In idle it shakes so hard my teeth hurt.

[Donyer]

Hey, 2014 fiesta with 76k miles. Ive had the car since 2015 and only recently has it started violently shaking while in idle, especially on startup. It doesn't matter if the AC is on or off but its certainly worse with it on. After driving for a bit, it sometimes goes away but sometimes will not. As soon as I give any preasure on the accelerator, the shaking disappears. According to my AP, my boost is in the normal range so i don't think there's leaks? No codes are present either. It doesn't feel like it is going to stall and idles at ~850-1000rpm

 

[Jabbit]

Check your motor mounts. Also does clutch in/out have any impact on the feeling?

 

[gtx3076]

Check your engine mounts.

 

[Donyer]

Its a cobb rmm that Ive had in since 2016. Clutch in will very slightly let up the level of vibration but only slightly

 

[gtx3076]

Its a cobb rmm that Ive had in since 2016. Clutch in will very slightly let up the level of vibration but only slightly

Check ALL of your mounts.

Plus those polyurethane bushings deteriorate with heat. 2016 was a long time ago now.

 

[dhminer]

High likelihood it’s mount related. As others have said the poly bushings in RMMs deteriorate fast being next to the hot af downpipe. Cpe uses rubber for this exact reason. Also check the upper mount on passenger side. The bolt is known to shear. I haven’t seen many trans mount problems reported, so I’d check that one last if you don’t find a problem with the RMM or passenger side mount.