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2013 Sorento, Suzuki V-Strom
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Discussion Starter #1 (Edited)
New Sorento owner here. The car has AWD with the locking center differential. I know how I expect it to work,* but the owner's manual (pg 5-22) only lists the 4WD, not AWD...usually two different things, but in this case, who knows?

The owner's manual says that the 4WD is normally 2WD (FWD, I think) but it will switch itself to 4WD when it wants to (detect front wheels slipping?). There is a manual 4WD activation button, but that disconnects the locked 4WD automatically between 19 to 25 mph, switching to auto-4WD.

Is the AWD different? And which end of the AWD car gets the tire chains?

The poorly trained phone rep at Kia Customer (non)Assistance had no more info than to read the owner's manual along with me, and he got a bit huffy when I asked if he had access to an engineer or anyone to really knew how AWD worked. He said to ask a dealership parts-changer...errr...technician.

Anyone out there know for sure how AWD works?


*I expect the AWD to drive all four wheels with the center differential allowing different front & rear axle speeds on firm surfaces. When on slippery surfaces the center diff can be locked for more traction under some circumstances, but the car must not be used on firm (good traction) surfaces if the center diff is locked. Without a limited slip or locking axle differential, and the unlocked center differential, it could result in only one tire spinning and the car going nowhere. With the center diff locked, power goes to both front and rear, so one tire at each end could be spinning and the car go nowhere, a bit better option. Anyway, that's my assumption, but I don't know if Kia shares this assumption.
 

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2013 Sorento EX V6 AWD
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Timely topic ... We just purchased a 2013 Sorento V6 AWD, and I'm still digging into how it actually works.

I'm going to repeat some of your post because this is clipped from another forum in which I participate ...

It's important to understand exactly what you get with the Sorento (or alternative) "AWD." From the Sorento "Owner's Manual" ...

[Note that the manual uses "4WD" in a somewhat idiosyncratic way. See the link at the end of this post for an explanation of the terms.]

"4WD Auto (4WD LOCK is deactivated) ... Vehicle operates similar to conventional 2WD under normal operating conditions. However, if the system determines that there is a need for 4WD mode, the engine's driving power is distributed to all four wheels automatically without driver intervention."

"4WD LOCK ... This mode automatically begins to deactivate at speeds above 19 mph and is shifted to 4WD AUTO mode at speed above 25 mph."

So ... "locking center differential" is a bit of a misnomer, since (according to this description) the center differential is fully "locked" only below 20 mph.

In any case, when the center differential is not locked, if any one wheel is slipping, all the power would normally be sent to the slipping wheel, and you would be stuck. However, according to Kia, "The advanced Traction Control System (TCS) can sense wheel spin during acceleration. When it does, it uses a combination of engine power and brake force to transfer power to the wheels that have the most traction, providing both increased control and enhanced responsiveness."

Now, when the center differential is actually locked, power is always sent to both front and rear axles. Thus, even without TCS, if either axle has both wheels getting traction, then those wheels can pull/push the vehicle even though the other axle has one or both wheels spinning (and therefore isn't providing any push or pull).

Leaving TCS aside, with the center differential locked, if at least one wheel on each axle is slipping, you're still stuck. TCS attempts to mitigate this problem by applying braking force to each slipping wheel so some power still gets transferred to a wheel with traction.

How well the combination of "locking center differential" and TCS will all work in practice can only be determined by experience. However, the ability to lock the center differential when you're trying to get going on snow or ice (or mud) should provide an advantage over a center differential that can't be locked.

It's not at all clear the maner in which "AWD auto" mode and/or TCS transfers power to the rear axle. For example, is it incremental or an on/off function? And at low speeds, is the center differential truly "locked" and is the power distribution between axles 5/50?

Since I drive a conventional 4x4 truck (with 2WD and 4WD and no center differential), the Sorento approach to a "locked center differential" seemed odd at first. But upon more thought, I can see a rationale behind disengaging the "locked center differential" above 25 mph. Once you're rolling at that speed, you shouldn't have any wheel getting all the power because it has no traction while the other wheels do; at least not for long. So, a more dynamic adjustment of power between the axles could be adequate and save wear-and-tear. Nevertheless, I would rather have the ability to keep the differential locked; as with my 4x4 when I roll along straight, paved, packed-snow Forest Service roads (when there's no traffic) faster than 25+ and want constant power to both axles for stability.

