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  #13  
Old 01-16-2011, 08:01 AM
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Re: HEMI hestitated and "shook" during W.O.T.

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Originally Posted by mwhited View Post
If you were running at 45 in Eco mode, it almost sounds like there was a delay for all eight cylinders to kick in, thus the full throttle 4 cylinder shutter.
That's exactly where I was: 45mph ECO mode, then punched it to the floor, the engine "shuddered" for 1 count, 2 count, then it kicked in and responded.
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  #14  
Old 01-16-2011, 08:09 AM
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Re: HEMI hestitated and "shook" during W.O.T.

Awesome Jeff, thanks. I'm an idiot, but what is a "Star Case"...my Overland was built Dec 2010 (the TSB says Jul 2010), but the problem it describes is exactly what we have! I haven't tried sport yet but will next time. In sport mode it really is only in 2WD right?
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Old 01-16-2011, 09:57 AM
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Re: HEMI hestitated and "shook" during W.O.T.

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Originally Posted by THEPRFCT10 View Post
Awesome Jeff, thanks. I'm an idiot, but what is a "Star Case"...my Overland was built Dec 2010 (the TSB says Jul 2010), but the problem it describes is exactly what we have! I haven't tried sport yet but will next time. In sport mode it really is only in 2WD right?
Post #96 by Milous: Did Shudder TSB fix a problem? Shudder problems thread.
"It has not been escalated to TSB status. The reference is "Star Case # S1021000002". (I think this means they know there is a problem, but it isn't a big enough problem to make it a TSB.)

As far as sport mode goes, I understand 80% of the torque is moved to the back wheels. Also the ESC is turned off. I don't think it's in 2WD, just a modified 4WD. I could be wrong.

I picked a dealership that doesn't sell many WK2's. I can tell their service department is not up to speed with this vehicle. I'm about to try another dealer hoping they have delt with this problem already. Please let us know if you have any luck.
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  #16  
Old 01-16-2011, 10:18 AM
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Re: HEMI hestitated and "shook" during W.O.T.

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Originally Posted by JEEF View Post
Post #96 by Milous: Did Shudder TSB fix a problem? Shudder problems thread.
"It has not been escalated to TSB status. The reference is "Star Case # S1021000002". (I think this means they know there is a problem, but it isn't a big enough problem to make it a TSB.)

As far as sport mode goes, I understand 80% of the torque is moved to the back wheels. Also the ESC is turned off. I don't think it's in 2WD, just a modified 4WD. I could be wrong.

I picked a dealership that doesn't sell many WK2's. I can tell their service department is not up to speed with this vehicle. I'm about to try another dealer hoping they have delt with this problem already. Please let us know if you have any luck.
From what I've read I think you are generally right, it's an "up to" 80% rear bias on the transfer case and a "reduction" in the traction control, not "turned off".

Honestly, I don't think this is a mechanical problem or something that is wrong with this one truck. It could be fixed with a reprogram of the engine and transmission systems. I guess if everyone tried it, detected the same symptom and reported it to their dealer it might put the issue over the top and get Jeep to rework the code and generate a TSB.

Then again, is it a combination of conditions that's so rarely encountered that it's simply not worth the effort???? (i.e. an artificially induced set of conditions intended to result in a predictable, unfavorable outcome). I mean come on guys, it's a mechanical contraption, it should transmit some of that mechanical interaction back to the driver. In this case you are asking it to go from a EPA induced economy mode to a performance mode and do it seamlessly in a matter of a few milliseconds. Think of how long and how much "bucking" would take place if you did this in a truck with a manual transmission where the only computer is between your ears.

The more reasonable driving technique, and the one that's probably the way 99% of the people driving on the public roads use, would be to increase the pressure on the accelerator then eventually get to WOT if it was deemed necessary. The initial tip in of the throttle would have re-engaged the 4 silent cylinders and the increasing demand from the accelerator would have initiated a downshift. By "mashing" the throttle down you asked it to do all that in under a second so the system responded by enabling the additional 4 cylinders then going into torque limiting to prevent damage to the transmission during the downshift. They can program that shutter out but what you'll end up with a even more buffering between your requested input from the throttle and what the truck actually does.

Then again this is just my 2 cents and that won't even buy you a cup of coffee anymore
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Old 01-16-2011, 12:48 PM
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Re: HEMI hestitated and "shook" during W.O.T.

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Originally Posted by mjw930 View Post
From what I've read I think you are generally right, it's an "up to" 80% rear bias on the transfer case and a "reduction" in the traction control, not "turned off".

