Engine/Transmission (1998.5 - 2002) HELP! Poor Mileage w/2001 Dually

[HeavyHauler]

I have a 2001 Ram 3500 Quad Cab 4x4 with the 3. 54 rear end and 5-speed transmission. It has just over 60,000 miles on it and has always been serviced regularly. Just switching from a Dodge 360ci gas pusher, I was looking forward to some better mileage and less frequent fill-ups. Unfortunately, I have found that the apparent fairy tales that float around about the 3500 CTDs getting 20 MPG and above are just that.



My truck stays below 16. 0 MPG consistently (always empty - no loads) even with well over half the tank ran out on the interstate and highway. In reality, I probably have never gotten close to touching 17. 0 MPG. I also keep the A/C OFF 97% of the time. I am a fairly conservative driver, so I don't think that my foot is the problem. I also just installed a new K&N air filter, and the fuel filter was replaced just over 6,000 miles ago.



Is there anyone out there that has a similar rig and is experiencing the same problems or anyone that knows anything about it?



Granted, this is one of the heaviest trucks that is available in the Dodge market, but 16. 0 MPG with all the factors listed above is a little hard to swallow.



I have read many articles and heard people talk about larger injectors from Bosch. Do these injectors really help the fuel mileage considerably and do they noticeably increase power? I have seen many different models, ranging from 275s, 300s, I believe all the way up to 375s. Which models are recommended and which yield the best results for the money?



Please help with this problem and if anything, would someone put the 20. 0 MPG and up myths to rest about the duallies?



Thanks for the help.

 

[jrandol]

I did see about 1 MPG consistent increase with RV275's in my 02 2500. That might help some and give you a little extra power too.



Jeff

 

[JBlock]

RV275

RV275 seem to improve the performance and the mileage as well on my 2001. Wife real like tem, not as much hit as the easy but real sleth. Oo.



JB

 

[Turbo Tim 1]

I got 18. 22 mpg once with mine with 4. 10's, usually though it's more like 14-16 mpg because I tend to have a heavy foot and like to leave the comp on 5x5. The first thing I would change out is the Intake Air Temperature sensor, they cost between $20-30 depending on your dealer and when I put a new one in I usually gain 1-2 mpg. The other thing is how you drive, if you go 75 mph don't expect better milage, you are driving a barge, if you go 65 mph you'd do alot better. Change the IAT and see what happens, then change injectors.

 

[dresslered]

I've always run between 15-16 unloaded (fast 2000 ft. climb twice a day though).

 

[RedRam1]

HeavyHauler,



As others have stated, anything over 65mph will knock the socks off of your mileage. On my 2500 4x4 I can get an honest 21 mpg on 100% highway driving at 65mph. If I kick it up to 75mph I'm down around 17mpg which is also what I average in mixed city/highway driving.

I've also noticed that pulling even a light load kills the mileage. I get 16 - 17 mpg pulling my bassboat ~3500lbs at 65mph. It is surprising that the boat extracts such a mileage toll because you literally cannot even tell it's back there. Pulling a 20" triple axle trailer loaded with a farm tractor & eaquipment (~12K) really knocks the mileage in the dirt, around 12 - 13 mpg.

I've got an EZ and RV injectors, neither made one bit of difference in mileage.

 

[swampfox]

My experience driving over 65 Mph is similar to those who prevoiusly posted. Pulling a trailer with ATVs back fom my cabin at freeway speeds (75mph) I got an even 16. Later on another trip, no trailer, local highways,(60-65 mph) I got 20. 0 mpg. Last time I towed my RV, (29 ft Sunnybrook), I got 14 on the way out and 13. 5 on the way back.

 

[WadePatton]

Gauges are handy for MPG too. #1 you get to see if the LP is running, #2 you get to make sure you're getting proper boost and KEEPING it LOW for MPG, #3 You make sure you don't lug the engine (EGT's will climb) while driving around slow and underboosted.



I manipulated 22. 5 out of mine once (at 70). Real highway miles (at 80 or better) I get mid 19's. Normal mileage -rural highway/small town I get 18. 5 AVG.



Except for the first three fill-ups with the DD3's as I dipped all the way down to 18. 0 and 18. 1 Now that I've dynoed and have showed out enough, I'm going to try for some more good MPG numbers.



Other basics--tire pressure, brakes-bearings, dump the muffler... OH and you can check the IAT readings with a OBD2 tool to see whether or not it needs replacing. But don't pay to have it done--it's cheaper to replace it.

 

[Mtngoat]

My truck with the listed bombs got its best milage from Greeley Colorado to Lawrence Ks last month. I got 18. 1 driving at 70, with the A/c on for half the trip. That was unloaded with the cruise set the entire way. Usually I get high 16's, low 17's. Mine is a 4x4 dually with 3. 54 gears and an automatic. I also wonder about duallys getting 20 plus mpg. I guess driving 60-65 might do it, but I have to get places in a hurry seems like.