I'd really like to have a more complete, technical explanation of how the Sorento implements AWD, "locking center differential" and TCS. Once I'm registsered on kia.com, I hope to get access to the service manuals.

Here is a technical Comparsion of AWD and 4WD systems
 

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2011 Sorento V6 AWD
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You should have done a quick search as some members have taken the time to explain it in great detail.
 

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2013 Sorento EX V6 AWD
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I did do a search, but must have missed it. Could you help both of us "newbies" by providing the link?

Thanks.
 

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2013 Sorento EX V6 AWD
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Digging through myriad threads of marginal value, I found two that were helpful:

A very thorough technical discussion that appears to be well-informed:
2011 Sorento AWD explained

Another thread that adds a little bit:
Question about AWD

Both are dated, and there may (or may not) have been important changes two model years later.

What I'm still looking for is the AWD, ECS, TCS, ABS and "4WD lock" control logic used in the 2013 V6 AWD.

For example, there is no explanation for this ambiguous statement in the manual:
"4WD LOCK ... This mode automatically begins to deactivate at speeds above 19 mph and is shifted to 4WD AUTO mode at speed above 25 mph."​
What happens from the point the mode "begins" to deactivate until it is completely switched to 4WD Auto?
 

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2017 Sorento LX
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I came from an 06 (2WD/4wd Hi/Lo) to a 2011 (AWD). I wasn't sure what the difference was either. What I have found out in the past week and a half since we got our snow storm solved my dilemna. When I go up my street from my driveway, it is uphill. My 2 front tires will start to spin ( cause they have forgotten how to plow apparently) and in about maybe 5 seconds, I will feel the back wheels kick in, and the power going to all 4 wheels stop the spinning, and I get traction. When I am on the job (delivering papers at 2 in the morning) and I have a tough uphill drive, or a mountain of snow left from the plows, and can't get up, I lock in the differential. I find it works pretty much like 4 WD high, and gives me the power to go up and over...Not sure if that answers your question, but that's the (very) simple version...don't know about chains, because I don't use them
 

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In short:

The Sorento is FWD. It has no "actual" center differential. It has a clutch pack than can either be engaged or not be engaged. When the clutches are engaged the front and rear axles are linked just as in a 4WD truck. The axles will spin at the same speed. Both the front and rear differentials are open so there is no ability to transfer torque across an axle other than via the traction control system.

The neat thing about the clutchpack, is that it can be engaged and disengaged very quickly, thus functioning in a similar fashion to a true LSD. If the clutch packs are engaged for 30% of each second, then 30% of available torque is sent to the rear (which would be 15% of torque from the transmission, assuming the front axle has traction).

Does that make sense to you?
 

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The other advantage of AWD is that it's usually FWD which saves gas. In 4wd there is more drag so you get worse gas mileage.
 

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2013 Sorento EX V6 AWD
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Info from service manuals re 4WD transfer

Well, I finally overcame a technical glitch on www.kiatechinfo.com and could peruse the 4WD section of the 2013 Sorento V6 (G 3.5 MPI) Service Manual.

The vehicle uses a transfer case, rather than a center differential. They call it the "Intelligent Torque controlled Coupling (ITCC)". It uses an Electric Magnetic Clutch (EMC) to "Control the slip of inner & outer plate. Control variably the driving force distribution to optimize front & rear driving force." (The manual also states: "Distribute the required driving force after 4WD ECU operates.")

The EMC is controlled by logic in the ECU (I assume "Electronic Control Unit"), based on the following inputs:
"A. Input torque (Throttle position sensor)
B. Cornering situation (Steering angle sensor)
C. Vehicle speed and different wheel speed front & rear (Wheel speed sensor)
D. Braking situation (Brake signal and ABS signal)"

So, the ITCC is capable of variable (rather than constant or "pulsed") transfer of torque, based on the factors listed above.

What I'd like to know now is the basic logic for the control, particularly whether or not the 4WD actually uses the ITCC's variable capability.
 

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Well, I finally overcame a technical glitch on www.kiatechinfo.com and could peruse the 4WD section of the 2013 Sorento V6 (G 3.5 MPI) Service Manual.

