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What type of 4x4 is Auto mode?

43K views 53 replies 25 participants last post by  Release 
#1 ·
#34 ·
I've done even more research, and I've discovered a number of companies have pulled off the trick of creating an AWD system without the center diff.
Check this link out:

http://www.autozine.org/technical_school/traction/tech_traction_4wd_21.htm

I was surprised to find out that the Skyline GT-R is without center diff as well. In fact, it uses a multi-plate clutch system to send power up front only in times of need. This results in an AWD car that acts RWD most of the time, and is free of the oversteer normally associated with center-diff based AWD systems.
 
#35 · (Edited)
Multiplate systems that slip the clutch...and as a result can only be partially engaged with slippage for a limited time.

Note, when the 959 was designed a fast computer had a 33Mhz 16-bit 486 processor with 640kb of main memory and 2-4Mb of LIM programmatically mapped memory. They may have had 100Mb of disc space.. They cost around $3000 in 1988 dollars, maybe around $5k today. For comparison I'm writing this on a quad core 32-bit computer at 3Ghz (4x processor, 2x the internal bandwith, 100x the processor speed) with 8GB of main memory (2,000-8,000 times as much depending on how your measure) and 5TB of disk space (50,000x as much).

As Mr. Spock said: "Stone knives and bear skins"
 
#36 · (Edited)
I'm going to throw in my .02 and if it comes off condescending and rude i apologize in advance because that is not my intention.

Mostly what im hearing on this thread is speculations, i highly recommend you guys go out and try the system out for yourself. When in auto mode the car starts off in 4wd everytime you come to a stop. The system is a lot quick than you and will save your @$$ before you even get yourself in trouble. Let me explain; there is this corner by my house and it is notoriously slipper and i can get my car sideways Japanese drifter style on the throttle in 2wd. I tried the same corner in auto and it automatically shifted the power to the front and it pulled me through the corner in the intended line with out slip, fuss or drama.

In auto the Transfer case isn't locked to a 50/50 torque split like in 4HI thus the reason why you can turn on dry pavement. I have been in every kind of mucky off road situation you can think of snow, ice, mud, rocks, dirt, gravel everything. When the truck is in auto you can feel the car 'throwing' the power around. The same cannot be said in 4HI, in 4HI you can feel the driveline being a tighter and the truck always wants to maintain a straight headway. Often times even in slippery situations you will not be able to turn very much in 4HI since the driveline is trying to maintain the same speed on both axles

Pops im sure your familiar with all of this but to those of you that arent i suggest you find an empty snowy parking lot or a muddy field. Dont underestimate this 4WD system it is very advanced. 9/10 times auto will save your @$$ or get you out of sticky situations.
 
#37 · (Edited)
So we got a lot of snow last night here in Utah. So I decided to see how well the Auto works. I stopped a stop sign and with the road covered in slon gunned it around the corner. It fished a tad and a light on the right side of the speedometer lit up for a quick second (not sure what it was? prob VDC?). But it did not appear to have the 4wd completely engaged from start because I felt it correct it self after it came on.

I can definitely feel when the 4HI is on as the drive train makes more noise. But with Auto it is hard to tell when the front axle is driven. What I can tell you is Auto works great. There were 3 cars that did a 360 last night in front of me and one GMC truck that went into the deep snow median. I never felt like I was even close to slipping. And that is with 20% left on the stock Conti tires. Can imagine how well it will do when I put Revos on it.
 
#38 ·
Try this : VDC off 2WD mash it to like 30-40

After Try this : VDC off Auto mash it to the same speed. You will be able to tell the difference.
 
#39 ·
I'm a newbie to the Armada and the forum...I am about to buy a used LE and was going to go with 4x2 until I read the 4WD threads...does anyone see signifcant MPG differences between the 2WD mode and Auto mode? Thank you all for your insight.
 
#41 ·
You where comparing 2wd MODE on a 4wd, not a 2wd.

The 2wd, with on less differential turning, less weight, etc. should do better. How much better? Probably only 1-2 mpg.

I doubt anyone has both and done a back to back test. Event then, the two would have to be the same model, as the features on the high end models add weight. On the QX56, EPA goes from 12/17 to 12/18.
 
