Why does my mileage suck goats?

[jponder]

Rob G> Man I wish I could remember what my mileage was when my ETH was new. i think I might have gotten 16 MPG and it seemed I got just as good pulling my old Bronco II home. I drove real slow home and got 18 unloaded aND i MEAN SLOW. Then I pulled my old 3/4 ton dodge 500 miles and I got 17. 1! And I thought man that is good. Next time I went home KABOOM my mileage just soared I think it happened at 14-15,000 miles.
I say pull something heavy and try to get those rings set; then I bet you will start getting some good mileage.

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2001 ETH/DEE ST 4X4 SPACE SHUTTLE

 

[Michael Hughes]

I just thought I would add my . 02. I bought my truck used with 32,000 miles on it. My overall MPG ave is 20. 0. And for those of you that think that some of us are making these numbers up, I am including my log of miles gone and gallons used. I drive 100 miles a day. I nver go over 70 MPH and about half is at 60 MPH. The best that I have gotten was 22. 2 and the worse was 16. 9.
<PRE>
D a t e Miles Qty Cost Gone Ave O/A
-------- ----- ---- ------ ----- ----- -----
10-11-00 38819 28. 1 43. 56 547. 0 19. 5 19. 5
10-16-00 39416 28. 3 42. 19 597. 0 21. 1 20. 3
10-21-00 39965 26. 9 41. 60 549. 0 20. 4 20. 3
10-26-00 40576 29. 3 43. 99 611. 0 20. 9 20. 5
10-31-00 41190 27. 6 41. 02 614. 0 22. 2 20. 8
11-05-00 41779 28. 4 41. 96 589. 0 20. 7 20. 8
11-10-00 42315 25. 9 38. 25 536. 0 20. 7 20. 8
11-15-00 42804 24. 3 35. 25 489. 0 20. 1 20. 7
11-18-00 43207 19. 9 29. 22 403. 0 20. 3 20. 7
11-23-00 43613 21. 1 31. 58 406. 0 19. 2 20. 5
11-29-00 44131 25. 2 37. 71 518. 0 20. 6 20. 5
12-05-00 44628 24. 9 36. 44 497. 0 20. 0 20. 5
12-11-00 45160 26. 5 36. 78 532. 0 20. 1 20. 4
12-18-00 45607 23. 8 32. 82 447. 0 18. 8 20. 3
12-23-00 46128 28. 2 38. 31 521. 0 18. 5 20. 2
12-31-00 46544 24. 6 34. 23 416. 0 16. 9 20. 0
01-05-01 47032 26. 3 36. 54 488. 0 18. 6 19. 9
01-11-01 47516 24. 4 33. 20 484. 0 19. 8 19. 9
01-15-01 47784 13. 6 18. 53 268. 0 19. 7 19. 9
01-19-01 48290 25. 6 37. 36 506. 0 19. 8 19. 9
01-25-01 48803 26. 4 38. 02 513. 0 19. 4 19. 9
01-31-01 49371 27. 6 38. 73 568. 0 20. 6 19. 9
02-05-01 49888 26. 0 36. 91 517. 0 19. 9 19. 9
02-10-01 50421 25. 3 36. 92 533. 0 21. 1 19. 9
02-15-01 51004 28. 5 39. 86 583. 0 20. 5 20. 0
02-22-01 51512 24. 8 33. 96 508. 0 20. 5 20. 0
02-27-01 52079 28. 2 37. 15 567. 0 20. 1 20. 0
03-05-01 52644 27. 6 35. 88 565. 0 20. 5 20. 0
03-10-01 53106 22. 7 29. 08 462. 0 20. 4 20. 0

Total gas cost 1057. 05
Overall ave 20. 0 MPG in 29 tanks.
</PRE>

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1999 2500 ST LB 4X4 Metallic Red, 5-speed, 3. 54 gears, LSD, camper and tow package

 

[Tilesetter Too]

I bought my 98. 5 used, had it 3 months now, 36K on the odometer. Put 3K on it in 2 weeks all highway, mostly 70 or under. Never got better than 17. I tow 5k trailer every single day around town. Lots of lights. Best ever is 12mpg but I am a fairly aggresive driver. I usually average 10. 5-11mpg towing.

