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Discussion Starter #1 (Edited)
I've had this issue for the few months I've owned the car now... but I've begun to notice it more frequently lately. Never had this issue on my first genesis (2010 track model). Car starts fine, shifts into gear fine, and drives fine.

When I am driving down the road and put the car in neutral and coast... the engine will rev up to roughly 2k RPMs and either sit there (without pushing on the gas pedal) or fall down a "normal neutral rpm level" and then repeat the cycle... rev to ~2k, drop down, rev to ~2k, drop down... and it keeps going. When I then decelerate to the point where I am going to stop... the revs will climb to the 2k range and hang there until the car is essentially stopped... then the RPMs will drop down where they should have been the entire time... and then no issues at a dead stop.

Once I then start driving again... it will keep repeating these processes. No check engine lights are on.

2016 3.8L ultimate stick shift.
CAI, short shifter, ark grip catback exhaust

any ideas?
 

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Discussion Starter #3
Check engine light actually came on this morning on my way to work. Stopped at dealership after... read as:

P0507 air idle RPM control...

They will pick up my car on Monday to look at it closer. They immediately mentioned the AEM CAI I have as well.

Anything I can do at home to fix this?
 

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I'd rather do it myself
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The CAI will not do this, they are looking for excuses. I got this code on my 2L this summer with the idle speed going high. I just had to clean the throttle body with some spray cleaner.
 

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Discussion Starter #5
Fantastic. I'm actually in the middle of taking a look at the throttle body as well. Going to try that first. Thank you. I'll keep this thread posted for further reference.
 

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It's the THROTTLE BODY!

Clean your Throttle Body!
I had the same issue. Did an inspection and found out that the Throttle Body was covered in oil.
The remedy/solution to this is to install a catch can, that way you can keep the oil out of your throttle body.
To clean the Throttle Body, Disconnect the Air filter and hose. All you need is a Throttle Body cleaner (I used Toyota's TB cleaner, since I used to work at Toyota as a Tech).
You have two options to clean the TB.
1) Turn on the car power only (No engine running) place something heavy on the gas pedal, and your butterfly inside the TB should be at WOT.
2) Disconnect the Positive Wire on your battery, Disconnect the Air filter and hose, Remove the TB (Make sure you replace the TB gasket if you have excessive miles) and clean the inside of your TB.

I have a 2015 Genesis Coupe, Cleaning the TB solved my issue. I was having the same exact issue. Just make sure you invest into a catch can!
 

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Discussion Starter #7
I wanted to update this thread. I have cleaned the throttle body probably 3-4 times now since this issue started... and I only have about 44k miles on the car. The issue comes on sporadically. Lately, however, I have noticed that if I keep the "auto climate control" ON, the rev issue does not occur. Once I turn the climate control OFF, the issue returns with auto-revving, etc. I just cleaned the throttle body maybe 2-3 weeks ago?

Any ideas what this could be now?? No new mods to the car. No accidents. Only mechanical work in the interim has been oil changes, essentially.
 
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