Who is averaging 30+ mpg driving their Liberty CRD?

UFO · **Posted:** Mon May 05, 2008 3:39 pm

I'm still having trouble figuring out why some get 30 on the highway, and others, like me, who get less than 26. Same vehicle profile, same tire size, same speeds, clean air filter, maybe it's just winter fuel? I'll try again this summer....

Joe Romas · **Posted:** Mon May 05, 2008 7:13 pm

UFO wrote:

I'm still having trouble figuring out why some get 30 on the highway, and others, like me, who get less than 26. Same vehicle profile, same tire size, same speeds, clean air filter, maybe it's just winter fuel? I'll try again this summer....

Me too! Highest I ever got was 25 and that was one time :roll:

But my last tank of all city short trip driving got 21.9 MPG. The same type of driving got me 11-12 on my 4.0L 99 XJ so I'm happy with the city figures. One very possible reason is fuel quality or lack of :lol:

fastRob · **Posted:** Mon May 05, 2008 9:39 pm

Just had my first New Hampster road trip.
It was the first opportunity to get some highway miles in 2 months of ownership.
I did not think it would ever happen, my worst has been 18.9 mpg and now 26 mpg, what a range!

EDit: I did the math wrong , went back and rechecked, corrected, foo!

WolverineFW · **Posted:** Mon May 05, 2008 10:02 pm

fastRob wrote:

Just had my first New Hampster road trip.
It was the first opportunity to get some highway miles in 2 months of ownership.
I did not think it would ever happen, my worst has been 18.9 mpg and now 30.9 mpg, what a range!

Same here....first long road trip today. Almost all on the highway with speeds between 100 to 110 km/h and I averaged 31.4 mpg or 7.5L/100km. Have had the CRD for less than two months....only thing I have done is replace the filthy air filter and bump the tires up to 40 psi.

That being said on the flip side when I am driving in the city with a lot of stops and starts, the worst I have gotten is around 18 mpg.

Bill.Barg · **Posted:** Tue May 06, 2008 12:13 am

One thing not listed is the effect of using the od button wisely to keep the TC clutch locked up as much as practical.
I learned this from Retmil's posts.
If I am in hilly terrain at 45 mph, I will take the OD off, so the TC locks. If I get over 53 mph, say downhill, I will re-engange the OD, and the TC stays locked.
This has a 2mpg effect in the hilly area where I live with 45mph speed limits.

The AC has a very significant effect also. - 1.5 mpg typical

durangotang · **Posted:** Tue May 06, 2008 12:53 am

This range in mileage with the vehicles is pretty strange... I always look forward to driving from Durango to Moab because it is a nice straight shot (slightly downhill) and last time I got just over 34mpg measuring gallons at the pump distance per my Garmin. Watch now... it will drop to 18mpg as soon as I install a lift pump or something haha.

moto-scoot · **Posted:** Tue May 06, 2008 12:59 am

UFO wrote:

I'm still having trouble figuring out why some get 30 on the highway, and others, like me, who get less than 26. Same vehicle profile, same tire size, same speeds, clean air filter, maybe it's just winter fuel? I'll try again this summer....

Mine was getting 26 highway when i bought it a few months ago.
ive done these.
1- aligment
2- ORM
3-new front wheel bearings
4- new rear calipers & hoses

now getting 29 - 31 mpg
the wheel bearings & rear calipers were the best improvment.
they were done together
make sure them brakes arent dragging esp when their HOT

5-Duct tape rotten egg to top of you gas[?] pedal :lol:

dirtmover · **Posted:** Tue May 06, 2008 9:25 am

Threeweight wrote:

....the wind drag is just too bad, and they weigh too much. I'm going to start lightening up a bit on what I haul around in mine all the time.

Yeah, same here. First thing to go is going to be about 50lbs from around my waist. :oops:

warp2diesel · **Posted:** Tue May 06, 2008 1:32 pm

....that allow higher operating pressure work with out screwing up the suspension :?:

If so, spending the extra $50 to $75 for LT tires would help get more out of each gallon of fuel.

