Fuel Economy 2WD or Full Time 4X4 Difference?

logiclee · **Posted:** Wed Feb 27, 2008 12:28 pm

Hi All,

I've been doing a few trials the last couple of months and in my mixed driving I can't really see any economy gain by using 2WD.

Probably would be more noticable on a motorway/highway run at a steady high speed perhaps.

Anyone else measured a difference? I wouldn't have thought it would be to big a difference with the KJ not having free wheel hubs so the front half shafts, diff and front prop are still driven in 2WD mode.

Cheers
Lee

XJMA · **Posted:** Wed Feb 27, 2008 3:49 pm

Not a huge difference, but on the highway, I'd keep it in 2.

chadhargis · **Posted:** Wed Feb 27, 2008 6:03 pm

I keep mine in 2WD just to save the wear on the components in the system. I only use FT4WD if the roads are slick. Use PT4WD on loose surfaces (offroad).

n3qik · **Posted:** Wed Feb 27, 2008 8:26 pm

I am seeing a 2-4 MPG loss by driving in 4WD.

This is due to my very heavy foot. Very hard to lay rubber in 4wd and I like it that way as I have some bad intersections that I must pull out from everyday.

Bill.Barg · **Posted:** Wed Feb 27, 2008 10:19 pm

n3qik....

With ESP it is better to be in Full Time. ESP dont let ya burn rubber... so the best acceleration on corners is with 4wd for sure.

I have noticed a 1 mpg mileage loss with Full vs 2wd .

Reflex · **Joined:** Mon Jan 29, 2007 8:48 pm **Posts:** 567

I haven't noticed a loss but I'm sure its there. That said, I really do prefer how it feels to drive it in FT, but I only do so when its rainy/slick.

geordi · **Posted:** Wed Feb 27, 2008 11:23 pm

He has an 05, so there is a good chance he doesn't have the ESP system.

I will say, I don't think I've seen much of a loss in full time 4wd, but I also haven't left it there very long. Most of the time I'm in 2wd, but I have been noticing what feels like reduced traction lately from the rear end, not a mechanical thing, but that the tires are physically not grabbing as much road as they had been.

It might have something to do with the "Low country" area of Savannah / South Carolina being made up of about 90% MUD recently.

I am really getting tired of stepping in what looks like normal grass, to sink into a 3-4" deep puddle of quickmud. That, and getting my motorcycle stuck forward-in to a ditch that wasn't there before tonight... And having to use my KJ to pull out yet ANOTHER vehicle stuck sideways in the mud - MINE. Grrrrrr I'm SO over mud. Paving (or the dry season) can begin anytime now.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

What would really be interesting is if someone put hubs that unlocked on the front. It would be nice to see how many more MPG you get when not turning the front CVs/driveshaft/diff.

Sir Sam · **Posted:** Thu Feb 28, 2008 3:51 am

Pablo wrote:

What would really be interesting is if someone put hubs that unlocked on the front. It would be nice to see how many more MPG you get when not turning the front CVs/driveshaft/diff.

You sound like every XJ driver since 1984.

I'm still waiting.

Uffe · **Posted:** Thu Feb 28, 2008 4:05 am

chadhargis wrote:

I keep mine in 2WD just to save the wear on the components in the system. I only use FT4WD if the roads are slick. Use PT4WD on loose surfaces (offroad).

There will always be a bit of wear on the components since we can't unhook the wheels from the driveline. Still the forces are less when you have it in 2wd because you only turn the shafts around.

I use FT when it's slick, but with the new Cooper tyres I haven't had much use for FT because they grip better than the old worn Goodyears. That could be because the tyres are new and not as worn or because the tread is different. I will find out in a year or two

logiclee · **Posted:** Thu Feb 28, 2008 11:03 am

Uffe wrote:

chadhargis wrote:

I keep mine in 2WD just to save the wear on the components in the system. I only use FT4WD if the roads are slick. Use PT4WD on loose surfaces (offroad).

There will always be a bit of wear on the components since we can't unhook the wheels from the driveline. Still the forces are less when you have it in 2wd because you only turn the shafts around.

I suppose you could say using FT evens out the wear more evenly as it takes load off the rear diff, and prop.

I use FT when Towing both for the traction and to distribute the torque between front and rear.

Cheers
Lee

jinstall · **Posted:** Thu Feb 28, 2008 1:41 pm

I used the FT4wd in the rain once getting down th eautobahn at about 90-110mph, I noticed a huge difference. I normally never use it only 4wdhi and 4wdlo

Uffe · **Posted:** Thu Feb 28, 2008 2:40 pm

logiclee wrote:

I suppose you could say using FT evens out the wear more evenly as it takes load off the rear diff, and prop.

I use FT when Towing both for the traction and to distribute the torque between front and rear.

Cheers
Lee

Funny that you mention it - this is what I do too ...

n3qik · **Posted:** Thu Feb 28, 2008 7:16 pm

Bill.Barg wrote:

n3qik....

With ESP it is better to be in Full Time. ESP dont let ya burn rubber... so the best acceleration on corners is with 4wd for sure.

I have noticed a 1 mpg mileage loss with Full vs 2wd .

05 did not have ESP.

Quick update: just had the F37 recall done. EVIC is showing a gain of 1.5 MPG better. But will know better when I fill up in a day or so.

geordi · **Posted:** Thu Feb 28, 2008 8:40 pm

Did they flash your computer too, or just do the converter and pump?

n3qik · **Posted:** Fri Feb 29, 2008 7:36 pm

Flashed twice, failed both times. New PCM :cry:

Power/running wise not happy with new programing. Going to fill up tomorrow @ $3.78/gal. HOLY stinky poo was $3.45 two weeks ago.

geordi · **Posted:** Sat Mar 01, 2008 12:43 am

I wish you had told them to NOT screw with your TCM and ECM... Now you have a crippled car like the rest of us, and nobody can read the stock flash to maybe save it and re-flash (un-neuter) the rest of us.

I'm probably going to be getting a Suncoast eventually, depending on if I kill the stock TC before the warranty is up. One thing I'm looking at first however, is the InMotion tune or maybe a plug-in module that will bump the mileages...

Of the plug-in modules, which one offers the best bump in MPG, provided you can keep your foot off the loud pedal?

In other news, I'm thinking that my exhaust system might be getting a little "looser" this next week... I have a sawzall, and the availability of straightpipe to clamp into place... :twisted:

Fuel Economy 2WD or Full Time 4X4 Difference?

Who is online