Q70L 3.7 vibration at idle

[kami_sn]

Hi, my 2019 Q70L 3.7 with 33k miles recently have some level of vibration at stop, either neutral or drive, with or without AC. I noticed this started couple of weeks ago but now is more noticeable. I found some G37 owners had similar issue but with no promising solution. One more definitive solution from another forum was to set preset RPM from 650 to 700. I tried that and set mine at 685 but the issue still exists, specifically considering AC idle mode runs about 780-800 rpm and the issue still exists.

Here are few thoughts and conditions I am taking notes to hopefully resolve this issue as it has become very frustrating to deal with it:

1.I cleaned both throttle bosies and performed relearn with autel scan tool.
2. Car idles at 650rpm without AC steadily
3. Since this started from outside has some level of exhaust buffeting noise that didn’t exist before.
4.will be checking engine mounts next.
5. I read in one forum, driveshaft rubber coupling tear was causing vibration in a G37 at idle and after fix, it eliminated the issue.
6. Could this be due to dirty injectors?
7. As you can tell from the mileage I don’t drive the car much, could this be the case of stale gas in the fuel tank. I refuel at half empty all the time. Maybe old gas is accumulating in the tank?


Any input is appreciated!

[Ilya]

No codes?

To me this seems like a misfire or issue with gas as you surmise.

[kami_sn]

No codes. It runs perfect in any other way. Slight vibration has some level of drone from exhaust as well.

[Q70sGuy]

Do you physically see the engine shaking?

I haven’t tried it in this car but if you hold the brakes and put the car in reverse and give it a bit of gas you could probably see if the engine is moving up/down excessively which could indicate a bad engine mount.

I’d also check the service manual to see if this is an electronic controlled engine mount?

[kami_sn]

Brought it back from dealer and they performed injection cleaning which I think it slightly made it better. They confirmed engine mounts are fine. I put the car on a ramp and touched the exhaust pipe after lower cats and the vibration I feel in the exhaust pipe is same as what I feel inside.