TransMichigan

[XWrench3]

I have never really liked the way my transmission has shifted, but I did not know if that was just the way it worked, or if there was an issue. At least until my daughter purchased her Liberty and I drove it. Her Lib's shifts the way it should. Evenly spaced all the way through, unlike mine that shifts 1----2---34 o.d. converter lockup all happening way to fast. without a kickdown linkage, what tells the trans to shift? it has to be the computer, but what tells the computer when to shift? is there anything that I can "tweak" in order to change the shift points in my Liberty's transmission? I have been living with the way mine shifts, unless I am getting onto a highway, or hauling a trailer, when I just manually shift the trans, and of course lock out overdrive. I have done that during regular acceleration from time to time, which of course gives me the shifting that I like. But sometimes that is impractical.

 

[04Liberty]

When I saw the title, I was really curious as to where this post was going lol. To answer your questions in order:
- If it is an 02-03½, the TCM does (45RFE). If it is an 03½+, then the PCM does (42RLE TCM function is combined within).
- The innate programming, these transmissions are fully electronic.
- No on both counts, unless you or someone you know has the hardware & software know how to hack OEM computer modules and alter those lines of code. The only thing that might work for the RFE is trying the TCM from a different RFE equipped vehicle that still used a standalone TCM (later RFE vehicles like Rams & Grand Cherokees got a combined PCM/TCM module, which allowed for some trans tuning to occur).
- Both the RFE & the RLE in most of their installs are programmed with fuel economy in mind; get to 4th gear as fast mechanically possible unless you're winding each gear out or manually shifting. The 04 we had (RLE) I would drive around town with the OD off and leave it off unless I was getting a long stretch or the highway.

 

[XWrench3]

That's kind of what I was afraid of. my lib is an '05 with the 42rle. I guess I will just have to live with it. "tuned for fuel economy" is a joke. we are driving basically a 2 tiered brick around, and for the life of me I can not understand how your going to have good fuel economy at any speed over 30mph when you have the aerodynamics of a pair of off set bricks. of course, higher compression and bigger cams in the engine would help, but that opens a brand new can of worms.

 

[turblediesel]

I think Green Diesel Engineering (GDE) brought back their transmission tune but you might need the diesel engine. Maybe there's a market for a transmission tune matched to the v6.

 

[JibeHo22]

Before you go off the rails with complex troubleshooting, I would suggest you force the electronics to re-learn the shift points. This is a link to a different forum that has instructions for forcing the transmission to re-learn.

transmission dilemma

www.jeepforum.com

I have an '05 Liberty and that procedure resolved an issue I was having a couple of years ago. Although I don't recall what the symptoms were.
If that transmission re-learn doesn't help, then dive into more complex troubleshooting.

 

[XWrench3]

OH NO! I guess I shouldn't have complained. Today I went to leave a shop, and when I moved the shifter from reverse to drive, and started to accelerate. the engine reved and about a second later the trans slammed into 1st gear. this happened all 3 times that I moved the selector from park or reverse into drive today after the first time. My first thought was the fluid might be low, but the level was fine. If the transmission fails, I will not be able to replace or have it rebuilt. I guess it would make a good parts car for my daughters, but that still leaves me without a vehicle. shouldn't the transmichigan throw a fault code if there is a problem with it?

 

[JibeHo22]

My 05 Liberty with 145K on transmission does the same thing occasionally.
When shifting from Park or Reverse into drive, you may be able to mitigate the problem you describe by using this sequence:
[Park or Reverse] -> [Neutral] -> wait 15 seconds -> [Drive].

 

[LibertyTC]

Even though you may think the ATF+4 fluid level is fine on the 42RLE, it probably is a tad low.
I slightly over fill it & the sloppy shifts are gone.
When I start the Jeep cold, I also place the Jeep into Neutral, for a minute, then shift into drive or reverse.
If problems persist, any transmission place with a shop scanner can read any pending or stored transmission codes.