Engine/Transmission (1998.5 - 2002) More poor fuel economy.

[jmeehan]

Sorry for the long post, I just wanted to make sure and include all the details.



I get 14-15 m. p. g. driving here on the island, and it hasn't changed. I don't get a real good milage check until I get the truck south, once a year, where I can drive it more then 10 miles at a time.



When I bought this truck new in Nov. '00 I got 18 m. p. g. driving it from Idaho to Prince Rupert B. C.

Two years later, with 15K miles on it, a canopy, big front bumper and 285/75 tires, I got 18 m. p. g. figured by hand and correcting for the tires. I bought a DD TTPM when I went through Vegas and milage went up to 19. I got 20 on two tanks.

One year later, with no changes, milage was down to 17. Since then I've changed injectors twice, first DD II's, then Don M's 1. 5's. New lift pump and clutch. Still 17 m. p. g.

I've cleaned the IAT and checked the MAP sensor with a DRB scanner.

My driving habits haven't changed. I haven't checked the valve adjustment yet.



I've read that there is a break-in program in the ECM. I wonder if the milage dropped when that was de-activated? I've never had a real load on the truck, just run empty or pulled an empty boat trailer. I'm at 48K miles now, I'd think the rings have seated. Other then the milage the truck runs good and makes good power.

I don't think it's the change to winter fuel since all my trips have been in the fall, from B. C. to the south west.

 

[Gary - K7GLD]

"I've read that there is a break-in program in the ECM. "



I think that falls squarely into the "old wives tale", or pure baseless rumor category - never seen the slightest proof or documentation for that notion.



BUT, I wonder if winter fuel, or shifting formulations have reduced your MPG...

 

[PhilLewis]

I also had similar mileage in my '01 auto. At the same time I had code 216 (inj pump timing). I tried everything before I finally bought a new VP44. I found that even though the map sensor tested ok, a new one improved mileage enough to notice. Presently I am up to 18 mpg on a good day and the truck runs better than when it was new. I think the map was $80 from cummins. Good luck.

Phil

 

[slo-ryde]

I get 14-15 m. p. g. driving here on the island, and it hasn't changed. I don't get a real good mileage check until I get the truck south, once a year, where I can drive it more than 10 miles at a time.

I watch the overhead computer while driving, the mileage on my truck is in the same range you mention until the motor and drivetrain gets warmed up. Driving 10 miles in my truck barely gets the temp gauge into the normal range.

 

[jmeehan]

I realize the small town driving milage won't improve. Sure I was disappointed when I first bought my truck, but I've learned to accept it.

I didn't buy the truck to run around here anyway, I bought it for road trips. That's where I expect to see good milage.

I had not thought about different fuel formulations being the cause. I know fuel will be changing for emmisions purposes, but I'd think everyone would be noticing a drop in milage.

I may try a new MAP before my next trip and see if that makes any difference.

 

[OTRPU]

I don't have an overhead thingy, and I think I'm glad I don't. Everybody I know that has one thinks these ton dually trucks don't take fuel to run. I haul lots, know what, I gotta stop every couple days and put fuel in it. Do regular scheduled maintenance and keep the filters clean. Beyond that bout all I can do to get better mileage is slow down. Eight thousand pounds of crap takes heat to move it down the road. . . hang anything on the end of it, it ain't gonna make it get better mileage, almost guaranteed to get less. Fat tires, weight, wind, the more up in the air it is. . . almost guaranteed to get less. Don't make much difference to me what I pay, I shop when I can, but fact of the matter is they got me by the short hairs, a man standing there with a gallon of fuel when I need it can pretty much say what's it cost? Your wife, your first born male child, and anything else you can get ahold of. Wanna lower insurance and fuel costs? We all have lots of control over both issues. Slow down, prolly have fewer accidents which will lower cost of insurance, and you'll go further on a gallon of fuel. This from the only guy on the Interstate System doing the posted limit. And if the limit is >65 MPH I aint'a gonna do the limit even. JMHO



Cheers,

Steve J

 

[2-ND TIME]

Your mileage isn't too bad. With some idle time your mileage might be it that range. mine is and it is very gutless. Warmup time will affect the mpg better to let them warmup then to drive them cold.

 

[jlhartak]

I drive less than 10 miles to work and my 99 5spd just gets warm, I do get about 16+ mpg with stock tires, 4" exhaust and NO extra weight. I have found that diesel quality can vary, I have driven from Alaska to Missouri and one tank of fuel would get 1-2 mpg more or less than the last, driving down the same Interstate! Like the man said it takes a lot of heat to move 6500lbs plus down the road. I feel real good when I compare the 8-9mpg a 1-ton gasser gets!



Regards

 

[Jack in Alaska]

J. Hart

I buy my fuel at Freddies in Anch. or Essential in Bird Crk. In many round trips to Ninilchik from Anch. I have found that Essential gives better mileage, 14 & 15. 5 mpg. Must be the fuel quality.

 

[jlhartak]

Jack,



I fill up at Essential in Bird Creek too, if memory serves the pump says it is a premium diesel with additives. When I can't get to ANC I use FM in Soldotna. I know my mileage goes down and noise goes up when the stations switch to #1 for the winter. I do use Diesel Kleen or Amsoil additives in the winter for better fuel flow and lubricity for the VP44.



Regards,