Optimum speed for mpg and other advice wanted

dgeist · **Posted:** Fri Sep 05, 2014 5:18 pm

I get my best mileage when I'm driving on the highway between 64-68 mph with a fully loaded yakima rocket-box on the roof...I think it creates a more aerodynamic profile

Other than that, GDE helped a point or two. Removing the muffler helped a point or two. Adding the lift and aggressive AT tires dropped it a point or two.

By far, driving habits make more difference than anything else. You can drive a civic like and stupid and get horrible economy and drive a silverado like a hypermiler and get great numbers.

Dan

papaindigo · **Posted:** Fri Sep 05, 2014 5:23 pm

I'll try again. What the GDE site says is "Any Second Engine Tune For Existing Liberty Flash Tool Owners". If you own a flash tool with a first tune then the flash tool is locked to a specific vehicle VIN and is physically incapable, been there done that, of even reading much less uploading any tune (1st, 2nd, whatever) to a vehicle with a different VIN. The 2nd tune "deal" is for current tune owners with a flash tool who want the ability to change the loaded tune on their vehicle from say EcoTune to HotTune for specific driving conditions.

tjkj2002 · **Posted:** Fri Sep 05, 2014 8:11 pm

WWDiesel wrote:

:

I do not believe lifting had much of an effect on the mileage.
Larger tires does throw the speedometer off by a small amount due to the slight change in final gear ratio. It takes more HP/torque to get taller tires up and rolling and keep them at speed, so you need a performance tune if you plan on running a larger diameter tire. :2cents:

Lifting allows more air under the vehicle which increases drag which decreases mpg's.

WWDiesel · **Posted:** Fri Sep 05, 2014 9:37 pm

tjkj2002 wrote:

WWDiesel wrote:

:

I do not believe lifting had much of an effect on the mileage.
Larger tires does throw the speedometer off by a small amount due to the slight change in final gear ratio. It takes more HP/torque to get taller tires up and rolling and keep them at speed, so you need a performance tune if you plan on running a larger diameter tire. :2cents:

Lifting allows more air under the vehicle which increases drag which decreases mpg's.

I think the full skid I made and installed offsets that??? :wink:

WWDiesel · **Posted:** Fri Sep 05, 2014 9:45 pm

npkdm wrote:

thanks for all of the advice. the eco tune sounds great but it is expensive. like 700$. if i only gain 3 mpg on average it would take 50k miles to just pay for it ($3.60 diesel). wouldn't be worth the effort for me. please correct me if my math is flawed. i am interested in a WVO conversion. if i do that i would get a tune as well. i have searched the forum for info on WVO with little result. if you know of a good thread or member for this topic let me know.

a couple of you have mentioned brake drag. i had the front drivers wheel jacked off the ground and it didn't spin freely. it didn't take a lot of effort, but i think the brake was engaged very slightly. the PO installed new front brakes shortly before he sold it. the front brakes are producing a lot of brake dust. how can i tell if the drag is normal? should the wheel spin completely free? like not stop the instant i quit turning it?

There are other options available on this forum if you are willing to try and cost is only ~25 bucks on eBay for a communication dongle if you have a laptop! :wink:

Read this thread on this forum:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=98&t=78418

npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

Sounds like you know what your talkin about papaindigo. Think I'll stick to the original plan and do without the tune. I still feel it is way overpriced.

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tjkj2002 · **Posted:** Fri Sep 05, 2014 11:16 pm

WWDiesel wrote:

tjkj2002 wrote:

WWDiesel wrote:

:

I do not believe lifting had much of an effect on the mileage.
Larger tires does throw the speedometer off by a small amount due to the slight change in final gear ratio. It takes more HP/torque to get taller tires up and rolling and keep them at speed, so you need a performance tune if you plan on running a larger diameter tire. :2cents:

Lifting allows more air under the vehicle which increases drag which decreases mpg's.

I think the full skid I made and installed offsets that??? :wink:

Not unless it has a air darn extending down to the OEM height.Not only does it allow more air under but it also exposes the tires to more air and they add a lot of drag when exposed.

rancherman · **Posted:** Sat Sep 06, 2014 12:40 pm

npkdm wrote:

thanks for all of the advice. the eco tune sounds great but it is expensive. like 700$. if i only gain 3 mpg on average it would take 50k miles to just pay for it ($3.60 diesel). wouldn't be worth the effort for me. please correct me if my math is flawed. i am interested in a WVO conversion. if i do that i would get a tune as well. i have searched the forum for info on WVO with little result. if you know of a good thread or member for this topic let me know.

a couple of you have mentioned brake drag. i had the front drivers wheel jacked off the ground and it didn't spin freely. it didn't take a lot of effort, but i think the brake was engaged very slightly. the PO installed new front brakes shortly before he sold it. the front brakes are producing a lot of brake dust. how can i tell if the drag is normal? should the wheel spin completely free? like not stop the instant i quit turning it?

check them AFTER you've driven around awhile.. and still hot. I've seen cold brakes spin perfectly, but soon as you put some miles on.. hit the brakes a couple times... which makes them hot, which will make them tighter, more heat, tighter.. see a pattern here? lol.
A normal 'hot' disk should only have a slight drag. Fairly easy to turn by hand, but definitely will not keep spinning afterward

Later!

......New to me: 2006 Lib, crd. Taking possession next week!!! I hate this forum! I REALLY WANT MY JEEP!!! :BANANA:

mass-hole · **Posted:** Sat Sep 06, 2014 4:01 pm

The gde tune offer so much more than just a few mpgs. You eliminate egr, you have a much smoother engine, and you get the increase in power.

You could save a few bucks by mailing gde the ecu like I did. It got there and back in 4 days and cost me like $15.