Please let us know if you have installed LT tires that work well.

ATXKJ · **Posted:** Tue May 06, 2008 1:48 pm

Many folks have gone to 40psi on the stock tires - and it will increase mileage.
however to go to LT tires - will normally add 10-15 lbs of weight per tire - so if you do stop and go driving - that will reduce mileage.

and my standard caution - increasing pressure reduces the contact area of the tire - so at a maximum traction panic stop - the stopping distance will be greater.

Desert_Busa · **Posted:** Tue May 06, 2008 9:46 pm

The sidewall says 44psi max. That's is what you'll find in my tires. At the speed I drive braking change is negligible. It may make a difference on the ice, but I haven't noticed. The tires have been wearing evenly since new. Now with 37k, these goodyears are starting to grow on me

danoid · **Posted:** Fri May 09, 2008 9:20 am

1. What speed range seems to be the most fuel efficient? - 65-70
2. Do you have the F37? - Yes
3. Are you running a programmer or module? - No
4. What tires are you running and what PSI? - Michelin XPS Rib 65 psi.
5. Tire size? Stock
6. What air filter or air intake system are you running? - stock
7. What exhaust are you running? - Stock for now.
8. What kind of fuel (100% biodiesel, #2 diesel, or blend)? - #2 dino
9. Fuel additives (Power Service, TC-w3 2 stroke, etc.)? - None
10. Extra weight (skids, rock rails, bumpers, winches, etc.)? - Mopar Rock rails - 20T hydraulic jack in back - 12V compressor - a few tools.
11. Wind resistance (lift, roof racks, etc.)? - Mopar light bar
12. Engine oil (synthetic or non-synthetic)? - Delvac 1
13. Engine oil weight (5W30, 15W40, etc.)? - 5w40
14. Suncoast T.C.? - Not yet
15. ORM? - I for one, am happy to live in a country where the EPA still lets me breathe.
16. Lift pump? - no
17. SEGR? - I for one, am happy to live in a country where the EPA still lets me breathe.
18. Other factors? - lock it up in 3rd with OD off button as much as practical (amap) - shift to Neutral when stopping (amap) - coast to slow down on freeway instead of brakes (amap).

A good mostly freeway tank will get me 24-25 mpg in summer. I've hit a max full tank of 27. Usually however, in the summer if I'm driving a long distance I have a 27' camper behind me and then I'm happy with 13-14.

StarDreamer.us · **Joined:** Fri Oct 06, 2006 9:15 pm **Posts:** 63

My mpg after the f37 or was it the f31, recall has gone into the trash. Now around 17 - 18 highway ar 55 mph. All things have been cleaned and new filters. Any ideas??

Jim Friese · **Posted:** Fri May 09, 2008 12:01 pm

My CRD has the following.

Skids Engine, Tranny, Xfercase
Cross Bars Stock
Provent
Tries Stock
Fuel #2 Dino
Oil 5w-40 Shell Rotella Syn
Filter NAPA Oil
Air Filter NAPA
MPG last check intown 21.9
Hwy. 25.1
Hwy Speed 65-70 MPH
I think that we are still using winter blend. I will check again in June.

ATXKJ · **Posted:** Fri May 09, 2008 12:02 pm

StarDreamer.us

55 is not a real good spot post F37 - you're in 4th gear (should lock up about 51-52) and it won't go to 5th until you're ~62.

however that shouldn't cause 17-18 that's what I got in town with lift/MTR's and steel bumpers.

I'd start looking for mechanical issues - i.e. brakes dragging? - did you clean the MAP sensor? - do you have the EHM or Provent? - you may be getting oil buildup in the intake.

