as most have 4" cat. back. On my '97, there is an option sticker under the hood, actually on the hood at the safety latch. Mine shows the gear ratio. Maybe yours will too. Good luck with the truck, John