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Some data on transmission performance


jeffhoward001

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We originally started talk about transmissions on my "285 vs 305hp" thread. Thought I'd share this new data on a new thread that's specifically focused on the transmission.

1) Can't remember who, but someone mentioned that "adaptation" in the TCU may make the transmission "feel" a little better after it adapts to my driving style. I'm happy to report, "Yes and Yes" :) After about a month of drive, shifts seem to be a little more crisp and it seems to down-shift a little sooner (which fits my driving style).

2) So the biggest annoyance now is the dreaded 35mph "death zone". I'll explain - Both me (the "car guy") and my wife (knows nothing about cars) both had the same fundamental complain - right around 35mph, (which happens to be the speed limit on all the streets with hills around our house) the DJ kind of "poops out". After some playing around with it, I realized that it's the shift from 3rd gear to 4th gear.

...It shifts into 4th gear, loses considerable power

...which forces you to press harder on the accelerator forcing a down-shift

...which in-turn surges the car forward

...which in-turn encourages you to let off the accelerator

...which in-turn causes an up-shift to 4th

...which in-turn... you get the idea.

It's most annoying on hills where the drop in power really matters. So I pulled some data on the HP/TQ curve of the Journey's 3.6L as well as some logged shift points at different speeds, and suddenly it all makes sense. The largest ratio-difference is between 3-4.

Referencing the data below, you can see there's a huge drop (36%) in the ratio difference between 3rd and 4th. While that in itself isn't a huge deal, it becomes a huge deal when you see how that effects the power output of the engine. The range from 2000-3000rpm is what I would consider the "bread-n-butter" RPM range for this engine during regular driving.

1st gear is really low, and the TCU knows it. So (this is my assumption) they programmed the TCU to hold 1st gear a little longer when you have anything more than moderate throttle pressure. This makes for slightly higher revs coming out of 1st, however it's a great shifting experience. It revs out to a little over 3K, which drops you nicely into 2200 rpm range in 2nd. PLUS, the power will always feel more responsive with higher ratios because the engine has more "cranking force" against the drivetrain.

They did a great job with the 2-3 ratios by dropped the ratio between 2nd and 3rd to just 19%. Again, this provides a great shifting experience because the drop in percentage difference means a 3K rev in 2nd will drop you into a nice spot on the TQ-curve in 3rd @ around 2500 rpm.

So here's the rub... They screw it all up with 3rd to 4th. Like I was saying before, the higher the ratio, the more "pull" the engine has against the drivetrain. So they really shoot themselves in the foot on 3rd to 4th. They not only exceed the transmission average of around 30% per-shift, but do so (unfortunately) at a VERY critical time in the driving experience (~35-45 mph). Looking at the data, you experience (roughly) a 55hp drop in power when the engine shifts from 3rd to 4th @ 3K revs.

Rarely does data so perfectly match real-world situations, but that is exactly what it feels like. 1st, 2nd, and 3rd feel like a nice well-tuned V6, then when it hits 4th, it feels like you took the engine out of my wife's Civic and dropped it into the Journey. Which, given the HP numbers at the 1800rpm, that would be a pretty accurate comparison!!

So what's the fix? I think two things: 1) They need to have the transmission hold 3rd longer, especially when there's additional throttle pressure. The easiest way to "detect" a hill is simply by measuring throttle pressure against speed. On a 6% grade, you will likely need to press the throttle 25-30% more to achieve the same acceleration as you would flat ground.

2) I don't know if this is getting too complicated for TCU programming, but when it detects a down-shift from 4th to 3rd, I think it would make sense for it to continue holding 3rd even if the driver lets off the throttle a little. This would prevent the vicious down-shift/surge/decelerate/up-shift situation I described above.

Longer-term fix would be to actually use the funky "fourth-prime" gear as a regular gear, and spread the ratios out a little more over seven gears (yes, there's a hidden seventh gear inside all of your Journey's :) )

Shifting_Data.jpg

Journey_HP_TQ.jpg

post-9617-0-42338000-1413493665_thumb.jp

post-9617-0-70852100-1413493666_thumb.jp

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This is exactly what I experience too! I think I complained about this a while ago. Thanks for confirming this...

In my own demented way of thinking, I think the Journey uses some kind of "optimistic" shift logic.... Meaning, in order to meet it's fuel efficiency ratings, it will shift up whenever possible even when we (as drivers) know that shifting up will not provide enough power to maintain speed at the given pedal position. It just shifts up, slowly bogs down, then shifts down again... repeat and rinse until you get to the top of the hill.

I also live on a hill and I experience this daily just like you described. I also notice that the engine is not as fuel efficient as what the ratings say they are. My guess is that they only managed to get these ratings using tricks like the up shifting to lower the RPM's etc.

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Exactly!! Thannks so much for putting this into easily understood terms. Like I said before, I hope someone develops a tuner and addresses this. My Dakota was the same way. They designed the transmission to get into overdrive as quickly as possible. My superchips tuner allowed the trans to hold gears longer before shifting. Boy did it make my truck fun to drive after that!