 

[RobG]

I guess some people haven't noticed that while I have 4. 10's, I also have an OVERDRIVE, and that on some of the examples given, I was driving at relatively normal speeds.

The overdrive also hasn't done squat for my mileage.

I think I ended up with a pig for a truck.

Rob

 

[jponder]

Originally posted by Tilesetter:
I bought my 98. 5 used, had it 3 months now, 36K on the odometer. Put 3K on it in 2 weeks all highway, mostly 70 or under. Never got better than 17. I tow 5k trailer every single day around town. Lots of lights. Best ever is 12mpg but I am a fairly aggresive driver. I usually average 10. 5-11mpg towing.

Do you have an Auto. It seems the 24 valve autos really take a hit on mileage. I wonder how much that VB changes mileage. I bet a good bit.



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2001 ETH/DEE ST 4X4 SPACE SHUTTLE

 

[swampbug74]

That mileage is ruff. my 2000 4x4 gets 19-21 on the highway with the 4:10 gears it seems to like 69mph the best. what rear end do you have? that trip computer is okay ,but you should do gallons to miles ratio to get real numbers. in my truck at 80-85 turning 2300-2500 rpms and well suck down some fuel best thing running at higher speeds look to draft a big truck to take the wind off the truck i can ran 80-85 and still get 18-19mph. around town 16-18 mpg depends if i have my foot in it. also make sure you don't have the o/d off.

 

[Rambling]

As it says on the mpg stickers "your milage may vary". It's hard to compare results online. As everyone knows, there are way too many factors that affect milage. We know this and yet we - me included #ad
- still try to compare our results with others.

When I look at my log, my mpg numbers are all over the map. Unloaded, I've had as low as 8. 3 mpg unloaded #ad
(just cruising around locally showing the sites to a visitor according to the log) to a high of 19. 4 #ad
(mostly hiway but still local).

Towing is the same story. The lowest I got was 9. 8 #ad
(hilly terrain in PA, winter fuel) and the highest I got was 12. 1 mpg (OD/OD AND had about 10% local) on the same trip within 100 miles and 10 days of the low last Nov.

These are all calculated values. Even with notes to myself on driving conditions, fuel source,and with/without additives, I still haven't been able to determine if I'm getting better or worse than others, what's the best fuel,or the best additive.

In my normal long winded way, I don't think there's much of a way to compare results unless you were running two identical wheels at the same time, over the same course, using cruise control, yada, yada, yada. Just a thought. #ad

 

[AKDrifter]

I'm getting 15-17 MPG unloaded and 13 with 8' slide in. I'm now at 2950 mi. , and it's really starting to run good. Average highway speed is 65. Still pulls to right, for some reason all the other vehicles I drive seem to pull left now, must be strong left arm.

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2001 2500 QC 4x4 HO 6 speed, 4. 10 LSD loaded enough.

 

[MikeR]

Hey fellas,some guys need to go back and read Rob's signature. He has a 3500QC 4x4 ETH six speed 4:10's and an overdrive unit and Rickson 19. 5" wheels.
Now Rob,I followed your posts a while back when you were waiting for the O/D unit to arrive. I have always said the 24valves do better at higher RPM's (2k-2100),but from different reports it seems the ETH's like it around 1900,and your Ricksons probably put you close to there,right? I feel your O/D may be to low for the efficiency band. Now that your truck is getting more (broken in) miles can you drive for a couple of tankfulls without the O/D engaged for curiosity's sake? You may also want to see if the dealer can reflash the ECM to hopefully 'cleanup' the electronics... what do you have to loose there?

-Mike

 

[JyRO]

I'm one of the guys who posts high fuel mileage, you guys may wonder if I'm stretching it a bit. I'm not stretching it at all. But I also note my, "best," numbers are usually from absolutely ideal conditions. For example.....

