wont upshift under hard acceleration

[bigyellowjimmy]

Hello all,

I've got an 02 Liberty 4x4, 3.7L, 45RFE ******. We bought it on 4/7/13 with 116,500 miles. It now has 129,000 miles.

Under heavy acceleration (basically floored) the transmission shifts down, the engine hits 4500 RPM's and it wont upshift and accelerate unless I let my foot off the gas. We see this problem mostly when climbing hills at highway speed and attempting to accelerate when merging into traffic or in a panic situation.

Also, we have the code PO740, occasionally the CEL goes off by itself but its on most of the time. The transmission shifts fine typically although once on a long road trip with the cruise on it shifted down on a hill and the ****** locked into either 2nd or 3rd gear, I cant remember. I have a scanner and the next morning I cleared the code but the ****** was still locked in gear. After a little while driving it began shifting normally again.

I've heard the PO740 means the converter clutch was slipping when it was supposed to be locked up. Often due to dirty or not using ATF+4 fluid. I've changed both transmission filters twice and always used ATF+4. The fluid is clean, there are no external leaks. Also heard the valve body seal could be leaking internally or the TC solenoid could be going bad.

I don't know if these two issues are related but mostly want to know if anyone has had the ****** kickdown issue and how you resolved it.

Thanks

 

[Hedsic]

Sounds like it's possibly not a good thing.

http://www.jeepforum.com/forum/f28/cel-code-po740-torque-converter-clutch-1531093/

 

[TwoBobsKJ]

Sounds like it's possibly not a good thing.

CEL Code PO740 Torque Converter Clutch - JeepForum.com

Good find, Hedsic :waytogo:

Bob

 

[bigyellowjimmy]

Sounds like it's possibly not a good thing.

CEL Code PO740 Torque Converter Clutch - JeepForum.com

Regarding the PO740 code.......the thing is I don't get TC shudder, the only time there has been any mechanical transmission symptoms is last summer when it stuck in gear as described in the 1st post. Weird.

Any thoughts on the floor it/downshifts/doesn't upshift/engine doesn't rev past 4500 rpm/therefore doesn't accelerate unless let off gas?

Thanks

 

[02redKJ]

Weirdest thing ever. I was out of town this past week. On Wednesday, I left the hotel and got on the freeway. Besides the inclined on ramp, the freeway goes up hill too, which creates the same scenario that BYJimmy has described. My 02 3.7 with the same trans did the same thing. Mine went to 5500 rpm before I could let of the accelerator though. Big rig behind me was going to kill me if I didn't get out of the way. When I let off if shifted. Then I tried to speed up and it went braaaauuuum, and slowed down. The dash lights flashed away, the cel too, and I could only feather the throttle to keep it at 55 or 60mph. I dropped my son off and then went to OReilly auto. The engine sounded like I hadblown it or something. It was missing like crazy. I stopped the engine and sat there for 10 minutes. I started it back up and it was smooth and no longer missing. I had the counter girl pull the codes for me. She did, and it was a po302 code. I had her clear it for me and then drove the rest of the week and back home and all weekend. I drove it over700 miles this past week. I'm guessing 450 of that had been since the code was thrown. It hasn't done it since, but I haven't really stomped on it since either. Sort of afraid to.

 

[bigyellowjimmy]

Weirdest thing ever. I was out of town this past week. On Wednesday, I left the hotel and got on the freeway. Besides the inclined on ramp, the freeway goes up hill too, which creates the same scenario that BYJimmy has described. My 02 3.7 with the same trans did the same thing. Mine went to 5500 rpm before I could let of the accelerator though. Big rig behind me was going to kill me if I didn't get out of the way. When I let off if shifted. Then I tried to speed up and it went braaaauuuum, and slowed down. The dash lights flashed away, the cel too, and I could only feather the throttle to keep it at 55 or 60mph. I dropped my son off and then went to OReilly auto. The engine sounded like I hadblown it or something. It was missing like crazy. I stopped the engine and sat there for 10 minutes. I started it back up and it was smooth and no longer missing. I had the counter girl pull the codes for me. She did, and it was a po302 code. I had her clear it for me and then drove the rest of the week and back home and all weekend. I drove it over700 miles this past week. I'm guessing 450 of that had been since the code was thrown. It hasn't done it since, but I haven't really stomped on it since either. Sort of afraid to.

Yeah, really odd. My dash lights dont flash and my CEL comes on periodically just driving normally (always 740 code).

For everyone else, when you floor your Liberty does it shift down and then upshift while still floored or do you have to let off the accelerator before it will upshift?

 

[dude1116]

Yeah, really odd. My dash lights dont flash and my CEL comes on periodically just driving normally (always 740 code).

For everyone else, when you floor your Liberty does it shift down and then upshift while still floored or do you have to let off the accelerator before it will upshift?

42RLE downshifts and upshifts appropriately.

 

[bigyellowjimmy]

42RLE downshifts and upshifts appropriately.

Thanks dude for the response. I assume those of you with the 45RFE can floor it, ****** shifts down and then upshifts without lifting the accelerator?

 

[CobraNutt]

I don't know that I've floored my Libby yet...which is really quite odd considering I put the hammer down in the Mustang quite regularly! I suppose I just have different expectations between the two rigs. :33:

Many automatics will hold a lower gear under WOT until redline or maybe even higher. I know that my old AOD's in my TBirds would, if I wasn't careful. The Libby might act the same way so that it holds the lower gear until a certain RPM and engine load is sensed, or until the throttle is lifted a bit. Don't know for certain though.

 

[dude1116]

Well if it's worth anything if I'm flooring it, the Jeep will hold on to 2nd gear til about 5,300 RPMs. Which is fairly close to redline (~300 RPMs til redline). I'm not sure how close you let the Libby get to that...at that point I'm doing about 70MPH (the disadvantage of only 4 gears).

 

[CzarKJ]

This seems like a dangerous thread and there will be a bunch of liberties flooring it at red lights looking at their tach lol

 

[bigyellowjimmy]

Thanks everyone, when mine kicks down the rpm's get to around 4,500 - 5k and it wont upshift. The engine bogs down (it feels like it hits a rev limiter). I must lift off gas and it will shift to next gear. Of course at that point I've slowed down enough that it really needs to downshift to speed up rapidly again. Going up a mountain grade at highway speeds or flooring it when entering freeway or getting out of the way of some crazy driver is when its noticeable.

 

[ob wan]

hi, has this problem been solved? mine is doing the same

rgrds

 

[ob wan]

any luck?

 

[vaksanov]

129000 miles is about when my transmission went out. Kept showing and clearing TC 0740 code. Shifted fine and smooth that I couldn't even tell something was up until I was driving on a highway and trying to accelerate it got stuck in 3rd. Once I pulled over it wouldn't even move 1 inch. So I had to replace it with a JY one with 67k on it since I couldn't afford to rebuild

P.S. Did you overheat your transmission? Did the transmission temp light ever come up? It did on mine on a trip and I think that's what caused the failure. I tried changing filter/fluid but that didn't help and it still went out on me.

 

[ob wan]

will the transmission input and output sensors throw error codes if it's faulty?