Hi guys,

For the last couple weeks to a month my '05 MCS has been making this really strange groaning noise when it hits about 3000 rpm in second and third gear. It goes away at about 4200 rpm, and doesn't happen at all in the other gears.

It doesn't feel like theres any performance loss and it happens whether the AC is on or off. It also does not go away when the car has warmed up. It happens cold or warm.

Has anyone had this issue or does anyone have any idea what it could be?

I don't think it's the supercharger, as I've heard that it makes a very distinct noise more like a rattle. This is definitely a groan or wail. I can post a video later if that is helpful.

Thanks for any suggestions