352 miles on 29.6 gal.=11.9 mpg Help!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Diesel Dan]

65% city(not bumper to bumper either) 35% hwy (70mph avg)

have been noticing bad mpg for a while but was too scared to actually check Checked iat was clean as the day if was installed. currently 28k on od tow apx 8k 6 weekends a year at 9 mpg @ 60-65. 40 psi in bfg's empty Truck runs fine and starts everytime on first try.



Can any one help before i braekdown and go to DC



All ideas big and small very much appreciated



Thanks



DD

 

[Mactruck]

With those big tires your Odometer is off. You probably put on about 400 miles not 350. plus you have the 4. 10 gearing. That makes the cummins run @ a higher RPM, plus the lift kit (kills the aerodynamics) plus the Bullydog propane doesn't help either.

With my driving being 50% on backroads you do not see terribly great mileage. When I run 70 on the highway for a stretch I'll get 20 but on the backroads mileage suffers.

 

[Diesel Dan]

Kevin,

Thanks for the reply. The 352 miles is calculated with the 9% addition for the spedo correction. (actually 323 on spedo) and with 4. 10 and 35 inch tires = 2000 rpm @ 70 (about perfect by most guru's recomendations)unfortunatly i dont have propane as i understand this helps mileage. as far as lift kit goes the fact that i have a cab high shell should negate the lift's aerodynamic disadvantage. Again thanks for the reply but wanted to clarify for all who can help



Keep um coming



thanks



DD

 

[KatDiesel]

How many miles on the truck? Last time fuel filter was changed? Air filter?

 

[Diesel Dan]

Katdiesel,

28k on the odometer, fuel filter changed @ 21k (2-16-01)

And the k&n was serviced by me 2wks ago(have been running k&n's for 12 years in everything that i own )

Thanks for the reply



Also did you get my e-mail in ref to the pictures(the file size was too large 5000000)



Thanks

DD

 

[KatDiesel]

Why not change out the fuel filter just for a peace of mind? Its a long shot but be nice to see what the old one looks like? Maybe some bad fuel?



I only have 285/75/16 and I get maybe 14mpg if I am lucky, but I drive it very hard.



Yes I got the email, I am trying to figure out how to explain it to you best. What mail service or ISP you use? Was it telling you its too big on my end? Or your end?

 

[Archive]

IMO, the big tires and the lift kit are part of the problem. The cab high shell is also a factor... I personally don't believe it negates the lift's disadvantages... you are still higher in the air. And you catch more wind from the sides.



The 4. 10s aren't really 4. 10s any more with your bigger tires. Besides, I break 20mpg on the highway with my 4. 10s, as long as I hold it under 64-65mph.



Have you checked for boost leaks? Check your turbo hose clamps first. How is the basic power of your Ram?



I agree with the fuel filter change... maybe you got some bad fuel and it is clogged already.



Here is something I always post... got it from a Cummins newsletter...



for economy, stay between 1800-2000rpm, for towing/torque stay between 2000-2200rpm.

 

[Diesel Dan]

Hello Rob

Thanks for responding

it has been 3 months since i checked the turbo hoses will do so tonight. The truck runs great and has lots of power just guzzles a little too much #2 will change the fuel filter. should this be done in conjunction with changing my banjo bolts(thanks ray t ) as i understand i have to crack a few injectors to start after install of bb's who has the best price on a filter other than my local dealer $ 45

Thanks again to all



DD

 

[DAWG-1]

I am running the same, 4. 10s and 315s. I was not impressed with my mileage until I replaced the IAT sensor and added 11% for the tires. I went from 13 to 16 The best of 16. 9, I was running with Piers, Chris from BD and Dave back from Timberline, my speed limiter kept slowing me down . I was expecting minimal mileage on that run. 7700 miles so far. I would do what

Rob said and call Cummins and have them send you a new sender. Sam

 

[Ross]

bad mileage

Dan:



My truck in stock form would get 19. 5 mpg on the highway, ranging down from there according to speed, load, and stop & go's. Towing (23,000 gross), I would get 11 mpg, although low power was a serious concern. I then installed Bosch 275 hp injectors, and mileage went up to 21 mpg highway, and towing went to 12 mpg. The hp bug had bit me and I then jumped to the DD stage II's. I don't know how they compare to your Bully Dog II's, but mine really added amazing power, and amazing smoke, and I lost a bit of bottom end torque (below 1700 rpm). All this was fine and good, but my mileage has dropped to 18 mpg on the highway, and 8. 5 - 9. 5 towing 23,000 gross. What I'm saying is, I think your injectors are hurting you. Your auto trans probably isn't helping any either, especially in town. Some Bombing can be done without adverse effects on mileage, but beyond a point, the mileage begins to go the other way You want to play, you gotta pay.



