idle spd. drops to 1krmp or 900rmp when start warm, constant. And there is a very slight vibration at this point(can be noticed when touching the engine lid but not noticeable when seating).

looked at some posts, some said a good idle should never drop below 1k rmp, some just claimed 800 is good tho. Is my a slightly rough one?

Thanks guys!

 

Try writing in a more clear and concise manner - you'll probably get a faster response.

But my '8 has a slight vibration at idle also, but idles in neutral at ~750rpm. If you can't notice the vibration at all while you're sitting in the car, then you most likely have nothing to worry about. My vibration shakes my shifter enough to lightly vibrate my hand when it's resting on it.

If you're concerned, you can clean you MAF and IAT with electronic contact cleaner (there's a DIY for it) which takes about five minutes. This has helped other users with idle problems and at the very least won't be detrimental to your vehicle. If it persists/gets worse, get your motor mounts checked.

 

is your AC on?

 

According to my phone, my car consistently idles between 800-860 rpm's when warm with the A/C on, on occasion it'll bump up to about 1k rpms with my headlamps/a.c./ and radio on. Just the heavier demand on the electrical system, if your A/C is in fact on...while this is happening.

 

It should idle 850 ish....won't idle at 1K with a stock tune in the ECU unless it is cold still

 

750 I believe is what it is supposed to idle at. Do a Search for "Congratulations, you got an 8" Has some solutions for the rough idle problem, its common.