Ok here goes... The car is a 94 civic, engine is from a 99 EX i think that's a (d15y8) using a p28 ecu. When the car is cold and worming up it sounds and runs fine but as soon as the temp gets up the idle revs up and down up and down non stop. No CEl code. There is a open line from who ever did she swap that i dont know where it goes. its from the purge valve thing on the fire wall (picture). I dont know what these lines are or where they go.

<a href="http://s706.photobucket.com/albums/ww67/harddrnker/?action=view&current=photo.jpg" target="_blank"><img src="http://i706.photobucket.com/albums/ww67/harddrnker/photo.jpg" border="0" alt="IACV"></a>

I was thinking maybe its the IACV but i dont really know. Any help would be great.

 

It sounds like your Fast idle thermo valve is going out.

 

I am assuming you are referring to the EVAP sensor. This shouldn't affect your idle, unles there is an open vacuum line on the engine.

Your IACV should be bolted to the back of the intake manifold, next to the throttle body. Take it off and clean it out well.

 

This is on the throttle body, on the bottom. I don't think this would cause an idle issue... its only coolant.

 

i have been milling around reading every post i can find on this subject because im going through the same thing. I just can't figure it out, i replaced the iacv valve, fitv valve, fuel filter, spark plugs, cap and rotor, cleaned tb and intake, took it to jiffy got an oil change and the fuel package ( lots of smoke from exhaust, but still did nothing). i have sprayed carb cleaner around my intake looking for a vacumm leak. sprayed water on my wires to see if any sputtering or small shocks were visible.

i swear though when i finally fix it, my car should be running like a champ. oh and i have a 95 civic ex, d16z6. help us people!!! please!! thank you

 

bump, don't make me take this thread over!

is it possible its a fuel pump problem, or a main relay?

 

Might wanna look at your Air temp sensor also.

 

Oh! yes sir it did, on my 92 Dx. Bad FITV = shitty idling.

 

Ok i have the old intake manifold from the stock 94 engine. im gong to see if the IACV is the same and hook it up. I will let you know how it goes. Oh and where is the air temp sensor?

 

the idleing on my car goes up and down slowly or sometimes a bit fast...that could be the IACV correct ?

 

It's on the intake manifold.

 

Ok, so yesterday i started my car outside temp was 53. car idled great for about 15 min. untill it got warm and started doing the crazy up and down idle thing. So this time i turned the car off unpluged the IACV and started the car. Now the car idles perfect, but now thers a CEL. So i take it that my IACV is just no good at all because its been cleaned and the cleaning did nothing.

 

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that hose is supposed to go to the evap purge solenoid and then into the intake manifold. The other one going into the same place should be coming from a fuel line that brings the fuel vapor from the gas tank to be filtered and recycled through the engine. At least on my y8 that's how it was. You might want to plug that open vacuum line since it is not allowing any vacuum in the charcoal canister.