The vehicle uses a transfer case, rather than a center differential. They call it the "Intelligent Torque controlled Coupling (ITCC)". It uses an Electric Magnetic Clutch (EMC) to "Control the slip of inner & outer plate. Control variably the driving force distribution to optimize front & rear driving force." (The manual also states: "Distribute the required driving force after 4WD ECU operates.")

The EMC is controlled by logic in the ECU (I assume "Electronic Control Unit"), based on the following inputs:
"A. Input torque (Throttle position sensor)
B. Cornering situation (Steering angle sensor)
C. Vehicle speed and different wheel speed front & rear (Wheel speed sensor)
D. Braking situation (Brake signal and ABS signal)"

So, the ITCC is capable of variable (rather than constant or "pulsed") transfer of torque, based on the factors listed above.

What I'd like to know now is the basic logic for the control, particularly whether or not the 4WD actually uses the ITCC's variable capability.
I don't think that the coupling unit can apply differing amounts of torque. It either activates the solenoid or does not. That is typically how solenoids work, and if it purposefully slipped the clutch plates within the coupling unit the friction material would be dead within a few thousand miles. That would cost Kia a fortune with their 100K mile warranty.
 

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I understand what you're saying, which is why my final question. However, the Service Manual is quite explicit about "variably" and "control[ling[ the slip."

Would be nice if could get an answer from a knowledgeable Kia engineer.
 

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I understand what you're saying, which is why my final question. However, the Service Manual is quite explicit about "variably" and "control[ling[ the slip."

Would be nice if could get an answer from a knowledgeable Kia engineer.
I agree, I would really like to take one apart to play with and see how it works. Anyone want to volunteer their sorento for me? I think that those terms are stretching the truth, and that the system is controlled via pulse modulation over time. That "effectively" controls slip. That is for sure how most of the other systems out there like this one work. I can't be certain about this one though. What I am quite confident about is that the logic that controls it really shuts it down big time when the wheels are turned. It really aggravates me when I am turning up a hill from a stop when its wet out. That is the one and only time I get wheel spin.
 

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An example of why I'd like to know for certain ... if operation of 4WD LOCK between 20 and 25 mph does let the clutch plates slip, it might be advisable to minimize the time driving within that speed range when in 4WD LOCK.

RE: "it really shuts it down big time when the wheels are turned"

Tell me I've misunderstood! Do you mean in 4WD LOCK, going 15 mph on ice and I steer around a sharp curve in the road, the "Intelligent" TCC is going to disengage the clutch and quit transferring power to the rear axle?
 

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Discussion Starter #14 (Edited)
Interesting stuff. So the electric coupling can vary the proportion of power sent to the rear axle.

I'll miss the secure feeling of driving down a steep snowy hill in 4wd with engine braking effecting all four wheels. The fronts-only for engine braking isn't as secure. And I now know that tire chains must be on the fronts. If the driveshaft coupling locks below 19 mph, why does the Kia video recommend using it for descending sharp curves at slow speed on dry pavement? I'd never run 4WD without a center differential in that condition.

My window sticker says that my car has "All Wheel Drive w/Locking Center Differential." I guess the actual drive train description can be stretched to call it All Wheel Drive (although I wouldn't call it that), and it is a lie about the center differential.

The other advantage of AWD is that it's usually FWD which saves gas. In 4wd there is more drag so you get worse gas mileage.
We have to be careful of terminology here. Usually AWD means that all wheels are always driven but there is a center differential or other device that lets the front and rear axles turn at different speeds. 4WD usually means that there is no such device and the vehicle must not be driving on a firm surface when 4WD is engaged. And with vehicles such as my 4WD truck, the amount of parasitic drag by extra turning parts depends on where the drive disconnects are located, in the case of my truck at both the transfer case and the front differential.

By the way, I tried to search for the AWD info, but I got nothing as a search result. It might be due to a popup blocker or other conflict with the Firefox browser I'm running...I have more checking to do. And, I'm waiting for Kia to get my VIN into the system so I can access the tech info and service manual.
 

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There is no mechanical reason why the AWD setup in the Sorento will save fuel over a vehicle with a true center differential. The *only* difference between the two is that you may get a modicum of additional friction with a center differential that is always turning, vs a modicum less with the sorento whose clutches are not always engaged. Every single other part of the drivetrain is always turning, and the added weight is always there. The whole "FWD is more fuel efficient business" is just a marketing ploy used because these cars are not true "AWD" in the purest sense of the term. They are really more like an "automatic 4WD" if you could turn your 4WD on and off really really fast a few times a second. It does the job, and I like it fine, but its not the type of setup people would imagine when they see youtube videos of rally racing and such.
 