#43 · (Edited)
You where comparing 2wd MODE on a 4wd, not a 2wd.

The 2wd, with on less differential turning, less weight, etc. should do better. How much better? Probably only 1-2 mpg.

I doubt anyone has both and done a back to back test. Event then, the two would have to be the same model, as the features on the high end models add weight. On the QX56, EPA goes from 12/17 to 12/18.
Actually, there's been alot of discussion, comparison, and a few Titan owners who have gotten together for comparison. Believe it or not, the 4x4 and 4x2 MPG are just about identical. Apparantly, our torque is more than enough to compensate for the weight and the transfer case + front diif and driveshaft really are pretty lightweight anyway. Altogether, they're only about the same weight as carrying another passenger and I haven't ever heard of anyone's mpg dropping when their brother is riding along. -lol :D

I would think that added drivetrain drag might make a difference, but I don't know that it's been evident yet.

The biggest mpg difference seems to come from the BT -vs- non-Tow gearing. The non-Tow guys are easily getting 17mpg daily.
 
#44 ·
The Titan comparison may be useful, but probably doesn't have the resolution to detect 1 MPG differences accurately.

It wouldn't be just the weight. The components are rotating (adding inertia, effectively more weight) and there is significant friction in the components. My wife, riding along, also adds 'friction', but it isn't quite the same.
 
#45 · (Edited)
aka: "drivetrain drag" ;) That's where you'll get into unlimited variables because it all highly depends on the fluids' viscosity and bearing packs', pinons', etc.. resistance rates at that particular time. And as we all know by now, no 2 bearing packs seem to be the same even when brand new and our pinions aren't exactly top notch quality. Gotta love today's so called "Quality Control". - lol :rolleyes:
 
#46 ·
the Nissan dealer ask me to keep 4WD shift switch on 2RW and He said, if I drive on AUTO mode on high speed, the gearbox will damage soon !!! that's TRUE ????
Beside, I like to travel on road and AWD or AUTO is on, I feel safe and car stability on curves
 
#49 ·
I read too, I believe either in the manual, or on the card that shows the functions of the 4wd system, that you can switch between 2wd and auto at any speed. That tells me it's not an issue at highway speeds.
 
#50 ·
You can. This is the same system that was on our old 01 Pathfinder and it was a "shift on the fly" deal where you could always shift from 2WD into Auto. We basically kept in Auto all the time so the truck did the "thinking" of when you needed 4WD. Since we put 129K (and I know who we sold the truck to) on it w/no issues, the whole dealer comment about wearing out the components is horsesh...well....you know!
 
#51 ·
thank you BlakSpyda & Pops, I have to slap him lol. when i receive my car, it was very rainy and he told me never drive in AUTO mode even in rainy weather, beside not allow to drive in AUTO mode more than 60Km/H, so i told him this option cost me $3000 (that a difference price between LE 4WD and LE 2RW only) so where can I use it ?
 
#52 ·
.... when i receive my car, it was very rainy and he told me never drive in AUTO mode even in rainy weather, beside not allow to drive in AUTO mode more than 60Km/H, so i told him this option cost me $3000 (that a difference price between LE 4WD and LE 2RW only) so where can I use it ?
Excellent question because I had one dealership refuse me Warranty Coverage because one of the excuses they said was "it's been driven Offroad".. So, I told them "Well duh, WTF else would've I have bought a 4x4 SUV instead of a 2wd Mini-Van? If you want to push a minivan pitch off onto somone, you picked the wrong sucker so fix it or someone else will." So needless to say, someone else did and won my future business. :rolleyes:
 
#54 ·
Which parts went bad for the AUTO 4wd

The 2004 Armada switch from 2wd to AUTO did not work and when switched, the 4WD light will come on solid.
Took it in for a check up , was told the signal to convert to the AUTO did not work. so the auto mode could not be engaged. Was also told the 4WD and the 4Lo were working fine.
Parts and labor comes to $1500 ( estimate ) for a new OEM part and the used part is $900 w labor.

Somehow the name of the parts needed is not transparent. Labor was high because the glove box has to be removed for access.

Anyone has experience with this issue ?

Thanks
 
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