i have a 92 prelude with an H23. when the engine is cold, the idle goes up, down, up, down, then once the car is up to running temp, it idles fine. i just bought the car from sacramento area, and i live in carson city, NV. its super cold here, do i need to reset the ecu for elevation, or is something else the problem. if i do need to reset the ecu, how do i do it? anything will help, thank you.

 

to reset ECU, disconnect neg battery terminal for for 5 or more minutes. Your idle problem sounds like a faulty FITV.