New owner of 2015 3.8 Ultimate - Idle issues

[Topspin]

Recently purchased a 2015 3.8 with 26,000 miles. Absolutely love the car except the idle issue I'm having.

While the car is in P, the car seems to idle at around 570-600 with no vibrations whatsoever, even with the AC running. The problem occurs while in D. The idle settles at right around 500-520 (is this the normal range?) and I can feel minor vibrations coming from the chassis/under the seats.

It becomes more pronounced when the AC is running and I could see the rpm drop to 490-495 sometimes for a split second when stopped at a red light.

From what I've read here on the forums, possible causes include:
1. Electric fan weights being off
2. AC condenser problem
3. Engine mounts

Any thoughts or advice?

 

[carguy75]

Probably the fuel you are using. Regular fuel creates a lot carbon which causes the engine to run rough over time. You may need to use some fuel addictive like Techron to clean out your fuel injectors.

Premium fuel has more detergent and usually helps with carbon buildup in the combustion chamber that usually coats fuel injector tips.

 

[Andyj]

Run the tank down to under a quarter and fill it with top tier premium 91 octane gas. Add a bottle of techron and drive it like you stole it for a while. Should purr like a kitten.

 

[Topspin]

I am only on my 2nd tank of gas. I did use a techron treatment on the second fill but didn't notice a difference so I'll try it a few more times with higher octane gas.

But is it normal to be idling at 500 in drive? Is there a way to raise it to 600-650 through the dealer or via a 3rd party reprogramming?

 

[skipgen]

My 5.0 idles @ 500 rpm when warmed up. I think it's too low but it's prob an irritating fuel saving measure....

 

[Markymark]

My 5.0 idles @ 500 rpm when warmed up. I think it's too low but it's prob an irritating fuel saving measure....

And it purrs like a cat, doesn’t it? I love this car and the 5.0 engine. I took it out and it just feels so luxurious. I occasionally see older Korean men looking on in approval.