So i have a really annoying idle or startup problem with my 2004 Civic LX. When i start it up in the morning while the engine is cold i don't have any problems, it idles high at about 1200 rpms and settles slowly to about 800 rpms while it reaches operating Temperature. But if i start it up while the engine is hot it first surges to about 1200 rpms and then drops to around 350-400 rpms for a few seconds. After that the Engine idles fine. That being said, i don't have any idle problems on traffic lights or stop signs it's just an annoying behavior when starting it up with an hot engine.

 

Do the Idle Relearn process and clean your IACV and throttle body. Same advice as other site.

 

Haha well this site seemed not to respond at all so i decided to look for another site.