P1728 - Transmission Slip Fault

[jschildm]

1997 F-350, TS Chip with Gearhead Tunes, Adrenaline HPOP, same transmission its had since I got it 110k miles ago (presumably stock or stock rebuild as there is currently about 246k total on the truck).

For the last couple years I would very occasionally get a P1728 code. This would only happen while towing a gooseneck horse trailer. It would typically trip on a really windy day up a hill. I would never actually feel any slip or feel abnormal function. I would clear the code and it would be fine for 6 months. Fast forward to this summer and it has occurred more recently. Then finally one trip to a horse show it tripped, and then proceeded to trip even driving empty. This was the first time that I felt as though it did not function normally as the DTC was set. I made the just over 2.5 hour tow home without incident, though there is definitely something going on now, as it started out not wanting to lock the TC without me letting of the gas and giving it time to lock without load. By the time I got home, it would stay locked nearly all the time, except to stop, as though I was shifting a manual entirely to early.

Anyways, my internet research tells me it's likely a torque converter. I have 2 questions for the smart folks here:
1. Is there a way to diagnose if its the TC vs. a valve sticking, etc?
2. Does anyone have a recommendation for a good torque converter if it comes to that?

Thanks,
John

 

[jschildm]

No one even has a suggestion for a brand of stock/a little better than stock torque converter? @Mark Kovalsky is there a way to check solenoids or anything to troubleshoot, or do I just need to get a torque converter?

 

[Tiha]

Good Point, I was waiting for him to chime in and take care of this. But he must be busy.

I bought a TC from racerxusa. Pretty happy with it.

 

[Mark Kovalsky]

There are a couple things to do to diagnose what's wrong.

First, look at the front of the torque converter. If the clutch is slipping it will usually show heat on the converter cover. The cover will turn blue and or black from the heat. If that's there, the converter is toast.

Second, you can watch live data using Forscan or a real good scan tool. If the converter clutch duty cycle is at 100% and there is still converter slip you have a bad converter. If the duty cycle increase but the slip doesn't fall to zero it is probably a stuck valve.

 

[jschildm]

Thanks for the responses. I'll see if i have time this weekend to pull the inspection cover and try and look at slip and converter clutch duty cycle. Just to confirm, both of these channels will be available with an E4OD? I will also probably start shopping for TC, thanks for the mention of RacerX, I hadn't thought of him yet.

 

[jschildm]

I took some pictures with the inspection cover off. The TC is rusty so I am not sure if that means it has been hot and then burnt the paint off, or if it hasn't been hot enough discolor. I drove the truck a little and the TC locked up just fine now, it wasn't enough to get up to temp or pulling a trailer or anything. I am also not sure if the black lines in the pictures are cracks or just discolorations.

I tried watching the torque converter clutch channel with Forscan but it never changed from zero. The shift solenoid channels seemed to work, but not that one. I also didn't see a percent slip or RPM slip channel to monitor. I will try looking at the data again and running it little harder to see if it will act up.

 

[Mark Kovalsky]

From what I can see it does not look blued. The factory does not paint the converters, they are just bare steel.