Fuel economy ?

True North · **Joined:** Mon Feb 18, 2013 11:24 pm **Posts:** 3

I have an '08 Liberty sport 3.7L, are there any tips or tools I can used to increase economy ? Thanks

lfhoward · **Posted:** Tue Feb 19, 2013 12:00 am

There are some good tips on Fuelly.com. Some suggestions are better than others.
http://www.fuelly.com/tips/

Basically it's a Jeep so economy is not its strong suit. Before I modded mine, I could get 22-23 mpg on the highway. Now it's more like 19-20 with the skid plates, boulder bars, and roof basket. My best ever was 25 mpg, going downhill out of the mountains with a tailwind. Keeping within the speed limit helps a lot. City mpg ranges from 13-15, depending on red lights and stop/go. Maximize that by coasting and timing your approach to traffic lights so you don't have to stop as often. I also have a Scangauge that plugs in to the OBD port and reports my mpg instantly, so I can see how different driving strategies affect my fuel economy and adjust on the fly.

Gageraid · **Posted:** Wed Feb 20, 2013 7:58 am

I also have a device that tells me instant mpg that plugs into the OBDll port. Really helps keep your foot out of it. Make sure it's running in top condition. Most will just say it's a Jeep, but the main culprit is the weight of the vehicle and so-so 4 speed.
My best advice is keep the rpms low, and try to stay in overdrive as much as possible. Just like lfhoward said, Fuelly.com has some stuff worth reading.

tommudd · **Posted:** Wed Feb 20, 2013 9:39 am

Style of driving
don't let the engine lug down meaning keep the revs up and going. If it goes into overdrive too soon then the engine will lug down and actually burn more fuel
I keep the overdrive locked out around town and back roads runs way better
Some think if you get it into overdrive right away its great, but no

True North · **Joined:** Mon Feb 18, 2013 11:24 pm **Posts:** 3

tommudd wrote:

Style of driving
don't let the engine lug down meaning keep the revs up and going. If it goes into overdrive too soon then the engine will lug down and actually burn more fuel
I keep the overdrive locked out around town and back roads runs way better
Some think if you get it into overdrive right away its great, but no

Doing so by pressing tow/ haul ?

Gageraid · **Posted:** Wed Feb 20, 2013 10:54 am

tommudd wrote:

Style of driving
don't let the engine lug down meaning keep the revs up and going. If it goes into overdrive too soon then the engine will lug down and actually burn more fuel
I keep the overdrive locked out around town and back roads runs way better
Some think if you get it into overdrive right away its great, but no

Yes, but when you're on a long straight, downhill road, overdrive will save you gas.

tommudd · **Posted:** Wed Feb 20, 2013 11:00 am

long down hill well sure then but how many times are you going to have that for miles and miles :wink:

lfhoward · **Posted:** Wed Feb 20, 2013 1:40 pm

I think you're both right. If you have larger wheels, the Jeep may struggle and use more gas in overdrive. On my stock suspension with stock size A/T tires (225/75/16) and stock gears (3.73), I can get 20 mpg on the flat with OD, but only about 15-16 mpg in 3rd gear (with OD off-- Tow/Haul engaged, assuming 65 mph). Now with a lift, larger tires, and 4.10 gears, I'm sure the dynamic changes. :wink:

The mpg numbers above come from my Scangauge and I'm sure the trend is accurate for decently flat interstate driving. But going up hills the OD loses its advantage, and the transmission will kick down into 2nd and overcompensate, using more gas than 3rd gear. So if you're in a hilly area, maybe engaging Tow/Haul would be better.

tommudd · **Posted:** Wed Feb 20, 2013 2:13 pm

Not talking about 65 MPH
We're talking about people running between 0 and 50 or so trying to or letting it get into overdrive and then the RPMs are too low. 3.7s like some RPM to run correctly.
BEFORE I ever lifted / installed larger tires etc , I never used overdrive until I was on the road/ 55 and above
This getting them to shift into over drive as soon as possible is bad for the engine and the mileage

Plus 4.10s gets it back closer to stock running RPMs so it helps either way
People need to stop driving them like a hunk of junk Prius :wink:

lfhoward · **Posted:** Wed Feb 20, 2013 3:03 pm

tommudd wrote:

Not talking about 65 MPH

Tom, Thanks for clarifying. I agree with you!

Bmxer524 · **Posted:** Wed Feb 20, 2013 3:16 pm

It's a Jeep you'll never get any great mileage out of it, so why worry?

Anyways Tom is right(as usual lol) if you're in overdrive as soon as possible you're bogging the engine down. The other day mine decided od was the best at 50mph, boy did the 3.7 hate that. It reminded me of when my grandpa would be too lazy to downshift in his old Ford. The truck would bog and run like garbage(to this day he hates when my dad and I tell him he is lazy with shifting lol). The only difference is the KK was just more subtle due to revving slightly more.

Keep the 3.7 happy and keep the revvs around 2k. About 60-63mph seems to be the "sweet spot" for a stock KK.

Gageraid · **Posted:** Wed Feb 20, 2013 4:51 pm

Someone steal mine, and drive it like a mad man and rev the hell out of it, cuz I never will.

Bmxer524 · **Posted:** Wed Feb 20, 2013 5:36 pm

Gageraid wrote:

Someone steal mine, and drive it like a mad man and rev the hell out of it, cuz I never will.

With all the performance mods you never put your foot down to see if it made a difference?

Gageraid · **Posted:** Thu Feb 21, 2013 6:50 pm

Bmxer524 wrote:

Gageraid wrote:

Someone steal mine, and drive it like a mad man and rev the hell out of it, cuz I never will.

With all the performance mods you never put your foot down to see if it made a difference?

Not as much as I probably should.

tommudd · **Posted:** Thu Feb 21, 2013 7:11 pm

Gageraid wrote:

Someone steal mine, and drive it like a mad man and rev the hell out of it, cuz I never will.

Bring it over for a few days so I can get the cob webs out of it for you! :wink:

You can even ride along if you want :lol:

Gageraid · **Posted:** Thu Feb 21, 2013 7:15 pm

Sounds good! Honestly, I think I got it all out of my system with my previous car that had a lot of horsepower and torque.

If "cob webs" are a real problem, wouldn't be that surprised if I need to address that.

tjkj2002 · **Posted:** Thu Feb 21, 2013 7:17 pm

tommudd wrote:

Gageraid wrote:

Someone steal mine, and drive it like a mad man and rev the hell out of it, cuz I never will.

Bring it over for a few days so I can get the cob webs out of it for you! :wink:

You can even ride along if you want :lol:

I'd offer the same deal but he may not want it back after I "drive normal" in it for 3-4 days.

Gageraid · **Posted:** Thu Feb 21, 2013 7:20 pm

Do whatever you want with it, TJKJ, as long as it comes back with a SFA swap.

BillyP · **Joined:** Sat Feb 16, 2013 11:38 pm **Posts:** 39

I have an 08 with nearly 94k miles on it. Around home I average 17-18mpg. If I get out on the interstate for a trip I'll get 21-22.

Gageraid · **Posted:** Fri Feb 22, 2013 2:22 am

BillyP wrote:

I have an 08 with nearly 94k miles on it. Around home I average 17-18mpg. If I get out on the interstate for a trip I'll get 21-22.

Good to hear someone else getting some decent mileage. Keep up the good work!

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