Honestly, I don't think this is a mechanical problem or something that is wrong with this one truck. It could be fixed with a reprogram of the engine and transmission systems. I guess if everyone tried it, detected the same symptom and reported it to their dealer it might put the issue over the top and get Jeep to rework the code and generate a TSB.

Then again, is it a combination of conditions that's so rarely encountered that it's simply not worth the effort???? (i.e. an artificially induced set of conditions intended to result in a predictable, unfavorable outcome). I mean come on guys, it's a mechanical contraption, it should transmit some of that mechanical interaction back to the driver. In this case you are asking it to go from a EPA induced economy mode to a performance mode and do it seamlessly in a matter of a few milliseconds. Think of how long and how much "bucking" would take place if you did this in a truck with a manual transmission where the only computer is between your ears.

The more reasonable driving technique, and the one that's probably the way 99% of the people driving on the public roads use, would be to increase the pressure on the accelerator then eventually get to WOT if it was deemed necessary. The initial tip in of the throttle would have re-engaged the 4 silent cylinders and the increasing demand from the accelerator would have initiated a downshift. By "mashing" the throttle down you asked it to do all that in under a second so the system responded by enabling the additional 4 cylinders then going into torque limiting to prevent damage to the transmission during the downshift. They can program that shutter out but what you'll end up with a even more buffering between your requested input from the throttle and what the truck actually does.

Then again this is just my 2 cents and that won't even buy you a cup of coffee anymore
I agree with what you are saying 100%
I do think this is a software issue and maybe not worth messing with. Mashing down the gas from low speeds is not a normal driving condition. Although for me it kinda is. I drive many miles on county roads and end up power passing 3 cars at once often. This is when I feel the shudder the most. 45mph to 80mph as fast as possible. However there have been a few times I was just cruising at 30mph in city traffic and I feel a weird shudder. This bothers me the most.
Anyway I do think the shudder is getting better. I think my WK2 is learning I'm a controlled maniac driver.

It would be nice if we could turn off the MDS... Especially off road.
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  #18  
Old 01-16-2011, 01:45 PM
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Re: HEMI hestitated and "shook" during W.O.T.

Mine 2011 WK2 does the exact same thing... while driiving at a low speed and then Mashing the throttle to the floor as to pass somone, it starts to shudder and shake. I normally have to let of the gas and ease back into it in order to get it to stop shaking.

The funny thing is that my 2002 Ram does the exact same thing as well... but it happens more so when flooring it out of a corner and not as often when going in a straight line as the jeep does.

Not sure what the cause is, but its definately a 45RFE/545RFE issue that I would like to find a fix to. Im leaning towards programing.

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Old 01-16-2011, 05:39 PM
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Re: HEMI hestitated and "shook" during W.O.T.

Can you avoid the shudder by switching to manual shift mode?
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Old 01-16-2011, 05:51 PM
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Re: HEMI hestitated and "shook" during W.O.T.

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Originally Posted by tfinan View Post
Can you avoid the shudder by switching to manual shift mode?
Not for me. Tried that right away. I also thought manual shift mode would turn off the MDS, but found out I was wrong.
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  #21  
Old 01-16-2011, 05:52 PM
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Re: HEMI hestitated and "shook" during W.O.T.

This is SO not normal.

Dirty old WK Hemis don't do it, so why should the new "better" one!?!?!?!?!?!?!?!?!?!?!?!
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Old 01-16-2011, 06:02 PM
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Re: HEMI hestitated and "shook" during W.O.T.

I believe the Mercedes gl had an issue with overly aggressive traction control kicking in from a dead stop. I wonder if something similar made it into this design?


edit: sorry it was the Toyota Sequoia, a car I considered at the same time as the GL. It is obviously not in the same "family" as the jeep.

http://www.thetruthaboutcars.com/201...-deceleration/
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Old 01-16-2011, 06:25 PM
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Re: HEMI hestitated and "shook" during W.O.T.

Surely not from highway speeds!?

Although, I'd sure love a JGC that had traction issues from a 55mph roll! lolol
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Old 01-17-2011, 12:14 PM
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Re: HEMI hestitated and "shook" during W.O.T.

My dealership is trouble-shooting the 430N Sirius Trvale Link problem for me (like many of us my 430N does not display Travel Link), so I figured I'll ask them about this when I bring my truck in for the 430N stuff. I'll keep you posted.

I will agree that whereas I may not neccessarily drive like this 100% of the time (i.e. 45mph, then mash W.O.T.), I was doing this on a regular basis per the manual and many suggestions on this forum to break in the motor (I have less than 300 miles still). The shuddering caught my attention and since it does not do it all the time, tells me something may be wrong (or maybe I'm just a little impatient if this really is the torque converter needing 6000 miles to break in properly!).
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