Strange idle hunting issue..?

Hi all,

not too long ago I changed out my gearbox, mounts, intake and manifold on my dc2 vti-r as some of you may have read in my build.

ever since then I've had an issue with hunting idle. so here's what happens.

the car cold starts fine, idles fine after cold start exactly at 1k (tuned), seems to be fine for a bit of driving too but as soon as it gets hot in the engine bay (20 mins of driving) everytime i come to a stop it will hunt from 1k-1.5k about 1-4 times, before settling at 1.1k (slightly higher than it should be)

every time i stop and the revs come down, or if i rev the car on the spot it does this. and it seems to hunt for longer at each stop when i've been driving for a longer period of time.

possible causes:

- vacuum leak? i have gone over the vacuum lines, TB, and IM twice with carb cleaner. no leaks.

- air in the cooling system? last time the system was refilled I used the bleeder valve method, even so I've belched the system to let any excess air out. don't think there is any air in there.

- ecu? been reset properly.

- fitv? wound all the way in.

- iacv? worked fine on my old manifold, was litterally unbolted for about 10 secs before being bolted to the new manifold. bolts tight.

- tps? whole throttle body was unbolted and installed on the new manifold in one piece. worked fine before.

So i can't really think of anything else that might cause this. which is why I'm posting. doing all of the above seems to have made it better, but after driving for a while it starts hunting again.

i don't have any performance issues or CELs.

input is appreciated.

Throttle cable set too tight ? The FITV need adjusting out a bit ? Have read a few posts on other forums about this. Might pay to seal the gasket on the IACV and check it's electrical side. Common belief seems to be that it reacts to water temp changes, in fact this has nothing to do with it's operation, it's all ECU controlled the water only prevents it from freezing in cold climates.

already loosened up the throttle cable. no change, i could try using some grey sealant (tiny amount) on the gasket but normally if theres an iacv leaking issue you will hear the idle change when you hit the iacv with the back of a screwdriver. tried this with no effect whatsoever.

in terms of the fitv, it was wound out a little bit before and winding it all the way in seems to have helped i little bit for the first 20-30 mins of driving.

well i guess if no one else has any more ideas, is there a possibility of it being a reaction to the new parts with the old tune? although i've never heard of this happening :/

Have a look through this. There is a section on testing the IACV to make sure it's opening and closing correctly. Don't know if it'll help.
http://ecomodder.com/forum/showthrea...ained-967.html