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I would agree 100% with both of you... I suspect this has something to do with fuel efficiency. Which in all honesty, I wouldn't mind that shifting behavior if I had a choice. For example, on my Audi it had a "sport mode" which was nothing more than a single sent to the TCU (position on the shifter) that made the transmission hold the gears a little longer and downshift a little earlier.

It's genius because in "regular" mode it up-shifts super early and uses "throttle adaptation" which actually makes the throttle "softer" so to speak, which in turn makes for less downshifts when the driver adds only slightly more throttle pressure. So instead of me just complaining more, onto solutions :)

I'm going to give Dodge a call about the TCU update (if any exist for my 2012). I think that's a good start.

I'd also like to look into after-market TCU flashes for Dodge TCUs. I know some exist for the higher-end SRT's and such, but haven't looked into anything for the Journey. A switchable "sport" and "economy" mode would be amazing, but who knows if that exists.

If I find anything, I'll be sure to report back to the forum.

Edited by jeffhoward001
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  • 2 weeks later...

Superchip = a way to separate unknowing people from their money.

It fools the computer driven parameters of some vehicles into using

gas to air ratios that are supposed to generate more hp and better

gas mileage.

INCORRECT

Superchips is a tuner company that cracks into the vehicle programming and changes parameters that affect driveability, shift points, HP, torque, fuel economy and so on... Superchips is a reputable and proven company that provides a quality product which performs exactly as stated. I owned one for my Dakota and Ram and they are well worth every penny...nothing available for the DJ though.

The cheap ass chips on eBay are the ones you are talking about.

Edited by Lobitz68
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Troll. We would not be good neighbors.

791 posts and the second most likes on the forum behind the moderator. Clearly I am not helpful on the site at all and just a troll... There is no fix, deal with it until Chrysler does (not going to happen). My advice works just fine on my DJ. If you're going to come to the forum with a pissy attitude and start calling people names you aren't going to get very far... Feel free to go somewhere else and ask for help, see where that gets you. Tool...

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Excuse me, but you were the one with the Abrupt, smart a** reply. "Live with It".

I'm done with this duel. Sorry if I got "Pissy" !!

Nothing smart ass about my reply at all... I deal with the shift by accelerating faster. Since there is no way to adjust the shift points or characteristics of the transmission, that is the only way I am aware of "fixing" the issue. When you accelerate through it a little more aggressively it isn't nearly as noticeable and I have not found it to be an issue. You could also use the manual shift, but that gets a bit cumbersome in traffic.

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I much prefer this reply and explanation. Sorry we got off on the "wrong foot".

I tend to try and poke a little fun on the board (all in good fun) in my replies when they don't need to be too detailed... You'll pick up on that soon enough. Life is too short to be serious all of the time.

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  • 1 year later...

Hey fellas I think I might have an idea for this 30 mph 4th gear, the reason is because the moment your DJ does its 3-4 shift @ <15% throttle its going to instantly lock up the torque conv.

Now my idea is to some how toggle that signal to lock up so if anybody has pinouts for the 62te I would gladly test me theory and post results.

BTW I've drove mine cold the other day and it did not lockup instantly going 3-4 and it was perfect!! but then it got warmed up and back to being lame 4th gear lockup:(

Also, I know im sorta fresh around here but I have dabbled with TunerCat a lot in the past which is mainly for z28s but the point is its simply an adjustment of a table in the TCU.

Any lockup under 45mph to is just retarded to me, probably because I have never owned anything dodge up until this past summer..

Edited by Sean Albin
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I was going to say the exact same thing. The transmission is locking up too soon. Most of the above members are no longer around, but there is a very easy fix to this. Go to the Dealer and tell them that your transmission is locking up too soon. They can adjust the speed at which it locks up. Your MPGs may suffer a little. I have had this done to my 3 previous vehicles and it was like getting a new car. No need to have it done on my DJ, because I have never experienced any of this. I did remove my resonator.

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Glenbrook. 5 Star. No issues. Ever.

Now, back to the thread. I do not believe that the transmission actually locks up until it is in 6, and settled out. I can feel it lock: like a seventh gear. Just leave it in 5 and see what you get. I did this one time and forgot I was in 5. It will take off in 5, but at a very leisurely pace! LOL

Edited by dhh3
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Haha thats funny man. If im driving in manual mode it'll automatically downshift for me as i come to a stop. What makes me feel like its locking in 4th @30mph is because if im using the autostick and leave it in 4th it wont slip unless you go all the way WOT. Will Glenbrook give you any options on choosing a lockup at all and how much was your bill after each time? Thanx a buch

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  • 2 weeks later...

So I made my trip up there Monday afternoon and they fed me the same crap.."we can only flash what Chrysler sends us"

which I understand but still kinda confused did you have your journey flashed or was it a different car? I even mentioned that I spoke to a person

online about all this and said they had it done and they still were kinda helpless in this situation...btw I now know that if you drive with a trans temp lower than 50 degrees F.

it will not lockup, if only I could just have access to alldata still...

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Both my 2006 Jeep Commander and my 2011 Dodge Nitro locked up prematurely, and I had them bump up the lock-up speed. Maybe they did this for me because I have been a customer for so many years. The DJ seems to be OK, so I haven't asked them to do it.

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