i just recent swap in an lsvtec in my car. its a b18a block with a b16 head, with gsr cams. i did my valve adjustment, set timing to gsr spec, check my iac, my TB is still stock which is an ls. everytime i start my car, The idle would surge between 1000rpm to 2500rpm... and i have a check engine light (obd 1) the code is 41- i think thats is the o2, but i installed a new o2 and still doing the same thing. if anyone has encounter the same problem could u let me know, and the solution to fixing it... ty

 

Bleed the cooling system, make sure there is no air at all. That "should" take care of your idle problem. If not, clean the IAC valve with some carb cleaner. As for the code, did you try resetting the ECU? Leave the battery unhooked for a bit then try again and see if the code goes away.

Colin