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Unread 11-30-2014, 05:30 PM   #1
Karl1957
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Question about Jeep Compass 4x4 operation

Hello folks. Hopefully somebody here can address some concerns I have about a new Jeep.

First of all let me say I have been driving 4x4's all my life. I've had 2 Ford F150 4x4s, a Dodge Ram 4x4, a Ford Bronco 4x4 and an old Jeep CJ 4x4.

On every one of those vehicles you could absolutely tell when the 4 wheel drive was engaged. You could tell a difference in the road noise, the vibration, the feel in the steering wheel. You could feel the vehicle lurch when you went into a hard turn, you could feel it pull its way through the mud, gravel etc......

It's important to me to have a dependable 4x4 vehicle. I'd like to know that I can depend on it to get me to work and home safely when it snows, or if I find myself on icy or muddy situations.

I just recently traded off my old Ford Bronco for this new 2015 Jeep Compass and I specifically told the dealer I wanted 4 wheel drive. The owners manual says it's a 4x4, there's a yellow light on the dash that comes on and says 4x4, but I swear I can't tell a difference in the sound or feel of the vehicle. Is this normal? Or is my system just not working?

It doesn't seem to feel any different when I pull the "4 wheel lock" Lever. I don't hear any difference in the road noise. I don't feel any vibration underneath me. There is no "Lurch" when you go into a turn. It doesn't feel any different to me than it does when it's in standard "Unlocked" mode.

I'm not sure I can trust this thing in those situations where 4 wheel drive is needed. I am a bit skeptical at the moment and I wanted to hear from somebody else on the subject.

Is it normal? Is this actually a 4 wheel drive vehicle or just a marketing gimmick?

Thanks.

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Unread 11-30-2014, 07:45 PM   #2
caulk04
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It's not a typical 4wd vehicle like you're used to. It's still a front drive based vehicle, albeit with a PTO of sorts that runs the rear axle.

That's my take. Here's Jeeps info: http://www.jeep.com/en/4x4/#FreedomDrive1*
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Unread 12-01-2014, 05:50 AM   #3
Tyler-98-W68
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Not a marketing gimmick at all, the 4x4 lock level requests that the ECC (electronically controlled clutch) located just ahead of the rear differential be engaged as much as possible. Since the vehicle is fwd based there is a power transfer unit then a driveshaft to the rear end.

The driveshaft is always spinning so the delay for the back wheels engaging is very small. Since you can engage the 4x4 lock at any speed the ecc will lock and unlock rapidly to unsure that no drivetrain binding will occur.

The awd system isn't like a slip and grip system at all, It doesn't require any front wheel slippage prior to activating the rear wheels.

First video is with ESP Full Off Gear selector in [D] with 4x4 Unlocked
I put the Pat in drive and then slowly let of the brake waited a few seconds and slowly eased onto the accelerator

0:18-0:24 seconds is just idling

0:24s+ start applying throttle


As you can see the drivers front wheel does not spin (it is off the ground) and the passenger front wheel starts spinning fast and then slows down, which I belive is due to the ecc sending torque to the rear wheels, you'll notice once the front wheel stops spinning the Patriot lurches forward (indicating torque going to the rear wheels although it is hard to see in the video, I could feel it while in the Pat). The front wheel continues to spin at timed intervals (When my foot was off the gas). Indiciating the ECC was locking and unlocking. As I increase pressure on the gas pedal the front wheel slows and it seems the ecc is progressing to what seems almost full lockup before I let off the gas. My guess as to why the passenger wheel isn't spinning is because there isn't enough difference in the wheel speeds to make the BLD kick in. Had i given it more gas the Patriot would have driven forward off the jack.

Second video is with ESP Full Off Gear selector in [D] with 4x4 Locked.
I put the Pat in drive and then slowly let of the brake waited a few seconds and slowly eased onto the accelerator

0:16-0:21 idling
0:21+ start applying throttle


Whats interesting right off the bat is the behavior while in the locked mode when idling, it behaves exactly the same way as when the 4x4 was unlocked, lurching forward at intervals, once I touch the gas pedal everything locks up and unlike the AWD mode there is no progression with the ECC it's locked up until i release the gas pedal. In this mode if I would have used more gas I would have been able to drive off the jack.

