My 2000 SI has been shooting a IACV fault (14). Im checking it with a jump wire so i cant get which specific code, PO505(14) is iacv system fault. P1508(14) is iacv circuit fault 1. P1509(14) is iacv circuit fault 2. I cleaned my valve myself and it seemed to idle better but very high like its been,1200 to1450 sometimes,but the CEL just kept coming back within hours so i went ahead and replaced it with a new one from Honda. Now the CEL is shooting again but the idle is smooth when i pull the backup fuse until the CEL comes on then it idles high and drives really bad when warm at about 3000 rpm or so in any gear. It just starts bucking on its on and the throttle is real touchy. Ihave to either give it gas to stop bucking or down shift or upshift to get it away from that window of around 3000rpm which it doesnt like. It will not do this when cold or for a day or so after i pull the back up and reset the CEL. Could my TPS be bad? What about the circuit fault 1 and 2 ? What iss that refering to?

 

Drive your car to AutoZone, where they will use a scan tool to retrieve the specific IACV code. My guess is that it will be P0505. In this case, you probably have an intake air or vacuum leak.

Try this test:

Warm the engine up. Pull off the air intake to expose the throttle body. Put your finger over the lower port inside the throttle body. If the idle speed does not drop, then you probably have a vacuum leak.