My shift points are not stock (gears and tires dictate at a minimum some change) but that shouldn't really make a difference (I wouldn't think). My "low throttle" shifts are set to ensure the engine never falls below 1200RPM.

I do have the converter set where it "could" lock up in 2nd but that happens at a MPH AFTER it SHOULD have gone to 3rd (for instance IF I held it in 2nd gear, the converter would eventually lock). The shift MPH vs Converter Lockup MPH are basically the same values with 5MPH added for the converter table.

It has always shifted "hard" from day one when I drove it off the lot new. I didn't think anything of it since it was new and I just assumed "its a truck....I'll tone down the shifts when I get HPTuners on it".

Its nice to know I'm not the only person who is totally stumped.

 

Well I found the issue (finally). When I swapped in the LS1 manifold on a few weeks ago, I had to install a 90degree in the intake tube routing to fit everything correctly. Since then I have been playing with the MAF table to compensate for lean LTrims. The VE table did not need any major modification (1%-2% in places) but I had to skew the MAF table by as much as 15%-20%.

Despite trying to adjust the shift pressure tables, that far of a skew on the MAF still messed up the tranny workings.

I found all this out by accident today. In attempt to come at my lean LTrim issue from a different perspective, I set the MAF table back to stock and started skewing the Injector table to richen up. All of a sudden, the tranny shifts nice! Still sharp and fast on WOT shifts, but "normal" driving shifts are almost un-noticeable.

It looks like up to about 5%-10% either direct on the MAF table seems to be the "limit" of adjustment before the automatic tranny starts to "act up".

I still need to look into WHY the MAF is so "lean". Since the only thing that "changed" is the addition of the 90degree bend, my guess is the air current going into the MAF is being routed "around" the sensor elements. Someone on LS1Tech pointed to possibly re-clocking the MAF orientation in the air stream to see if that changed anything. I'm also going to grab an "un-modded" MAF and see if the "air straightener" grid helps in this location.

Lesson Learned: Leave the MAF table alone if at all possible.

 

if anything happens to the MAF it will enable max line pressure... you can take care of that under the transmission diagnostics, i havent messed with HPT much so i cant tell you exactly where the parameter is at.

 

HPTuners does not seem to have a table under "trans diagnostics" to adjust MAF failure line pressure. The only "max line pressure" table I can find is the standard "max line pressure" under the tranny shift properties section.

 

Turn off (set to no) Codes P0101,P0102 and P0103.

In EFILive they are in 3 sections under Transmission Diagnostics:

1.) Transmission DTC Fault Max Pressure Enablers
2.) Transmission Failsafe Enablers
3.) Transmission DTC Fault Pressure Modifiers

That might help you find them in HPT. I had to set then to No in all three sections or my part throttle shifts 1 -> 2 were very hard and abrupt. So much so I had to replace my flywheel, spacer and bolts (>$500) because the holes elongated due to the hammering from the shifts.