Robin

 

[CFAR]

I've gotten as high as 21. Worst mileage was towing my enclosed cargo(10-11k) from Mass to CA, high on that trip was around 14, low was around 9, at 75mph with the arerodynamics of a brick what can you expect. Got to keep it below 70, my truck seems to like 67 for some reason. You can also try to clean the IAT which with an exhaust brake needs to be done every once in a while.



Guages will help.



Do you have an exhaust brake?

If so clean the IAT, otherwise clean or replace IAT. It might not set any codes, might just be slow.

 

[hdtrukn]

Quest for Mileage

Here"s my 2 cents.

Up front, I am 2wd not 4wd. But I am running 4. 10s with automatic trans.

I usually always stay above 20mpg, just got back from Fla. saw 23. 2mpg several times. Thats cruise set @ 70mph, maybe 72mph.

I had problems with mileage for over a yr, dealer had no ideas.

I had dropped to 13. 2 to maybe 15. 5.

Here comes the new lift pump. Back up to 17. 2mpg.

Next was 275hp injectors, 21mpg is no problem.

I am thinking I had a bad injector.

Put some new shoes on her,as in tires. I had michelin 215/85/16

A/S went to 235/70/16 A/T michelins lost 2. 5 mpg.

Went back to 215/85/16 michelin M/S back up to 20+mpg even in town.

Conclusion, if you have and dont need A/T tires lose them.

If you are running wider than stock, lose them.

I run 70 psi front, 65 psi rears.

Before anybody jumps me for that comment, this is my personal findings with my truck.

Next put in 275hp injectors, you'll love them. less than $300

installed.

Sorry for long post.

 

[AMF]

mpg

I thought I had the same problem with my 2002 3500 dually. 3. 54 6spd. I thought I was doing every thing right for mpg. So I e-mailed cummins. They told me to shift @ 1400 rpm's which is peck torque for the mighty ISB 5. 9. Over that your just spinning the engine. They also told me not to accelerate slowly. And to shift @ lower rpm's for lighter loads. I don't drive over 60. And now have jumped from 17. 5 to 19. 5. I was truly impressed with this jump. Since that I have installed a BHAF. lost the resonator and muffler and installed high flow muffler. I now get a hair over 20 mpg. That's no BS.

 

[DDT]

The best I have got is 17. 2 Normally it runs 15. 5 empty, I do drive 70, RPM is about 2400. But I do have mud tires on the back. I clean the ATI, it was nasty 1 Made no difference. EZ made no difference in mileage ether.

 

[RED HOT WELD]

WOW! Now I feel even worse,my 01 with 410 rears,auto gets only 11mpg! With some extras on it, Oh ya the truck scaled out at 14. 000lbs!! If you saw it at Muncie on the dyno,you will know what I mean. Mark

 

[RBlair]

I have the exact truck, completely stock and avg 17-18 empty. That is daily driving 50 miles one way, all but 6 is interstate. The last 10 miles into town is regular heavy stop and go intersate back up traffic. I don't baby it but it's not WOT either and I shift anywhere from 2000-2400 depending on the monent. I run the AC most afternoons and some mornings.



I do run treatment every tank and amvery carefull where I buy the fuel. I have run a tank ot two that got really bad mileage and low performance and now stay away from that station.



Roy

 

[MKresch]

I have a '99 3500 dually 5 speed w/ 3. 56 gear, all stock. I get 20. 5 mpg doing 70 w/ air on. the best i've had is 23mpg doing 60. the worst i've had is 15 mpg towing our 30' camper. i want to bomb it but i'm afraid of putting my mileage in the crapper! i think i'll leave well enough alone for now.

 

[OTRPU]

I log my fills and miles daily, loaded and MT, can't break out one or the other the way I do it, but I average 17.



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Regards,

Steve J.

 

[WadePatton]

Where you at HeavyHauler? I'll be glad to test your LP. I'm near Woodbury.

 

[HeavyHauler]

I'm in Memphis through the week and on some weekends, but mostly in Middle Tennessee on the weekends - Hohenwald to be exact (70 miles south of Nashville).



You'll have to excuse my rookieness, I assume the LP stands for Lift Pump? I don't have a great understanding of the lift pump, but if you're willing to test it out, I'll be sure to know enough about it by the time I get you're way.



Are you anywhere between Memphis & Nashville? Anywhere east of Nashville would be hard for me to get to.



Thanks for the offer, hope to hear from you.

 

[HeavyHauler]

Disregard my statement in the 3rd paragraph. I found out where you are located and I'm going to be in Murfreesboro in 2 weeks. this will be the weekend of the 20th (Saturday).



I could probably get over to Woodbury on Saturday if you are willing to check me out.



Send me a PM with an email or get in touch with me somehow so we can work out some details.