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My wife had a 1988 Toyota Camry Alltrac 5-speed manual, which was true AWD with a locking differential. I ran four studded winter tires on it, and it was absolutely terrific in ice and snow, accelerating, braking and handling.

She replaced the Alltrac with a 1999 Infiniti I30, which has been a sweet highway car, but no snow vehicle. So, I drive a 2008 Nissan Frontier V6 4x4 and it serves when we head into the Cascades in snow.

So ... her choice of a Sorento V6 AWD to replace the "I" was to sit higher and have a "nice" car for winter mountain trips. That's why I want to know how the Sorento AWD really works.

I plan to put Michelin X-Ice Xi3 tires on the Sorento when (and if) they become available for winter 2013-14.

My "backup" for this year and to keep stowed on-board for extreme conditions in future years is a pair of Thule XG-12 Pro self-tightening chains.

* * * * *

BTW, do any of the "old hands" who are reading this thread know how to get a technical answer from a knowledgeable Kia engineer? Seems kind of inefficient to be spending a lot of time speculating when someone in Kia certainly knows exactly how the AWD works.
 

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My wife had a 1988 Toyota Camry Alltrac 5-speed manual, which was true AWD with a locking differential. I ran four studded winter tires on it, and it was absolutely terrific in ice and snow, accelerating, braking and handling.

She replaced the Alltrac with a 1999 Infiniti I30, which has been a sweet highway car, but no snow vehicle. So, I drive a 2008 Nissan Frontier V6 4x4 and it serves when we head into the Cascades in snow.

So ... her choice of a Sorento V6 AWD to replace the "I" was to sit higher and have a "nice" car for winter mountain trips. That's why I want to know how the Sorento AWD really works.

I plan to put Michelin X-Ice Xi3 tires on the Sorento when (and if) they become available for winter 2013-14.

My "backup" for this year and to keep stowed on-board for extreme conditions in future years is a pair of Thule XG-12 Pro self-tightening chains.

* * * * *

BTW, do any of the "old hands" who are reading this thread know how to get a technical answer from a knowledgeable Kia engineer? Seems kind of inefficient to be spending a lot of time speculating when someone in Kia certainly knows exactly how the AWD works.
I have attempted contacting their customer service but those people are useless. My advice would be to write to borg warner since the Sorento uses the Borg Warner iTM3e system. I have been meaning to do that for more than a year and never have.

The Sorento should be considerably better at the margins in the snow than your Frontier. FWD based, less weight, ind. rear suspension, and no need to keep it locked and cause axle hop. That said I love Frontiers. I'm looking to pick a used one up on the cheap and bring its maintenance up to date to have as a hunting/project truck. Sorento with a hitch carrier / utility trailer works. But I really miss having a truck.
 

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Discussion Starter #18
I plan to put Michelin X-Ice Xi3 tires on the Sorento
If you also live on the we(s)t side of the Cascades, consider the Hankook i*cept evo tires. Consumer Reports rated them better for wet braking than the Xi3, not quite as good in snow.


Here is an interesting vid of the Sorento in Russian snow:
dunn'o what tires he has, maybe Nokian. Certainly not Kumho Solus. Anyway, the drive system is working well for him...this says nothing about how the car will handle on a snow base road at 50 mph.
 

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Loved the video! ... Especially the part at the very end where the Sorento lifts its rear wheel as if to "mark" the road it's just dominated. :lol:

We live in Eugene -- on the we(s)t side. But our priority for tires is braking and handling when travelling on snowy/icy highways through the passes. :auto:
 

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I found an older, but perhaps relevant post on the iTM3e in the Hyndai forum.

It was posted by phatboyc on February 28, 2007. Click here for the original post.

I didn't find any product information (other than press releases) for the iTM3e on the Borg-Warner website.

* * * * * *

Here are two articles I found this summer while doing research on the 07 SantaFe AWD system. Very informative. I though it would be a nice addition to this forum.

"Hyundai's all-wheel drive system"

By Jim Kerr

Hyundai has just introduced the 2007 Santa Fe and one of the features available on this mid-size SUV is all-wheel drive. It is a new system for Hyundai and is a good example of how electronics are improving all aspects of driving.

