Hi, I have an EG6 Civic with a B16A3 engine. On every cold start, the car revs instantly to about 3000rpm and then drops and idles fine at 1000rpm, and then 800rpm when it's at minimum operating temperature (gauge up to about 1/4 of the way high). I've already disassembled and cleaned the IACV. I did a test with it assembled, but blocked with a piece of cardboard, and the car starts fine, accelerating to about 1000-1200rpm. To my knowledge this should be the normal behavior with a functional IACV. Am I missing something or the IACV is dead/not functioning properly? I'm kind of concerned about it, as the engine is not new/rebuilt and oil pressure may be slow to build up in time (the dummy oil light goes off right away, but that is as useful as nothing the way it works).

 

In addition to the IACV, you have a FITV, fast idle thermo valve. The FITV is most likely your source of issue. Sounds like you didn't know that existed, so I'll just give you that, and I think Google will help you further!

 

Thanks, I'll check out the FITV. I thought the issue was with the IACV because when I blocked it for testing the car was fine, and that led me to completely ignore it. Any specific pointers to what the issue may be?

 

The FITV has a wax element and a plunger that regulates air on cold start. Your throttle body has 2 holes on the inside of it. The bottom one is the FITV. The FITV has a screw you need adjust/tighten from time to time. Most people eliminate it.