idle goes from 1k to 1.5k and back. vacuum leak?

[inh]

i know if you get a really bad vacuum leak it will do this, but i checked all my lines and they arent leaking.. anything else that coudl cause the fluctuation?

[Eyal 951]

IACV could do it.

[SOHC_Rules]

^^^ i concur

[crxtooner]

did you check you high speed air screw if you screw it to the right a half of a turn she should calm down.
crxtooner

[" Low "]

or the fitv... that was the problem on mine, on the tb there is a valve assy, 2 8mm bolts on the firewall side... take that off and there is a plunger inside, screw that down and you are good to go.....

[SOHC_STUDENT]

Mine does this too, Y7 running an S300 P28

It idles at 1000 and then climbs to 1500 and then drops suddenly back to 1000 and repeats.

The ecu threw an IAC (intake air control valve or IACV) error as soon as I plugged it in, assuming because it's expecting a 2 wire IAC where mine is a 3 wire? The idle doesn't effect the driving and I'm planning a swap to ITBs soon so I didn't even worry about it.

Anyway, like the others have said your IACV could be dirty. Try unbolting and cleaning it out with brake cleaner. Depending on what year your car is the IACV is either on the throttle body or the intake manifold. Either way it's cheap/easy thing to start troubleshooting idle probs.

Let us know how it turns out.

[tomatoe]

usually it's the iacv or air in the coolant.

[inh]

it was the IACV> cleaned it with brake cleaner and all is well. thanks guys :D