What is "AUTO" mode really, vs. the 2WD and 4x4???

The Gas and Diesel Engines - VQ40De, VK56DE, YD25DDTi, V9X, Transmission, Transfer Case, Oil, Differentials, Axles, Exhaust...

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What do you leave your transfer case set to every day?

2WD always
106
75%
AUTO always
24
17%
4H always, I'm hard core.
1
1%
I wish I had a choice :-(
10
7%
 
Total votes: 141

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smj999smj
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Postby smj999smj » Thu Apr 18, 2013 7:39 pm

I've went from running it in 2WD mode to running it in AUTO mode all the time for the past several months, at least. I haven't noticed any change in MPG.


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disallow
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Postby disallow » Fri Apr 19, 2013 6:01 am

yeah i wish i had auto mode... dang.

EdithHotaling
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Postby EdithHotaling » Tue May 14, 2013 7:39 pm

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Marysville Rekey

ColinK
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Postby ColinK » Sun Nov 24, 2013 10:03 am

How does this sophisticated gearbox/ transfer box help if the front or rear wheels do not have lockers, ie. any two wheel (at times even one wheel) can spin by itself?
I tried my 2002 Toyota with standard transfer box versus my Pathfinder 2007 with full auto box on a particular slippery slope, both started slipping at almost the exact same spot, even the same wheels were spinning, this was Toyota in low range and Pathfinder in 4L (Low range), neither have any type of diff lockers.

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smj999smj
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Postby smj999smj » Thu Nov 28, 2013 9:56 pm

The Nissan uses an electronic limited slip, which basically means it uses the ABS/TCS system to create a limited-slip diff affect in lieu of a mechanical LSD.

ColinK
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Postby ColinK » Fri Nov 29, 2013 1:24 am

Sure, however that is only the centre diff, front and rear can still slip

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smj999smj
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Postby smj999smj » Fri Nov 29, 2013 4:05 pm

No, it's a brake-biased electronic limited slip system. It uses the ABS system to apply the brakes on the slipping wheel.

Heisenberg
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Postby Heisenberg » Fri Nov 29, 2013 5:33 pm

And it seems to work stunningly well in my experience :shock:

H

ablincom
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Postby ablincom » Fri Dec 06, 2013 10:16 am

I pick I wish I had a choice, cos I don't even know the function of most of the bottom. Great enlightment from you guys.

Willapps
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So.. Tell me about how 4lo "feels"

Postby Willapps » Thu Jan 02, 2014 3:19 pm

Because I have never used it outside of a parking lot.. But It seemed to be pretty weird feeling, it feels like the brakes are on until you apply enough power to overcome the brakes, then it almost"takes off" kinda jerkily.
I look forward to trying it for real at some point, but really wanted to know if this sounds like it is working as it should! Dash lights are operating as per the manual, I guess it could be just the issue of tyres not being able to slip on a paved surface, but it just feels like maybe the front of the car is pulling at a different rate than the rear?
Any feedback as to what yours feels like would be welcomed.
It's a Spanish built r51 2.5d, fully specced all singing all dancing transfer box, but on a manual 6spd gearbox, what you would call "stick shift" I believe ;)

Will.

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DreamerzCC
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Postby DreamerzCC » Wed Jan 08, 2014 1:52 pm

Great information, thanks

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patomwazi
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Postby patomwazi » Sat Mar 22, 2014 3:30 am

smj999smj wrote:The Nissan uses an electronic limited slip, which basically means it uses the ABS/TCS system to create a limited-slip diff affect in lieu of a mechanical LSD.
SMJ....is this system in all R51 pathfinders??...i have an 08' V6 and as i understand it has open diffs ie no LSD and/or mech locking....but what i have noticed when two wheels at opposite ends loose traction...even at 4LO....no kind of locking seems to happen or as i understand, brakes locking the affected/offending wheel and letting power to go to the other wheel...below is one example of two wheels at opposite ends lost traction and they just kept spinning like circus plates even with foot off the gas...

Image

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smj999smj
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Postby smj999smj » Sat Mar 22, 2014 10:57 pm

I'm pretty sure it's on all North American made R51's. Outside North America, I'm not sure.

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labsy
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Postby labsy » Sun Nov 02, 2014 9:49 am

patomwazi wrote:...i have an 08' V6 and as i understand it has open diffs ie no LSD and/or mech locking....but what i have noticed when two wheels at opposite ends loose traction...even at 4LO....no kind of locking seems to happen or as i understand, brakes locking the affected/offending wheel and letting power to go to the other wheel...below is one example of two wheels at opposite ends lost traction and they just kept spinning like circus plates even with foot off the gas...
Well, AFAIK there must be some constant sleep/wheel spinning present for "electronic locker" to kick in. Below predefined speed (I think it is 8 km/h...could be wrong!) VDC aka electronic locker does not play a role, because wheel turning speed does not differ enough. Remember, when turning at full the inner wheels have quite a different speed as outer wheels, because outer wheel curve is larger than inner circle.
So, above that minimum speed (which I am not sure exactly which it is), VDC will try to transfer torque from the wheels with less traction to those with more traction, and this applies to all wheels. The mechanisms used are:
- applying BRAKES at variable pressure to the spinning wheel(s)
- reducing engine POWER to achieve optimum torque distribution
But it will NOT in any case ADD power to your engine!

So, when your wheel(s) are in a situation described and pictured above, you will NOT get out by idling or by not applying enough gas, because you are out of parameters for VDC+ABS+all electronics to provide power to wheels with most traction.
Obeying laws of pure physics, the sum of torque on all wheels with traction must be greater than the torque needed to start you moving. PLUS there's addional power needed to create difference in wheel slippage for the electronics to DETECT what's going on, so you must give it a constant push on gas just above that sum.
On the other hand, if you push it too much, system wiil try to acomodate and even cut the power excess, but this would mean you are over the upper rescue point, which is again not optimal.

So, to sum it up:
1.) When wheels are spinning in AUTO, 4Hi or 4Lo mode, do NOT idle it and do NOT engage power by pulses; instead, give it a gas slowly, more and more, until you feel it grabs a bit more. If you let gas down at that moment, you need to start it over again, because you just told your VDS it is NOT a good traction. You need to give it few seconds to discover all possible combinations and it will get you out.
2.) Other general rules apply, like inertia helps a lot, also do not change tracks while trying the same muddy spot again and again, but rather build up your way through by repeatedly going the same track again and again.

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smj999smj
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Postby smj999smj » Sun Nov 02, 2014 11:29 am

Electronic LSD is different from an electronic locker. Electronic locker will do just that: lock the differential so that both wheels will turn together. I'm not sure about the SE-OR, but the other Pathfinder models only have electronic LSD, which only applies the brake on the free spinning wheel so the power goes to the wheel with the traction, but it doesn't have the ability to allow both wheels to be powered because it is, after all, an open-carrier.


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