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#174 of 176 Re: transmission not shifting [jojopf99] by marcky

Dec 18, 2012 (12:02 pm)

Replying to: jojopf99 (Dec 17, 2012 8:06 pm)

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#175 of 176 Jeep CRD Shudders during mild acceleration through 50MPH by marcky

Dec 18, 2012 (12:40 pm)

This question keeps popping up, so I thought I would start a new thread.
 
You guys are definitely experience torque converter issue aka TC chatter. In our jeeps, the TCU signals the torque converter to lock-up (by openning a solenoid and allowing pressurized tranny fluid into the TC). The factory set point for TC-lockup is around 52'ish miles per hour. Under light acceleration, especially when towing, my truck used to try to TC-lock up and you could feel and hear from pretty ugly shuddering. I noticed that, once past that 50'ish speed range, I didn't have the problem.
 
One person mentioned that turning off the OD helped. That's diagnostic of the problem; turning off OD instructs the TCU to never TC-lock-up.
 
I did try running a couple of thousand miles with a friction modifier, that doesn't help. The TC is metal-on-metal, not tranny clutch material.
 
I did some checking and my factory 2005 CRD TC was replaced under the recall with the "more robust" TC and (I am guessing) the dealer applied the detune flash to the ECU to drop the engine torque output by 10%. That's what the recall called for; nerf your turbo.
 
If you continue to have this problem, the only ABSOLUTE way to fix it is to increase the line pressure in the Tranny by putting a resistor on the "tranny pressure valve" (it's a solenoid that increases the pressure throughout). There is a shift kit out there that also replaces the accumulator springs for more snappy shifts (which will also improve your tranny life span). And..... probably replace your TC with an after-martker (ehem *cough cough* properly engineered *cough*) component. If TC replacement becomes necessary, I stronly recommend this http://www.suncoastconverters.com/shop/jeep-liberty-diesel-torque-converter/
 
These suncoast guys have built stronger TC's that will stand up to the pummeling from a torque-ey CRD.The Green Diesel guys recommended this part so as to handle their "FT ecotune" that takes the motor up to 335 ft/lbs of torque, even in lock-up.
 
Good luck all. Hope that was helpful.

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#176 of 176 missed shift by cachedog

Apr 05, 2013 (4:43 pm)