Third video is with ESP Full Off Gear selector in [L] with 4x4 Locked. This is the FDII mode

I put the Pat in drive and then slowly let of the brake waited a few seconds and slowly eased onto the accelerator

0:16-0:21 idling, foot off the gas
0:21+ start applying throttle


In the FDII mode everything is the same as the 2nd video, rpms are higher and the Patriot seemed to be more eager to jump off the jacks (increased torque i'm guessing) The sound you hear at the end the the Pat shifting on the blocks (nothing broke)

I think that in all cases when the patriot operates in the AWD mode when there is no throttle is probably to prevent binding in the drivetrain at low speeds, i'm really intrigued how it works because the second there is any throttle input everything locks up (depending on the mode you are in)

In all cases above the patriot was able to transmit enough torque to move the vehicle forward, now whether or not it would be enough to drive over a small bump i'm not sure. Another thing to recognize is that the front wheels had ZERO traction, if your front wheels are on ice there is going to be at least some resistance so this isn't a 100% realistic test.


As the video states 1st part shows the AWD mode (FDI)

2nd part is the 4x4 lock in D also FDI

3rd Part is the FDII 4x4 locked in Low range.

You can also see the Patriot struggling to spin the wheels at times, not enough torque from the little 4 banger (and my heavy tires don't help either)

Here is a quote from part of the explanation of the 4WD system from jeep:

Quote:
OPERATION

The all-wheel-drive system requires no driver input or control. Under most driving conditions, it is passive and power is transmitted to the front wheels alone. Unlike all-wheel drive systems that rely on pumps or viscous fluids to transfer torque, this system requires no front-to-rear slippage for activation. This allows the system to transfer torque solely in response to accelerator pedal position. If the driver is asking for a lot of power, the system immediately starts clamping the electronically controlled coupling (ECC), transferring a high percentage of power to the rear wheels. This avoids front wheel slippage, as power to propel the car is transmitted through all four tires. This mode of operation is called open-loop operation in that there is no feedback to affect the torque transfer.

A second, closed loop, operating mode uses feedback from the wheel-speed sensors to determine the appropriate torque transfer. When the front wheels slip, the All Wheel Drive (AWD) Control Module tells the ECC to start clamping, sending power to the rear wheels. Attempting the same aggressive launch described above with the front wheels on ice and the rear wheels on dry pavement, the ECC sends even more torque to the rear wheels to minimize slippage and launch the vehicle. Both modes are always active with the closed loop mode layered on top of open loop mode to increase torque to the rear wheels when needed to maintain traction in extreme cases.
The AWD mode acts exactly as Jeep States and it appears the ECC is able to vary the amount of tourque going to the rear wheels. When the patriot is idling it appears to be in the "closed loop mode". Once you start giving it some gas then the open loop system also comes in and starts working. It also in my opinion shows that the isn't a whole lot of difference between the 4x4 locked (in D) and unlocked (in D) as the ECC nearly locks up in the AWD mode if you give it enough throttle.
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Unread 12-01-2014, 05:19 PM   #4
Karl1957
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Not real sure what those videos show. It looks like in video one, the engine is revving and only one wheel is barely turning. That's nothing to brag about. It's piss poor is you ask me. Higher engine rpm should mean faster wheel spin. Then video 2 shows something even worse. The engine revvs even higher and the front wheel turn even less. Somebody explain to me how high rpm and no wheels turning is supposed to power you through anything at all? Then there's video #3 which seems a lot like video #1. High engine rmp and one wheel barely turning. If this was in fact a real 4x4, that car would have driven off the jack at idle. Thanks for your videos. It proves my point. This vehicle is not a 4x4, rather a front wheel drive with piss poor performance.
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Unread 12-01-2014, 05:54 PM   #5
Tyler-98-W68
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Don't recall bragging anywhere. It was an informative post to help people out, but I guess not. Yes the vehicle would have driven off the jacks. The system transfers up to 50% of available torque to the rear wheels. The reason the wheels weren't turning is because if they did I would have driven off the jack. As for video 3 the lack of movement is the brake lock differentials clamping down on the wheels spinning in an attempt to get the vehicle to move forward as it has open diffs. Jeep uses brake traction control on all their vehicles. Problem is it uses far. More engine power than say a mechanical locking device. Patriots have a rather anemic 4 cylinder engine and not much of a crawl ratio so hence the bogging down and lack of movement.
Why all the negativity are you pissed off with your purchase of a patriot or compass. It isn't as ****ty of 4x4 system as you think. You must not have the fdii option like I do it makes the vehicle quote a bit more capable . offroad. No its not designed for hard core offroading but it does far more than you are giving it credit for.
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Unread 12-02-2014, 09:25 AM   #6
aroundincircles
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actually the patriot is a 4x4. As y ou are able to lock the power in a 50/50, up to I believe 35mph (which after that, there is no need for 4x4 anyways)

Having owned a patriot and a cherokee, The big difference between the two is how seamlessly the 4x4 is engaged. The patriot does it with a clutch, vs physically moving the gears like I do in my cherokee. I've driven my partents 04 tahoe off road, and shifting from 2 high to 4 high is nearly as seamless as it was on my patriot (4 low is a different story, but a patriot doesn't have 4 low)

Being in AZ I only had my patriot on snow once, but i've done A LOT of off roading. where 4wd was absolutely necessary. and with the advanced electronics, the patriot was actually pretty hard to get stuck. It could have stood more power, but hey, what car couldn't stand more power?

