so i've realized when i'm at a light,my car idle's up and it only happens when it rains.
car is auto with 143k.

any ideas on what can cause this?

 

Vacuum leak. Or if you have a CAI your sucking water, Just a small amount not flooding the engine

 

never thought of a vacuum leak.
if it was that..wouldn't i have the same issue even if its not raining?
no CAI btw,not yet

 

I agree u possibly have a vacuum leak. I would also give the throttle body and iacv a cleaning.

 

there was a thread on here where someone else was saying that their idle would go up to whenever they came to a light and it was raining.

Turned out to be a bad coil pack. After like 3 months of issues the car finally threw a CEL for a misfire

 

I could see it being a coil pack also. Have learned very fast they do the damnedest things before they go bad all the way.

As for the vacuum leak only showing up in the rain, water can affect it to a point that the IACV can not compensate for the leak.