Just put a B20a JDM in my 91 Prelude. Changed over everything but the CYL sensor. Has CAI. Idle speed surges between 1100 and 2100--cold or hot. No vacuum leaks, and Fast Idle Control Valve appears to work normal (did the Honda test). What next? Thanks for any help

Dan

 

did you check the idle air control valve..to check and see if its the fast idle valve you need to take you intake off. inside the throttle body is a small hole cover that up with your finger while its started and if it stops surging then its your fast idle valve...but check those both out...it was my fast idle valve..i just adjusted mines the other day..