My engine constantly revs to 2k(3k while the engine's cold) when I'm in neutral. I've already replaced the IACv, the gaskets on the manifold and throttle body(as well as the whole I.M.), and the map sensor. My friend, who used to be a tech for honda, says it can't be the TPS for reasons unknown to me. A friend of his told him it could be the fast idle valve, and we're gonna go hose it down w/ some carb cleaner tomorrow and see what happens. I don't fully trust the IACv that i bought used off of ebay, but my friend does have a spare that he says works. If neither the spare IAC or cleaning out the fast idle doesn't work, does anyone have any idea what it could be?

A few notes. After replacing the I.M., it will kind of fix itself every now and then. Sometimes it will stop jumping and settle around 1500. Also, it tends to do the same thing for a little bit when I turn on the A/C.

 

unplug the IACV and the idle should drop & even out. That will tell you if there is an issue with IACV.

 

Is the linkage/cable lubricated?
Can you return it to proper idle manually?-Bob

 

Id guess its the Fast idle thermo valve (FITV) or a vacuum leak.
Put your hand over the throttle body and see if it continues to run, if yes, you have a leak.
Do a search on honda-tech.com All the info you need to fix it is there.

 

have you tried the idle adjustment screw on the side of the throttlebody? its a flat head screw... also look for loose or disconnected hoses, and double check your throttle adjustment cable (the 2 12mm nuts)... another thing is, there is a type of pcv valve with a small tube on it... this has 2 philip head bolts and is bolted on top of your throttlebody and has a piece that hooks to the same place that the throttle cable hooks to... if this valve is bad it will stay open and let too much air in causing a high idle or if its seal is bad it makes it not hold vacuum and gives you high idle as well cuz the air cannot get a vacuum... the best way to fix this is to remove this valve completely and eliminate the hose that goes to it. the only other thing to check would be to look inside your throttlebody and see how clean the it is... cuz if there is some "funk" it wont let the butterfly close all the way. check all the things or have someone look at it for you. then let us know what you find.- Jason