Also I don't believe that the tune files on these jeeps are vin specific, only year and region specific. People who are writing their own tunes here are able to give them to other people without issue. However, the gde programmer is vin specific so your plan is still not going to work.

npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

You got it tuned for $15? Or was that the potage? If it was just the postage, what did the tune cost? Was it the full $500?

I totally get what you guys are saying about the tune having more benefits than just fuel mileage. But odds are that two years from now I will be wanting something different to drive and the mileage savings by then will be minimal. The longevity it adds to the engine will benefit the next owner way more than me. Just sayin...

I'm going to dig into the "DIY" tune mentioned earlier. Sounds like a lot of fun. There's no tellin what I can mess up....

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WWDiesel · **Posted:** Sat Sep 06, 2014 10:56 pm

The DIY tunes listed on Squeeto’s tread eliminates all the DTC's caused by unplugging and removal of the EGR and FCV components. The tunes are year model and version specific as outlined in the thread. The EGR/FCV delete flash also allows you to run with MAF connected and no DTC....

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=98&t=78418

npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

Just got the paperwork from the PO. Looks like the F37 recall has been performed. Says the torque converter was replaced and the tcm programmed. Does this mean I have the updated torque converter? Or did they just replace it with the same one, just a new one? I have read the f37 tune reduced power, did it also reduce fuel mileage?

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npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

The F37 install date was 1/5/2007. So it looks like I have the weak converter

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CATCRD · **Posted:** Sun Sep 07, 2014 11:57 pm

The optimum speed for mpg is as slow as you can go in top gear with these KJs. They are just not aerodynamic.

mass-hole · **Posted:** Mon Sep 08, 2014 9:41 am

npkdm wrote:

The F37 install date was 1/5/2007. So it looks like I have the weak converter

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I think you probably have the updated one, but not the Euro one. I dont think the Euro TC was available in the United States until much later. That said, I am running a GDE hot tune on mine and as far as i know the converter is the updated unit and it hasnt shuddered.

$15 was for the shipping there and back. $500 for the tune itself. Do you do any towing? Thats where the GDE tune seems to shine. The motor can clearly out-tow what the chassis is capable of now.

npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

I don't tow anything. The only reasons I have a liberty over a tdi jetta are 4x4 is nice in the winter, the liberty is a better off pavement rig, and I prefer to ride high off the ground. Cars feel like go carts to me. The liberty also offers the possibility of towing a small boat or camper, not that I am in the market right now.

I bought the rig purely for fuel mileage. I drove a gas guzzling full size truck before. My monthly gas bill was sickening. I found myself limiting how far from home I could go on pleasure trips based on fuel cost. The liberty has liberated me from that. I live in a small town and I have to drive at least 60 miles to do anything.

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rancherman · **Posted:** Wed Sep 10, 2014 11:18 pm

npkdm wrote:

I don't tow anything. The only reasons I have a liberty over a tdi jetta are 4x4 is nice in the winter, the liberty is a better off pavement rig, and I prefer to ride high off the ground. Cars feel like go carts to me. The liberty also offers the possibility of towing a small boat or camper, not that I am in the market right now.

I bought the rig purely for fuel mileage. I drove a gas guzzling full size truck before. My monthly gas bill was sickening. I found myself limiting how far from home I could go on pleasure trips based on fuel cost. The liberty has liberated me from that. I live in a small town and I have to drive at least 60 miles to do anything.

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Same here! I needed space when I piled the fam in.. my 94 Toyota pickup regular cab just wasn't too fun when 3 side by side were headed to town... 30 miles away! Cops frown when someone has to ride in the back... soooo I've been 'Liberated' too!
Plus, when we need to bomb across the open range, It'll be just fine
Flying down to snag the Lib next week. I decided to save airfare and fly in on Wednesday.... I couldn't make myself buy a ticket for tomorrow.. 9-11, still a little creepy. Wife thinks these mid 2000's are the best looking of all suv's! LOL< whatever makes her happy right??

dirtmover · **Posted:** Thu Sep 11, 2014 8:06 am

npkdm wrote:

The only reasons I have a liberty over a tdi jetta are 4x4 is nice in the winter

The winter benefits come at a price.

You'll find that winter has the biggest impact on mpg. I go from a peak of 28mpg in July/August right down to 22mpg in January. Before the GDE tune I was only getting 19mpg in the winter.

Auberon · **Posted:** Thu Sep 11, 2014 11:04 am

It's curious that no-one has mentioned maintaining / selecting shockers and possibly using tunable ones if you travel over many and varied road surfaces. A tyre that is kept as stable as possible in relation to the tarmac contributes hugely to economy by limiting vehicle jounce, bounce and wheel hopping - stabilising the little brick quickly. A seemingly forgotten factor and very much related to speed of travel / mpg.

npkdm · **Joined:** Wed Sep 03, 2014 8:28 pm **Posts:** 163

dirtmover wrote:

npkdm wrote:

The only reasons I have a liberty over a tdi jetta are 4x4 is nice in the winter

The winter benefits come at a price.

You'll find that winter has the biggest impact on mpg. I go from a peak of 28mpg in July/August right down to 22mpg in January. Before the GDE tune I was only getting 19mpg in the winter.

i am quite a ways south of you. i have had diesel pickups in the past and didn't notice a drop in mileage in winter. the average winter temp here is 33 degrees. it has been lower but usually for short periods in a particularly hard winter. most people don't run anti gel in their fuel and i have only seen a diesel gel one time. im pretty sure we don't even have a winter mix fuel here, i have never heard it mentioned. i am hoping i won't notice a difference.

Optimum speed for mpg and other advice wanted

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