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-   -   2012 3.6 Transmission Weirdness (http://www.jeepgarage.org/f107/2012-3-6-transmission-weirdness-38918.html)

bkwbkw 03-14-2012 03:20 PM

2012 3.6 Transmission Weirdness
 
It appears that most of the tranny issues here are related to the Hemi WK2's, and I haven't seen many for the Pentastar WK2's.

We took our first major road trip last week with the wife's new WK2 and I noticed a few strange things with the transmission and want to see if its 'normal', or I should drop my service mgr a line.

At ~55mph uphill (~5* grade), the tranny wouldnt go into a lower gear without me stomping on the accelerator or manually shifting it into gear. RPM's would keep dropping in gear and I'd lose speed going uphill. When approaching another uphill climb faster (~70mph), the tranny would work as usual and kick down a gear to get me back into the sweet spot.

Another weird thing I've noticed is when starting from a stop up a grade, waits till I'm at ~4k to shift to 2nd. I'm not flooring it or anything like that, I'm giving it normal pedal pressure.

And finally, it feels like the motor stumbles when changing into the higher gears at lower speeds. Example, cruising at 35mph, gradually accelerate and it hesitates for a second. It feels like the ECU is trying to figure out if it should knock down a gear or not. There's definitely a little bit of hesitation there.
For this one, I'm thinking that it's normal because my JK does the same thing too, and that's because of the DBW throttle. After I put a superchips tune on it, this issue totally went away. But then I went to a supercharger with a different tune (non-superchips) and the hesitation is back.

Sorry about rambling, hopefully you guys can decipher what I've written and can help.

Skier95746 03-15-2012 01:00 PM

Re: 2012 3.6 Transmission Weirdness
 
For better or for worse, most of your experiences are consistent with my own. In Jeep's efforts to squeeze as much MPG out as possible, they seem to have impacted driveabliity more than I'd have liked. Some of the shift characteristics seem to be due to bigger gear spacing than the torque curve of the engine can tolerate and some (I believe) was done in the safe of fuel economy. I've gotten used to it driving around town, but everytime I drive up the hill to Lake Tahoe, I wish I'd gotten the V8...

tnjeep 03-16-2012 12:45 PM

Re: 2012 3.6 Transmission Weirdness
 
I don't know how many miles you have on yours but mine was kind of the same but gradually got better. It may have something to do with the computer learning but I have 1500 miles on it now and the shifting has greatly improved. The V6 is powerful but it is still trying to push around a nearly 5000 pound vehicle.

bmrisko 03-16-2012 03:34 PM

Re: 2012 3.6 Transmission Weirdness
 
I think a lot of it has to do with the fact that the V6 is slightly under-powered on a 5000+ vehicle and uphill grades make it even worse. Maybe a tuner will eventually be released where you can change shift points.

prelude532 03-16-2012 04:17 PM

Re: 2012 3.6 Transmission Weirdness
 
I would say I have a similar experience in my 2011 Laredo X, but I feel like the trans in the wife's 12 Limited doesn't suffer the same way. Driveability seems a lot smoother with the '12 V6, same for my father's '12 Overland with the same motor. Guess I set the standard too early.

BobsWK2 03-16-2012 07:00 PM

Re: 2012 3.6 Transmission Weirdness
 
Quote:

Originally Posted by bmrisko (Post 595164)
I think a lot of it has to do with the fact that the V6 is slightly under-powered on a 5000+ vehicle and uphill grades make it even worse. Maybe a tuner will eventually be released where you can change shift points.

I'm sure the 6 cylinder owners will be in here to argue about the 6 cylinder being plenty for the 5000+ weight of the WK2.

BimmerAgent 03-16-2012 11:08 PM

Re: 2012 3.6 Transmission Weirdness
 
It's not the engine, it's the tranny. The mapping is poor, and it has a hard time deciding when to shift, especially since it's coupled to a vague drive by wire throttle. The software updates have helped some, but it's still lazy. My nine year old BMW's 5 speed slushbox is a way better tranny, even if it is a GM sourced unit. Bruce

mr_bots 03-16-2012 11:55 PM

Re: 2012 3.6 Transmission Weirdness
 
I've actually been fairly impressed with the V6 in mountains. I've left cruise set and handled it myself, both seem to downshift to 4th and then 3rd to run up 20% grades going 80mph with the engine spinning about 3500rpm, doesn't even really sound strained. Granted the gear spread could be better...

padgett 03-18-2012 06:36 PM

Re: 2012 3.6 Transmission Weirdness
 
Not going to argue about the V6 though have pulled some serious grades with a rig and and less power, what I am hearing (five gears are plenty for a torque curve that broad) is a transmission that is not unlocking (feels like a downshift: trans will jump about 500 rpm and taking advantage of the torque converter.

Is easy to tell, just vary the throttle (not sure of effect of DBW). If unlocked you shold see a 400-600 rpm shift in the tach. If locked, you won't (can also monitor with a $30 scan tool). Haven't checked but suspect you can unlock by touching the brake enough to turn the lights on.

As to the 4000 rpm excursions, that is no big, redline is at about 6400 rpm, just really in the middle of the torque curve. This isn't a Buick. Think 327 SBC with a fat cam.

Do know the V6 is deceptive, is real easy to get going faster than you expected. That real flat torque curve doesn't have the normal feeling of gathering power. Have seen that before.

millzzy 03-19-2012 01:11 AM

Re: 2012 3.6 Transmission Weirdness
 
I have written / complained about this as well, is my only disapointment with a great car,the diesel i test drove was so much better,just couldnt run to the extra $6,000. I suspect my v6 doesnt produce enough torque down low in the rev range to compensate for the poor shift pattens, definetely better when in sport mode. Mine is now started to give a thud when pulling away from traffic lights, i have horrible feeling i may need my 5 year warranty.I certainly dont drive mine hard, i can get the EVIC to consistently go below 10L/100k :D

mickey53usa 11-27-2013 12:58 PM

Re: 2012 3.6 Transmission Weirdness
 
I have this same "hesitation" at low speeds. Travelling at constant speed - let off the throttle and drop speed - RPM's to 1K and then gradually accelerate and it feels like the engine drops off before it accelerates. Took it to the dealer - "could not duplicate problem." It almost feels like the torque converter locks and then does not unlock fast enough.

Might try another dealer -

COnative 01-14-2014 02:24 PM

Re: 2012 3.6 Transmission Weirdness
 
Same exact issue heres and it seems to be getting worse. I've had mine for about two years and only 5200 miles on it. 95% of the driving is 40mph or slower and it just seems like they didn't design this thing for in town driving. The couple times I've driven on the Interstate, it seems to do great but I haven't taken it up in the mountains yet.

But all the school zones I drive through going to work, it's a real downer. The torque converter will lock up at 20 mph (school zone speed) and also shift into 3rd resulting in an unpleasant rattle from the engine compartment for a second or two until it seems the computer adjusts valve timing or something and it quiets down. Or roll gently on the throttle to take off from a stop in slow traffic and the TC locks just before the shift to 2nd making the rpm drop to bit under 1K and even if I hold the throttle steady, the trans will downshift and the TC unlocks and it gains speed, holds 1st like it should have to begin with.

The thing that really bugs me is this thing was so smooth and the trans seemed to always be in the right gear when it had 600 miles on it. But then things started failing (all tires needed to be replaced because they couldn't be balanced and were determined to be out-of-round, load leveling shocks were replaced because of noise, ABS and traction control sensors replaced because of MIL).


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