Sudden Transmission Issue

[Broosedamoose]

The other day I was driving on a back road cruising at about 40 MPH when all of a sudden the RPM's started to climb and then there was a "clunk" and all was normal again. Well it happened again this morning. It feels like, if it were a manual, slowly pushing in the clutch and then sliding your foot off the pedal quickly. I just replaced the transmission about two months ago with one that had only 51k on it. I checked the fluid and it's fine. What could this be? It's a 2007 4WD with a 5R55E transmission.

 

[RonD]

Torque Converter is new?

Reads like TCC(torque converter clutch) is not staying locked
TCC was the first solenoid added to the "electronic" automatics, in the A4LD, 1985/6

One of the draw backs of using a torque converter is that it "slips", it has to so you can stop while in gear
But that also wastes fuel/power when its slipping
TCC locks torque converter above a certain MPH so is computer controlled, so less wasted fuel
Torque Converters lock on their own above a certain RPM, called "stall speed", usually 2,500+ RPM
So if just cruising along without TCC there would be some slipping causing dismal MPG, big fault in early automatics

TCC solenoid issue should set a transmission code, and OD light might flash as its slipping(1995 and up)
Transmission codes are at P07xx which most OBD2 readers can't see
P0740 Torque Converter Clutch Circuit Malfunction
P0741 Torque Converter Clutch Circuit Performance or Stuck Off
P0742 Torque Converter Clutch Circuit Stuck On
P0743 Torque Converter Clutch Circuit Electrical
P0744 Torque Converter Clutch Circuit Intermittent

I assume trans fluid was checked and at a normal level?
Low fluid would cause loss of pressure, which causes clutches and bands to slip

RPM increase without similar speed increase means something is slipping, I know DUH, but it is what you described

 

[Broosedamoose]

Thanks Ron! I'm going to bring it in today to see if my mechanic can pull a code. My scanner isn't showing any codes. It's able to read transmission codes but I'm not getting anything. May not have lasted long enough to produce a code. But yeah, it feels like the torque converter starts to slip and then locks up. It's not new one. It's the converter that came with the used transmission I bought. I'm hoping it's just a fluke or at worse, the solenoid! The transmission replacement cost me over $3k and it was only a couple months ago! Oh, yes, I checked the fluid and it's fine.

 

[Broosedamoose]

So we were not able to get any codes but the problem hasn't happened since. However, a new issue has come about. While on the highway, the RPM's will suddenly surge about 500 and then drop back down. It happens even with the Cruise Control engaged so I know it's not me pressing on the throttle. It happens randomly but continuously while driving. My mechanic thinks it may be the Torque Converter Lock Up solenoid going bad. There are still no codes so we can't be positive. What do y'all think?

 

[rusty ol ranger]

A TC solenoid should blink the O/D light (throw a code)

You dont have the general check engine on do ya? Or a screwy speedo?

 

[Broosedamoose]

A TC solenoid should blink the O/D light (throw a code)

You dont have the general check engine on do ya? Or a screwy speedo?

We checked for codes but there's none. My mechanic thinks it doesn't happen long enough to cause a code. It only happens like every couple minutes and just goes up and right back down. I have no lights on or speedometer issues.

 

[Broosedamoose]

So I'm going to go ahead and replace the TCC solenoid just to be safe. I don't want to burn up my converter. While in there, I want to put a shift kit in. Anyone know if there is much difference between the Trans-Go kit and the Superior kit? I'm just doing the valve body and not the clutch rings.

 

[Broosedamoose]

I decided to go with the Sonnax Zip Kit. Has anyone used this kit before?

 

[Beshires1]

My 1999 did the same thing. only it done it when taking of from stop while turning steering wheel. If done this randomly for years. I finally bought a remanufactured valve body off Ebay and it now shifts like a dream.

 

[Broosedamoose]

I had the solenoid and Zip kit installed and I didn't get 5 miles before the damn O/D Off light started flashing! I took it back and he pulled a code 741. There is a noticeable difference in the shifting and everything seems to work fine. It doesn't surge anymore. I'm wondering if the TCC Solenoid I bought is junk. I wanted to save a few bucks and opted for a reman instead of new. Might not have been a good idea!