Originally Posted by Nate769

DO NOT use a 2010 tuner on a 2011, there is a reason you can't find tuners for the 2011s yet. All the companies are having a REAL hard time cracking the new encryption on the PCMS. I was speaking with superchips and Bullydog, I am set up to be a beta tester for bullydog when it comes out, they said they were close but that was a month ago. You probably wont even be able to get a tune into a 2011 with a 2010/09 tuner, but don't take that chance in trying.

I don't really have a big issue with my Hemi and 4x4. Sure it goes down a little bit, but understand that your cruise has a little delay time, and if the hill is steep enough it does not take long to bring you down a little bit. Tow Haul mode I do believe changes the shift patterns in the tranny, and if I am not mistaken removes the 5th gear and shifts the line. This is why you will not get OD, and therefore MDS. MDS (only activates in OD) takes .4 millseconds to engage and disengage so that being the delay is not likely. I know that you don't have a 5.7, but thats just for those reading this thread. Often times my truck does not even gear down going up hills, only the really steep ones. That I think is what you could be seeing with your delay. Do as one guy stated here, if you feel your truck lagging, just bump your shift lever back and manually put it in 4th. Or just pull it out of OD. Or just take it easy and let the truck do its thing, you possibly save fuel then :P

And the tranny changes "a little" on the 2012 models, basically they just added another gear into them if im not mistaken, and shifted some patterns around. As far as I know there is no tranny differences between 09-11

Originally Posted by Arachnyd

I guess I dont understand automatic transmissions. Still don't get how a 5 speed transmission has 6 speeds.

That seems to me like it would then be a 6 speed transmission.

Does that mean the 2012 6 spd has 7 speeds? and then the older 4 spd has 5 speeds, and a 3 spd has 4 speeds?

I swear my old 4 spd only had 3 shift points...

Originally Posted by Nate769

Overdrive is not part of the "speeds" in a tranny. You could technically say what you are stating above with a 5 speed being a " 6speed" BUT because OD only kicks in when the motor recognizes that it can reduce the RPM that is void. If you notice when you are driving your RPMS are very low compared to being in 5th? Thats all that overdrive does, its designed to keep RPMs low to maximize fuel economy when engine power is not needed. If you put down the pedal just a little bit, notice that the RPMS go up but the truck does not really "shift" Thats OD kicking in and out. You will never see a case where you are accelerating in your OD gear.

Originally Posted by oldjeep

You don't really get measurable power drain from a modern transfercase when it is in set 2wd. Its just a straight in and out, the chain doesn;t spin in 2wd.

Originally Posted by Arachnyd

Doesn't the transfer case introduce 2 new ujoints? (at least the 2nd gen does, I haven't gotten underneith this truck yet). and doesn't the simple addition of a ujoint reduce power to the wheels by 7%-14% dependent on the angle, therefore robbing about 18 HP from the engine in this application? (or about 24 HP on the Hemi)? On top of that you have increased front wheel resistance and significantly added weight. I do believe your comments on the transfer case are valid, as traditionally 4x4 transfer cases were a cause of serious power robbing, but its still not a wash.

Looking for factual data, the best I can come up with is the Fuel economy numbers. Why does the 2WD get 1MPG better in the highway and 1 MPG better in the city with the same engine? If its Weight or drive train, the same factors are a drain on performance. If its gear ratios then it can go either way, but since it appears taht its standard for the same engine/transmission/rear differential combination, that would suggest to me that its the transfer case and front end differences of the 4x4?

Originally Posted by oldjeep

The 4x4 trucks weigh an extra 250lbs and they sit differently than the 2wd trucks. You'll get some parasitic drag from the front axleshafts spinning the gears in the diff and driveshaft. None of that is going to keep the automatic from downshifting.