Hey I have a 2019 Kia optima lx 131k miles, I noticed while in park my rpm idle down slightly ever 4-5 secs. I changed all my spark plugs, PCV valve, cleaned my mass air flower sensor. Any ideas what might be causing it?
is it the ac compressor kicking in?
Yea AC is on and on recirculate
Is there a vacuum leak somewhere? Sometimes the computer tries to "chase" the idle speed higher and lower because of a vacuum leak.
I haven't checked for vacuum leaks, any suggestions or ways to figure out how to locate them?
It appears you already found your problem. Turn off the AC and see what it does. If it stays put, you found your answer. The computer cycles the AC on and off to not freeze up the evaporator.
Yea I Turned the AC off n while it's idling it dips smallll bit every 3-4 secs
I haven't checked for vacuum leaks, any suggestions or ways to figure out how to locate them?
If you search youtube you'll find dozens of videos with methods for finding vacuum leaks.
https://www.youtube.com/watch?v=9CPqbaSgcok
Thank you, I'm going to try it in the morning
I’ve had 2 vehicles with a vacuum leak in the same spot. Check the ribbed hose that goes between air filter box and throttle body. Vacuum leak can happen other places too, but I would start with thorough examination of that ribbed hose
@Mark-Snodgrass please don't recommend a solution in the comments. There's a text box below titled "Your Answer", your response goes in that location. Thanks.
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