[zzhang855]

Hi guys, this is my first post on this forum, please let me know if I made a mistake posting in the wrong section.

Anyway, I'm currently driving a 2020 M8 GC competition, and recently noticed some shaking once every few seconds when the car is idling with AC off. I took it to the dealership and after some diagnosis, they said it was due to low grade fuels (they had a report from the car indicating that all 5 most recent refuels were low grade). I have always made sure to get premium fuel, so the reading must have been wrong.

From your experiences, can the fact that the car mistakes premium fuel as low grade fuel be somehow related to the rough idling? I'm really worried that the car fails to read the fuel grade correctly due to some issues with the engine.

Thank you all for helping me out!

[Tenac]

That typically isn't from low fuel say octane (grade) but more of bad gas. It happens sometimes stations have issues like water leaks or the standing water in the tanks did not get removed when needed. Try switching up your station and seeing if the problem still exists after a tank or two. Easy way to rule out what they are saying.

[zzhang855]

Originally Posted by Tenac

That typically isn't from low fuel say octane (grade) but more of bad gas. It happens sometimes stations have issues like water leaks or the standing water in the tanks did not get removed when needed. Try switching up your station and seeing if the problem still exists after a tank or two. Easy way to rule out what they are saying.

Thank you for your input! I switched to a different station and sure enough, the car rides a bit smoother now. However, there’s still a bit of slight shaking during idle when AC is off, is this overall considered normal?

[Tenac]

Originally Posted by zzhang855

Thank you for your input! I switched to a different station and sure enough, the car rides a bit smoother now. However, there’s still a bit of slight shaking during idle when AC is off, is this overall considered normal?

It's hard to describe a shake but is it like a hesitation or shimmy?

[zzhang855]

Originally Posted by Tenac

It's hard to describe a shake but is it like a hesitation or shimmy?

It’s a slight shimmy every few seconds or so

[Tenac]

Originally Posted by zzhang855

It’s a slight shimmy every few seconds or so

You don't happen to have access to a scanner I'm guessing? It could be as simple as an injector that's dirty.

[bloozemanAZ]

Originally Posted by Tenac

You don't happen to have access to a scanner I'm guessing? It could be as simple as an injector that's dirty.

Or still working it's way out of the bad gas.