Here is a video where you can see the BLD (brake lock diffs) kick in, I had a FDII, which the BLD's are more aggressive than in a FDI, but they are still there.
https://www.youtube.com/watch?v=onp8cFOy_tc

This is an incredibly steep hill, which of course is not something you can see in the video. all I could see was sky when going up the hill.
https://www.youtube.com/watch?v=PR4K7U-JFro

Here you can see my back tire kick dirt as it hits a low traction spot:
https://www.youtube.com/watch?v=LpIfy6o5cAY
So the rear tires are getting traction.

This one I was stopped by the patriot's lack of articulation. I'm sure If I didn't have the wife/kids with me, i would have been able to make it, with a little bit more of a run up.
https://www.youtube.com/watch?v=B25ZHWp_j60
you can hear the thunking of the BLD's in the background. this hill had very deep holes and I often had only 3, and that last part just 2 tires on the ground.

Here is a video of me testing the 3 modes, 4x4 not locked, 4x4 locked, and 4x4 locked in low (FDII only)
https://www.youtube.com/watch?v=TLsaJqbu-0M
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Unread 12-03-2014, 04:46 PM   #7
Karl1957
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Appreciate the replies, I really do, but first off I don't have a Patriot. I plainly stated I have a Compass. I don't know anything about a Patriot, never driven one, and I don't care.

Secondly, yes I am a bit pissed off. I traded in a perfectly good Ford Bronco 4x4 and specifically told the salesman I wanted to replace my old Ford with a New Jeep 4x4. I picked out the Compass. It says 4x4 on the back. It says 4x4 in the owner's manual, and the salesman told me it was a 4x4. However, I have come to discover it isn't. It's what you call an "All Wheel Drive" vehicle with the bulk of the power going to the front wheels. It doesn't even have the power to drive off a jack if the front wheels are off the ground. That just isn't a real 4x4 in my opinion. I feel like I was lied to and mislead. But I've already signed the papers and I'm stuck with it.

I will chalk this up to a "Lesson Learned." Next time I buy a 4x4 I will make the salesman let me drive it through some Mud or Ice. This vehicle obviously won't do it.
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Unread 12-03-2014, 06:22 PM   #8
aroundincircles
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First off, patriot and compass are exactly the same cars. The only difference is sheet metal. Same engines, same transmissions, same suspension, same same same, Hence why people used patriots as examples.

2nd of all, the MK platform (what both the patriot and compass platform are bassed off of) is a 4x4 system. a 4x4 system is something that can lock the power in a 50/50 split which is exactly something the MK platform can do. the one thing that the MK platform is missing is a "low" set of gears. which is simulated in a Freedom Drive II MK, but not on a Freedom Drive 1.

3rd, if you don't believe that the MK can tackle mud and snow after watching tyler's and my videos then... well we cannot fix stupid. Sorry you are not happy with your purchase, but don't blame the vehicle, as it is a 4x4. Blame your lack of knowledge, and buyers remorse. The one thing that will give you problems on snow and off road are the tires. They put some really crappy tires on there stock. Get some good tires and you will be good to go.
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Unread 12-03-2014, 09:57 PM   #9
Tyler-98-W68
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It does have enough power to drive off a jack otherwise the above video wouldn't happen.

Or this

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Unread 12-04-2014, 12:01 AM   #10
aroundincircles
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I KNOW this video is not of an MK, but I drove my patriot on this almost exactly a year before this run was done in my XJ, and the wrangler that came with me was scared spitless, and was amazed I took my patriot through:
https://www.youtube.com/watch?v=9lSl...7OjtOfEf_2uoXw

here is my patriot in a different part of that trail, but it was NOT an easy trial in either the patriot or cherokee. but it was fun
https://www.youtube.com/watch?v=iGL0...7OjtOfEf_2uoXw
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Unread 12-04-2014, 12:03 AM   #11
aroundincircles
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you should watch some of the videos in this thread:
http://www.jeepforum.com/forum/f98/m...ideos-1553792/
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