I just bought an 02 F150,sc,FX4,4x4. It has a 5.4 and a 4r70w. I have done alot of searching and I get conflicting threads on wether you can do the J-mod to a truck trans or not(Or any links to valvebodies etc.). Also can anyone give me any help on what are good DIY mods??

My truck right now has a lag shift for 3-4 sometimes.

 

Don't know if you really have an issue but the 3 to 4 is going from 3 to overdrive.
This can only happen above about 45 mph road speed and involves some timing.
We would all like to have it shift guickly when the throttle is lifted on a momentary basis or upshift under throttle but that's not the way it works under computer control.
The OD hardware involved won't take a lot of abuse from fast upshifts so the program is written to preserve reasonable life.
It was never designed to do that, only to provide an over gear to reduce engine RPM, wear, and allow the EGR to operate under light throttle applications along with converter lockup function.
The J mod can be done by you with the right parts and instruction.
Shift changes can also be done via PCM shift program changes but you need a programmer and a file to do that.
Good luck.

 

www (dot) tccoa (dot) com/articles/tranny/transmission/index.shtml

 

I have read the TCCOA articles and it has the same conflicting responses.

The lag between shifts jumps up like 400-800rpms. its not just a quick stock like pause!