Any dtc's? p1870? Used to see alot of these at the dealership and they always needed a valvebody, espesially 98-02ish...If you caught it early enough you could get it to lock up with the tech2 like your describing because that commands 100% pwm on the solenoid, unlike letting the pcm control the lockup where it starts out at like 50ish pwm (dont quote me on that its been a while) but its alot less than 100%, so you dont "feel" the lockup occur. The steel tcc valve wears the aluminum vb and slowly begins to not "hold" in lockup. I dont know about efi live but in hp tuners you could set the min and max tcc pwm to 100% so it always goes for full lockup, maybe try that and see what happens...this would only be a band aid but might help with diagnosis.

 

LSF-150:
I think you hit the nail on the head! I need a new valve body without a doubt I tryed it tonight set both to 100% and she locked up!

Now I need to find a new valve body! Thank you for saving me some dough!

 

good deal.. glad you got it figured out

 

glad i could help, they make a repair kit for that so you wouldnt have to replace the valvebody, i've never used one but i believe its some kind of reamer and new valve and sleeve, i think they're less than a hundred bucks too...i'm sure someone here has used them, maybe they will chime in

 

this is what I use on every build...eliminates the need for the reamer or any other expenses

4L60E TCC VALVE P1870 CODE FIX 1995-2000 TeckPak USA | eBay

 

Good info! Mine is doing the same thing...

 

100% duty cycle command in your tcc table has the same effect via hp tuners or efi live.