If the timing is exactly with the F37 - maybe they did something wrong - not enough tranny fluid was common since the paperwork told them to drain 4 quarts but only add 1.

donlvnv · **Posted:** Fri May 09, 2008 7:07 pm

After doing my PEGR with Dennis's help I clocked 31 mpg going to Albuqerque today. Thanks for the help Dennis!

danoid · **Posted:** Fri May 09, 2008 8:37 pm

StarDreamer.us wrote:

My mpg after the f37 or was it the f31, recall has gone into the trash. Now around 17 - 18 highway ar 55 mph. All things have been cleaned and new filters. Any ideas??

EEK! Is your torque converter locked? When you reach a small hill does the rpm change? If you tap the pedal lightly does the rpm change? If you answer yes to either of these, you may have to increase speed 1 or 2 mph to lock up the torque converter. That's an instant 10% increase. How about filling out the question list, that may give someone a hint at what to look at.

Sergio del Castillo · **Posted:** Sat May 10, 2008 1:53 pm

I have been checking my CRD milage since new (Feb.05) and it improved after the first 12K mile or so. My commuting was 16 miles one way Washington DC suburbia area, average 45 minutes drive, average MPG 16 to 17 new 18-19 after 30K plus. Long vacation trips during the summer, to New Hampshire, To Arizona, to Oregon, several to St. Luis MO. Loaded with daughter's stuff from college, a mattress on the roof, and pulling a 1,700 LB. trailer through the Appalacian Mountains Average to 22-25 MPG. With out trailer but with 3 people and luggage, 23 to 26, some times 27 MPG. Best milage ever, one tankfull on an strech on northern Michigan 29 MPG. All of previous information is running stock, standard ST tires, 33 PSI, roof rack, engine-transmission and transfercase skid plates. Milage was calculated, no onborad computer. All reflashings made. Use Mobil 1 0-40 oil an change it every 6,250 mile or so.

After the last trip last summer, before going to Camp Jeep, I had installed ARB air lockers on the rear and changed to MUD tires, BFG's. Surprise. Milage droped 4 to 5 MPG in the commutinmg drive and 3 to 4 on the highway. I am getting now 13-16 in commuting drive and 20 to 22 highway. I had the truck checked at the dealer and after some sensors replacement and cleanup of the CAC pathways, better driving but little improvement on the milage. I was expecting some milage drop from the tire swap but really not that much. I am working now at a different location, only 7 miles, all in city traffic, so I will not have a good reference point for commutin milage, just the highway milage. Now compare that to the gasers 10 to maybe 15 MPG, and lower emission of polutans, that still is a better deal. It is easy, you move so many pounds, for so may miles and use so much fuel.

I honesty don't know how it is possible to have your tuck to drive confortable, at 65 plus MPH highway, and still get 30 MPG. Diesel engines are designed to work hard, at least 80 % loaded, otherwise the built up carbon in the combustion chamber, if you "nurse" a diesel engine to obtain the highest millage possible you are not using the engine they way they are designed to be used. 44 PSI on your tires? that it is rough on your kidneys. I always said that MPG is not the best way to define engine efficiency. Miles-pounds per mile would be a better measurement.

fastRob · **Posted:** Sat May 10, 2008 2:03 pm

Sergio,

To me it is a money game.
I want the most for the least money.
When I started the mods I was surprised! There is real potential for power and economy.
Like a good woman that can work hard, be fun and not cost an arm and a leg.
This is also an alternative energy choice for me.

CATCRD · **Posted:** Sat May 10, 2008 6:53 pm

Sergio del Castillo wrote:

Diesel engines are designed to work hard, at least 80 % loaded, otherwise the built up carbon in the combustion chamber, if you "nurse" a diesel engine to obtain the highest millage possible you are not using the engine they way they are designed to be used.

This is true for conservatively rated engines that will see continuous duty. For example a 15L semi-truck engine has 5.35 times the displacement of ours, but it doesn't have 5.35 times the power rating. That would be 857 hp. It's more like 500 hp. Our engines are aggressively rated and won't have near the life at 80%+ load.

Who is averaging 30+ mpg driving their Liberty CRD?

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