Transmission help

09strokerpwr · Apr 20, 2019

So back story is I had a stage 3 trans from Rudy's diesel. Tuned by ******* sotf. Put 40000 on trans without a problem. Last fall was driving my truck and when the converter locked it let go. So took to a local shop and found that the billet input shaft was snapped, toasted the converter. So he built me a new trans with better shaft new precision converter and clutch packs. So after getting truck back I took it easy on trans for bout 600 miles. Then one night driving I went to pass a car with the converter locked up. Something felt off could feel a vibration and seemed low on power. Soon as I let up on throttle went away. So on next stright away I gave it again and same thing. I monitor torque converter slip on dash daq and seen the number spike all the way up to 700rpm. Took the truck back to trans shop showed him what was happening. He took the trans out went threw it and got a new converter. Only to have same problem. Truck has now been there almost weekly since December. He has replaced torque converter 4 times tried different brand this last time. New value body, all new solenoids, 3 different pumps. 1 used working and 1 new from Ford. All new pressure switches, springs and even a brand new tcm. I have tried returning truck to stock and redoing tunes only to have some results. I'm starting to run out of patience and he is running out of ideas. So far this hasn't costed me a dime besides the inconvenience of dropping truck off Sunday nights and picking up Friday night and getting rides to and from. Other then the converter not holding under lock up with a load on it trans shifts and works great. Open to ideas or suggestions. Thanks

EPA · Apr 20, 2019

Maybe wrong fluid... Could low line pressure cause this? Maybe cooler is all clogged... Maybe a contaminated cooler is causing the new tc to fail. I have no clue these are some ideas... Hopefully some other members chime in soon.

Lipka101 · Apr 21, 2019

09strokerpwr said:
So back story is I had a stage 3 trans from Rudy's diesel. Tuned by ******* sotf. Put 40000 on trans without a problem. Last fall was driving my truck and when the converter locked it let go. So took to a local shop and found that the billet input shaft was snapped, toasted the converter. So he built me a new trans with better shaft new precision converter and clutch packs. So after getting truck back I took it easy on trans for bout 600 miles. Then one night driving I went to pass a car with the converter locked up. Something felt off could feel a vibration and seemed low on power. Soon as I let up on throttle went away. So on next stright away I gave it again and same thing. I monitor torque converter slip on dash daq and seen the number spike all the way up to 700rpm. Took the truck back to trans shop showed him what was happening. He took the trans out went threw it and got a new converter. Only to have same problem. Truck has now been there almost weekly since December. He has replaced torque converter 4 times tried different brand this last time. New value body, all new solenoids, 3 different pumps. 1 used working and 1 new from Ford. All new pressure switches, springs and even a brand new tcm. I have tried returning truck to stock and redoing tunes only to have some results. I'm starting to run out of patience and he is running out of ideas. So far this hasn't costed me a dime besides the inconvenience of dropping truck off Sunday nights and picking up Friday night and getting rides to and from. Other then the converter not holding under lock up with a load on it trans shifts and works great. Open to ideas or suggestions. Thanks

Who’s tunes? I had similar issues with GH tunes after I built mine. I ended up running tyrants tunes.

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09strokerpwr · Apr 21, 2019

S p a rtan. I never had a issue with the other built trans. He even swapped a stock one in this week and tuned for a stock trans with same results.

White_monster · Apr 21, 2019

If it's doing the same thing with two different transmissions and different tunes I'd start looking at other components. Axle wrap maybe, usually only notice it on take off though.

EPA · Apr 21, 2019

White_monster said:
If it's doing the same thing with two different transmissions and different tunes I'd start looking at other components. Axle wrap maybe, usually only notice it on take off though.

How would this cause the tc to slip 700rpm when locked up?

09strokerpwr · Apr 21, 2019

You can make it slip under load watch it on the gauge let off just a bit and feel it grab and drop back down to no rpm slip

White_monster · Apr 21, 2019

EPA said:
How would this cause the tc to slip 700rpm when locked up?

Sorry missed the torque slip part

09strokerpwr · Apr 23, 2019

09strokerpwr · May 2, 2019

Ttt any suggestions?

makaveli200369 · May 9, 2019

I would look into the wiring harness that goes from the ECU to the TCM. Inspect the whole thing ohm out all the wires.

This is a long shot but on the 6.0 the electronic cooling fan clutch shares the same power supply as the transmission sensors/power. When the electronic fan clutch shorts out it causes transmission problems. The TCM might share the same VBPWR as the fan clutch. Can you unplug the fan clutch and see if the problem goes away?

Thanks