idle question

[Cb7_Qc]

what is it in the car that makes the idle go up the 1,5k when its cold outside and the engine is cold? all my cars did that but since i put the new motor in, it doest it like 2 times in a row...i start the car and my idle is 950, then after like 2-3 seconds it goes up to 1,5k and stays like that for a couple seconds, then drops back to regular idle and then right away up again to 1,5k till either hte motor warms up a bit or i start driving...
im not talking here about an up and down idle problem like when u have a vaccum leak or a IACV/EGR problem

[all_accord]

It's the fitv it's there for the car when it's cold to help it warm up faster

[wildBill83]

Yup, check the diaphragm in the fitv. It's the pancake thing on the right of the intake manifold. Otherwise you have an intermittent vacuum leak that seals when warmed up.

[Cb7_Qc]

ok thx guys, will do!