Originally Posted by Sliter'12Overland
I am confident that it has something to do with the new "6" speed shift mapping and the mds this new ratio and the cylinder deactivation needs fine tuning. If I put the ERS into 5 and drive normally it is perfect there is no shudder it is even more responsive and smooth in tow/haul, however mileage gets no help this way.
You do know there is no new ratio in the 6 speed, the ratios and gearing are the same in these transmission as the so called multi-speed in the 2011 as well as for years in Jeeps and other chrysler vehicles. Shift programing has changed over time. The torque converter was changed for 2012 in an attempt to better mpg with minimum harshness. Perhaps you are feeling the torque converter clutch engaging and disengaging as it flutters. This and the MDS would be most noticeable in 6th when the rpms are low. When you drive in tow haul or shift to ERS 5, the vehicle does not use the second overdrive (6th) where the flutter would be most noticeable. MDS is disabled in 5 (and ERS 6), so that eliminates that vibration (not sure if MDS gets disabled in tow/haul). Tow haul also adjust shift points to a higher rpm where smooth operation is easier to obtain.
So the jeep gives you a real choice between a smooth responsive vehicle and one that squeezes the last mile out of that gallon, with some harshness. There shouldn't be much harshness, however.
You may feel and hear some vibration when MDS is engaged and sometimes when driving in second overdrive due to the torque converter flutter, thats just the way it is.. normal for these vehicles.