ok guys, i think i understand this correctly, but i just want to be sure. i am looking at an lq4 motor for my 91 formula. can i just get the ecm and harness from any 99-02 f-body and it will work with a tune? the ecm is the same physically, just a matter of what tune you program it with? if i go with a newer engine like 06-07, will that be any difference? thanks,

 

they are not the same.
you need the complete harness and everything it hooks up to.
the ecm box may look the same but it isn't.
its like asking if two computers that have the same box are the same computers and the answer is no.
the ecm monitors lots of factors and you need all those factors hooked up, unless you are going to make a chip that disconnects some - like the smog system.
you will probably find that the connectors going into the box from the harness are different.
get everything at one time - and if you can off the same engine.
and dont let the cut any wires. you want the wires from the block - through the fender area, and into the box itself.
carefullt take every connector off so you can just **** it back on.
and if it goes to something you dont have - get that too.
and take a camera and take lots of pictures so you know where everything goes. and take some tab labels and mark the clip with a number and what you took it off of with the same number and take a picture.
LOTS OF PICTURES - they are digital they are free.

 

You can use the PCM and wiring harness from a 4th gen car with the LQ4, you just have to swap to LS1 coil packs (I think you can repin the ones from the truck iirc). I have a friend who put an LQ4 in a 4th gen and used his harness and PCM on it.

I'm not for sure about the motor year it will work with but it should work with anyone of the LQ4 motors. His motor was out of a 2003 Silverado, he was running of course the LS1 coil packs, a victor jr intake adapted for injectors with a 1000 CFM throttle body instead of a carb but it was all controlled by an LS1 PCM.