I fuel up just before entering the freeway and refuel just off the freeway. 70 mph on the c. c. , at about 1,900 rpm (3. 54's, see signature). Flat level country, very little traffic to deal with. I very rarely slow down while traveling the interstate, therefore I speed up (where the fuel is used more) very very little. Calculated on summer fuel with the tailgate down. Only a 2500, so I have less rolling resistance than a 3500, tires aired up to their, "weighted," air pressures. Totally stock motor. My max so far is 20. 8 mpg.

When I was driving it to work (35 miles, 25 miles country - 10 interstate), I accelerated slowly and ran 60 mph backroad, and 70 mph interstate and got 19. 8 mpg on winter fuel. IMHO, I think it is mostly an indication of the discipline you have instilled on your right foot, and whether its an auto or not.

Rob - Yours does sound like more than just a right foot problem. Keep diggin'. Do what you gotta do to fix it, or you'll just pi$$ away money on fuel.

- JyRO

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Y2K 2500 Cummins ETC/DEE, SLT+, 4X4, Quad, LB, Intense Blue Sport, 3. 54 LSD, rear aux. springs (camper special), sliding rear window, all options except cab clearance lights including agate leather, totally stock engine, silencer ring removed, "stealth," mod to run fogs with high beam. Since everybody else listed their toys, I will too.
1995 Kawasaki ZX6-R (For Sale)
1990 Toyota Celica
1983 Mazda RX-7 GSL (For sale)

[This message has been edited by JyRO (edited 03-12-2001). ]

 

[K_Arts]

RobG - One thing you may try is to take the EZ off and go talk to your dealer about a reflash. I complained about bad fuel milage to my dealer and they reflashed my ECM and PCM free of charge.

Just a thought.

Kev

 

[DavidTD]

Rob,

I believe boost has a direct effect on MPG. See my sig for truck, but I drive interstate 50 miles and two lane for another 12 or so one way M-F. If I keep my speed at 70mph, I usually get about 16 or 17. This with a VA and boost module. At 70 on flat ground, I am usually at 6-9 psi at 2375 rpm. I installed 275 injectors and my boost dropped to under 5 psi in the same conditions and my mpg went up over the last five tanks to a low of 17. 8 and a high of 18. 8. One tank towing at 15. 8 All calculated by hand and in my fuel log.

I would like to see us compare boost levels. Maybe some have loose intercooler clamps, poor waste gates, or something else that is causing the truck to supply more fuel due to low boost conditions caused by boost leakage.

Just a thought.

------------------
David
1998 3500 QC 4x4 5 speed 4:10, 235-85-16, VA CPC via JRE, PS Boost Module, K&N air filter. Emerald Green w/tan leather. B&W turnover ball.
1/4 mile 18. 2 @ 74. 75mph
1999 Exiss 3 horse slant, 4ft midtack, 6ft shortwall dressing.
70k miles as of 6/21/00

 

[Scrmbld4X4]

With my camper loaded, driving normally (without cruise, going with traffic), I get 10 mpg. With the cruise set at 65, I got 12. 3 or thereabouts. Hardly stellar.

Normally with my slide in we're towing the Jeep also, but... we went to Yellowstone last summer for a week. From Cheyenne to Custer I pulled 13. 2 mpg. I was pushing one he!! of a head wind or cross wind, cruise set @ 65 mph. In the park for a week we pulled 17. 9 but I don't count that because the highest speed limit is 35. On the way home we ran 65 again and got 16. 4.

So what's the moral of the story???? Mileage can be affected by alot of outside conditions. If you really want to get to the bottom of it you have to put a little thought into it. Drive it to get mileage and try to do the same thing, take the same route, with the same load, etc. Consistantcy is the key.

With experimentation, speed, cruise or not, gear selection, etc you should be able to find the sweet spot. Mine definetly favors 65MPH (2000 rpm) for mileage. The faster I drive the worse it gets.

Do you have guages? (sorry to lazy to go back and look) Watching the boost and EGT will tell you alot about what's going on. Keep them down and the mileage will go up.

