5r55 torque converter getting old?

[akarro]

Hello

I have here on 98 year sohc with rebuilt 5r55. It got allmost all new parts servos, rebuilt kit, some hard parts etc.... So it was complete rebuilt. Only old thing was the converter what was not replaced. The car had 350 000km on it. Now it haves 422000km on it. It gives occasionally p0741 code.
It does it more often with warm wheater 20C and more. Transmission does not have any flares, just feel like it doesn not engage torque converter enought. It runs allmost perfect in cold days and the p0741 is a rare visitor.
In the hot days it just keep rpms at 3000 and and the transmission just waits something and acceleration is bad. In the cold days it is just like a rocket and transmission know exactly when and how to shift. I think it maybe a little bit a pressure related problem, since it is a temp related problem. It has also bad WOT start in hot days in D and 1st. Even does not have power to dig even a little bit. Is there any way to diagnose converter or is it reasonable to replace it anyway at the 422k km. The trans itselfhas all gears and does not have any flares. Is there any good way to diagnose converter, does not want to tear it down and replace if not shure. Hate to do it on the ground

best!

 

[akarro]

An update to my situation.

Yesterday driving highway speed torque converter started to kick on and out, about every 10 seconds. Desides to turn overdrive off. Drove like that about 30km then saw a mil lamp. I had simple scanner with me so got a p0715 code - TSS sensor circuit failure. Since that sensor is used to calculate lockup strategy I have now one idea: I have had random lockup issues with p0741 code, but after resetting it while driving, it locks fine. My guess is that maybe I have some kind on +12V supply failure. It should go together to solenoids and TSS. P0741 is the failure code what is calculated via TSS.
Maybe is the reason for it bad +12v on the tss. I am thinking power loss for a second or less via bad connector or corroded pins. I was that maybe the TSS sens less signal via voltage droppage and does couse p0741 code. I am thinking that because after cleaning p0715 have not seen it las days. Since tomorrow morning the tranny is acting fine again. Have any ideas?

 

[akarro]

A lot of time has passed and some things happened.
Finally the transmission lost some gears in autumn, so I took it apart.
The forward clutch was melted, oil pump was worn badly, cutted the torque converter apart, it was also full of metal and broken.
So got another donor tranny and ordered new converter, overhaul kit, servos and cvb valve body. The transmission was assembled by professional who has a lot of history with these trans in here because did not wanted to make any mistakes, because allmost all stuff was new what went in even bearings.
The result was very good, at least for the first 4000km had great throttle response, good shifts and basically was working as it should.
A few days ago it started to have minor flare 1-2 and very big flare on 2-3rd gear. Also what I noticed is a minor flare going into to 5th gear. I was thinking about pressure loss or bands misalignment, had some time, so readjusted the bands. overdrive band went one full turn more inside than it was. But no difference. It cannot be the new servo also. I am thinking about the epc now, does not want to go blind further, so try to get pressure readings.
Will provide some feedback when getting smarter and ofcourse good ideas are allways waited.

 

[akarro]

Today the transmission started to shift just fine, and a bit even better as it was at the beginning. So I am 99% sure that it is the epc what had or has some dirt inside of it. If does have shifting problems next time I will go with new epc.