Ross

 

[Alan Reagan]

Diesel Dan,

Here's some things I just did for a guy here who was getting lousy mileage. His mileage immediately went up 1. 4 mpg and that included some hard acceleration where we were troubleshooting a second problem.



http://www.setdr.org/bm/general_diesel/messages/10566.shtml#0



This is a start. Also, try some Stanadyne or similar additive for a next step.

 

[Adam_Dodgezilla]

Not that far off!!

I have around the same mileage I went 940 mile trip to pick up that camper shell and I averaged 12. 9 mpg and that's at 70-80 mph the whole way I used almost 78 gallons of fuel so I believe that the height of the truck and the increased drag of the lift kills the mileage I can get the mileage into the 16's and 17's if I drive 60 mph, But I can't stand to drive that slow!

 

[Thomas]

Try here for the filter:



Cummins Cal Pacific Inc.

1939 Deere Avenue

Irvine, CA 92606



Phone: (949) 253-6000

FAX: (949) 253-6080

 

[Diesel Dan]

Alan

Thanks for the info

what is a thrister(sp)

and what do you mean by entire intake system please elaborate



Hey adam dont forget your truck has to lug around 6-3 300

thats got to be worth 1 mpg right there









Thanks to all



DD

 

[Alan Reagan]

Did I mispell thyristor? It's a variable resistor whose resistance changes with temperature. That's what makes the sensor sense.



Looking at the engine from the front, the intake manifold is on the right. Down both sides are bolts tying the top of the manifold to the block. I believe they are 10mm but can't remember. Those need to be torqued to spec (I believe it's 18 foot lbs). Pay close attention to the long ones going through the plenum that connects the charge air hose to the intake. Then tighten all your clamps on the charge air system. Pay close attention to the ones connecting to the intercooler. You know, the ones that are hard to get to down at the bottom by the radiator. Make sure the hose is slid on up to the stops (you'll feel them if you can't see them) and then snug up the clamps.



That was worth 1. 4 mpg on that 99. I'm sure Quinn's mileage will get better now that he's settled down and gotten used to the new power. The power was very noticeable to him when he drove it.

 

[KatDiesel]

Originally posted by Diesel Dan

who has the best price on a filter other than my local dealer $ 45

If you can wait a couple days order one from Geno's Garage. $15. 45 from Genos, and wonderful service. I been ordering alot of stuff from them lately, always shipped right and perfect. Or try your local Cummins establishment.

 

[Archive]

I was down town and also thought of the tire pressure... you might try pumping them up a bit more for mileage. Don't go so much that they wear excessively, it would defeat your purpose!

 

[SteveH]

Because of the fuel situation in places, some companies are blending a little #1 with their #2 right now. If you have gotten some of the #1 mix, you have fewer BTU's in the fuel and the MPG will suffer. Just another possibility.

 

[NVR FNSH]

Check your correction factor

Not to make you feel any worse but using 9-11% for the tire correction is too high. I have 315/75R16 Americas Tire Pathfinder ATRs w/4. 10 and the odo is only 5-6% off when checked against my Garmin III+ GPS. I'm averaging 15. 8 mpg over ~29k miles - combined city & hwy. I typically drive 70-72 mph on the hwy.



Brian

 

[Big White Beast]

Lousy milage, Hmmmm?

Thought mabey I was the only one suffering.

I get 10. 5 with a mix of city and highway driving and a pretty heavy right foot. GVW is only 10,500 so it shouldn't be that bad. Only have 11K on the beast now. I was hoping it would settle in and start improving. I did change out the IAT but to no avail. I guess I will look into tighening everthing on the intake.



Gauges go in this weekend so I can set a base line and then the EZ. Hopefully if I have a little more power available I won't have to kick it out of overdrive to climb even the littlest hills. That in itself will probably help out.



Aerodynamicaly(sp) I know the utility bed doesn't help but I still figured the truck would give me around 13 or 14 MPG



Hopefully the mods and some more break in time will get me up there.