LS SWAP 4l60e problems

[Crash_OK]

I am working on finishing up my LS swap http://67-72chevytrucks.com/vboard/s...d.php?t=629115. I still have a few items left to complete. I have put over 600 miles on the vehicle with very few issues. However, I do have two transmission (4l60e) related issues I am hoping some of you can help me with. I am not sure the issues are related so I will describe them separately. I don’t know much about this transmission, I purchased off of craigslist from a guy that claimed he only pulled it out to replace it with a 4l80e. I don’t have much in it, and when I pulled the pan everything looked pretty good, so I changed the filter, installed new seals, and bolted it to the L33. Other than the two problems I am about to describe the transmission has been great. Shifts nice and on time doing normal driving and shifts firm and at the right rpm when you get into it.

First problem is around the TCC. It almost seems like it is operating backwards. When I am on the highway at 73 mph (cruise on), the engine is turning ~2390 rpm.. when I hit a hill or add a little load to the engine, the RPM drops to ~2260 and stays in that area until the load drops. I have a Scan Gauge 2 that shows load.. at 70 load (I assume %) is where the trigger point seems to be. To me it appears that the TCC is working backwards. When I am at light loads the TCC is NOT engaged, and when I add load it is. Anyone have any ideas? Have you seen this before? I have not be able to find this problem in any of my research. The one thing I have seen is that engine misfire can cause the TCC lockup to not work. I wonder if there is any chance if that I am have engine misfire at light loads and not at heavier loads. Seems farfetched to me…

Second problem is around shift points when transmission has been on the highway for a couple of hours. I believe it is heat related. I can drive a couple of hours in the cool part of the morning and not see the problem. However in the heat of the day (95F +) it shows up. While I am traveling on the highway the transmission shows no problems other than problem one above. However, once I come down to a stop or really slow speeds the problem appears. The transmission will not shift from 1st to 2nd or 2nd to 3rd with running the rpms up to ~3500 rpm (Don’t know about 3rd to 4th). There does not appear to be any slippage. The truck will push you back in your seat. And when it shifts it shifts like it would at WOT, firm. After driving in the city for a little while the problem disappears. I can also let it set for a little bit and we are back to normal. Thoughts?

I could swap the transmission out if I need to.. but 99% of the time everything seems to be right.

Thanks for your help.