------------------
TOWER: '99 3500 4X4, White, 3. 54 LSD, 5spd, CMPR&TRL package. Glass shell or 9 1/2' Shadow Cruiser slide in. Geno's combo gauge. DynoMAX, K&N RE 0880, Jacob's E-Brake. PUTCO Max Boss boards and Flaps.
TOWEE: '82 CJ-8,Lime Light, Injected 440, 727 T flite, IH Dana 300, Dana 44 frt, Dans 60 rr 4. 88's & Detroits, 38. 5 X 14. 50 TSL/SX's, 15 X 10 Eagle 589's. Full soft top and full length cage.

BIGGER IS BETTER!! MO POWER

 

[PUFF00]

Rob,

Just filled up. 414 miles, 23 gallons = 18 mpg. The computer said 16. 4 mpg.

This was mostly highway. Approximately 40% at 75mph and 60% at 60-65mph. The truck had 750 miles on it when I filled up.

------------------
2001. 5 3500 QC 4X4 6-speed HO 3. 55 black
1998 Jeep TJ black http://www.nm4w.org/members/puffer.htm

 

[Max Wedge]

Well I might as well chime in on this one. Bought my Y2K 3500 4x4 QC Auto 4. 10 in July 2000 and for the first few months I didn't check anything but the "computer", but here is all the info I have on my mileage since November: MPG
13. 60036
13. 77171
14. 33144
11. 21266
13. 07831
14. 49164
13. 87727
11. 76427
14. 04892
13. 30236

This is all driving around town and totally empty. Computer seems within . 5 MPG and when I towed my race car in a 24" enclosed trailer computer said 10. 5-11. 0. This truck is stock except for K&N Filter.

------------------
Y2K 3500 4x4 SLT+ Leather ETC/DGA DMF/DSA Black
'64 Plymouth 426 III
'79 Chrysler 300 T-Tops



[This message has been edited by Semi Automatic (edited 03-15-2001). ]

 

[PUFF00]

Second tank: 477 miles, 27. 3 gallons = 17. 5 mpg.

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2001. 5 3500 QC 4X4 6-speed HO 3. 55 black
1998 Jeep TJ black http://www.nm4w.org/members/puffer.htm

 

[tmacc]

Well mine is finally up around the 15 mpg mark at 18k. I don't know if it's finally breaking in or if PS additive is a contributing factor. Still disappointing. Lucas fuel additive did nothing from a milage stand point IMO. Looking forward to summer blend fuel. It is nice to see fuel down to 1. 45 around here, but I heard OPEC is reducing production next month. Bummer.

 

[Happy Camper]

Ave 15. 05 over 7,000 miles. The best was 17. 5 but I do a lot of mountain driving over slick, curvey roads. Some miles were with a 3k slide in camper and other miles were with a 11k 5th wheel. On one tank I got 20. 1 but I ignored this as I dont't think the attendant filled to neck which I usually do.

------------------
Kimzy Bertalotto
2001. 5,3500 QC 4x4, HO/6spd,limited slip,BD,brake,60 gal Aero tank.

 

[$BANKS$rupted]

this week on a trip to FL and back 20mpg @ 75mph, 90% hwy, with 110,000 miles on rig.

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99' 2500 2wd SLT Auto LWB Quadcab "BANKS STINGER PLUS" (TURBO BACK 4"-STAINLESS EXHAUST, QUICK TURBO HOUSING, OTTOMIND COMPUTER,K&N FILTER, PYRO-BOOST & TRANS-TEMP GUAGES), 275hp RV INJECTORS,PROTORQUE CONVERTER, TRANSGO SHIFTKIT, AIRLIFT "SUPER DUTY", CENTURY "ELITE" CAP (LIMO BLACK ON WINDOWS),BEDRUG, SHELF-IT,PIONEER "PREMIER" CD W\CD CONTOLLER,YAMAHA PASSIVE EQ, ALPINE 200 WATT 4-CHANNEL AMP, POLK SPEAKERS, PUNCH 45 "STRAPPED MONO" (90WATTS) ON 12" BAZOOKA TUBE

 

[Dave B]

For reasons unbeknownst to me and many others, 3500s do not get the MPG that the 2500s do. There seem to be some exceptions, but for the most part, if you look all thru the archives on this site, take comparable 3500s vs 2500s... same year, same engine, same trans, same axle(s), and similar driving habits, and the 3500s seem to be pigs. Strange.