All-wheel drive systems are confusing for many people. I must admit to wondering myself to what type of system is being described in the sales literature. Let's see if we can simplify it. All-wheel drive provides power to all the wheels, as opposed to front-wheel drive or rear-wheel drive systems that only provide power to one end of the vehicle. That's clear enough, but some systems are also called four-wheel drive. Those systems also drive all the wheels, but are not designed to operate in 4wd mode all the time. The driver has to select 4wd when traction conditions are poor. But operate in 4wd mode on hard pavement and you will soon be paying for expensive driveline repairs.

Click here to find out more!
All-wheel drive however, can be operated on hard road surfaces. Some systems drive all the wheels all the time. A viscous coupling or a variable clutch inside the transfer case controls the rate of slip between the front and rear axles. Subaru and Audi are examples of great all-wheel-drive vehicles that use these controls.

Many of the compact and mid-size SUVs such as the 2007 Santa Fe use a front-wheel drive system with an auxiliary rear-wheel drive to provide all-wheel drive. This is better than it sounds. Modern control systems allow the vehicle to operate with front-drive only for most driving to optimize fuel economy, but engage the rear-wheel drive as soon as additional traction is needed.

Hyundai's new system uses a computer-controlled clutch mechanism mounted in front of the rear axle to engage the drive. It is a Borg Warner system that can provide up to 99% of the torque to the front wheels, but automatically diverts up to 50% of the torque to the rear wheels when needed. The driver can push a button on the dash as an input to the computer, commanding it to "lock" the torque transfer at 50/50 for getting out of slippery parking spots in winter or ploughing through some soft sand. While there is no low range in the Santa Fe all-wheel drive system, it is more than capable of handling many off-road excursions.

Because the torque transfer to the rear wheels is variable, a dependable, durable clutch mechanism is needed that can be instantly engaged. To do this, the computer monitors wheel speed, accelerator pedal movement and steering inputs. When 4% or more front wheel slip is detected, the rear axle starts to engage. It can also anticipate the need for additional traction and engage the AWD system when the driver accelerates the vehicle. Another feature is it can disengage the rear axle during ABS events to optimize ABS stopping.

The computer controls a large solenoid coil in the clutch housing. When energized, the solenoid pushes against a multi-plate clutch, which in turn holds a washer-like plate from turning. Ramps and balls between this plate and a second plate cause the two plates to be forced apart, placing pressure on a second larger multi-plate clutch that connects the driveshaft to the rear axle. The path of torque is complete and the rear wheels drive.

A button on the dash can lock the clutch to provide 50% torque to the rear wheels, but this only occurs below 35 kph. Above that speed, the computer pulses the solenoid to disengage the clutch mechanism, but it will automatically engage it again when vehicle speed lowers.

Finally, the system monitors steering wheel angle. Turn the steering wheel, such as when parallel parking or turning a tight corner and the computer will decrease the torque applied to the rear wheels to there is no driveline binding during the turn.

Computer controls, electric solenoids and data communication between computers are all used to provide smooth traction regardless of the driving conditions and optimize fuel economy too. That's modern all-wheel drive."
Auto Tech: Hyundai's all-wheel drive system - Autos.ca

On the BorgWarner website I found this info.

" The BorgWarner High Energy ITM3e™ AWD System is the first industrialized all-wheel drive (AWD) coupling that combines a mechanical system, active gerotor pump, thermal management and new AWD control algorithms into a fully dynamic system that provides world-class performance in a package space only passive systems could achieve previously.

The ITM 3e™ is unlike any other active AWD product. The design features a third friction element, which provides maximum torque transfer in a package size optimized to allow installation in smaller passenger cars and crossover vehicles (CUVs). It also combines best-in-class drag torque performance, which improves fuel economy. The ITM 3e™ was recently launched in the Hyundai Santa Fe and in the Chery Tiggo produced in China. A new North American CUV program and a European high-performance application will begin production later this year.

The BorgWarner High Energy ITM3e™ AWD System and The BorgWarner Turbo & Emissions Systems Gasoline Turbocharger with Variable Turbine Geometry have been named finalists for the 2007 PACE Awards."

Guess who developed Acura's popular SH-AWD system? Thats right, BorgWarner.

I also read that the ITM 3e™ was also used and adapted to the 2006 and up Porche 911TT's!
 
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