Engine Hunting a Mega High Idle

[Gman]

Done some searching for other posts and got some answers but mine is doing somthing slightly different.

When first started in the morning the revs shot up to 4k and stayed there and didn\'t drop until i put it in gear and started moving.  On the way home from RS the car was hunting badly when in traffic, jumping between 1000 and 2000 rpm and this was accompanied by a constant hissing noise coming from the top of the engine so i am guessing its a vac pipe?

The cars just been mapped and has had a single turbo conversion and has an Apexi ECU.

Any further ideas would be great!

[Fish]

Sounds like a vacuum pipe has popped off under pressure. Best to cable tie each one.

Fish

[Gman]

Would i have noticed boosed issues with this or is that not always the case?

[Fish]

Not always, but it depends which pipe has come off.

Fish

[DRAGON]

Check for air leaks past the throttle body. A sign of this is high intake temps, because the turbo will be working much harder.
Also check throttle linkage, springs etc.

[bnaellis]

sounds like possible inlet manifold gasket.

[antnicuk]

IIRC, didnt you put a metal gasget in?  these are usually pretty strong

[Gman]

Air temps went up to 64 sitting in traffic when we left, there were about 40 when we were on the move.

I replaced the gasket between the upper and lower manifolds, the noise seemed to be coming from underneath the UIM in the middle but i haven\'t had a good listen and poke around cos i was knackered when i got back.

The throttle cable does seem a bit slack, should the be constant tension when idling?

[antnicuk]

no, if its under tension, it will cause the idle to be higher,  the throttle cable was set up about right,   not too much slack and not too much pull in the butterfly spindle when at W.O.T.
If you can here a hissing sound, it is likely this is causing your problem..

[Gman]

Yeah i think i need to find somewhere in the middle of nowhere to park up and have a listen so i don\'t **** my neighbours off.

[AshRX]

This happened to me mate. All it was, was a sticky throttle body linkage. Take the piping off from the throttle body to intecooler and spray some WD40 in the inlet and all on the linkeages like Ross said. Started back up and kept idle at 1000k. I always carry a can now just in case again  :rollin

[rx7veilside]

idle hunting is a sign of vac leak somewhere..mine has done it a couple of times..if its an apexi it takes a little while after finding the prob for the idle to stabilise