2014 - 2015 Corvette: GM TechLink: Rough Idle or Vibration

Subject:   Rough Idle or Vibration
Model and Year:  2014 - 2015 Corvette
Source:  GM TechLink
Page Number:  NA
Date:  October 8, 2014

On some 2014 - 2015 Corvette, Silverado, Sierra and 2015 Tahoe, Suburban, Yukon, Yukon XL and Escalade models equipped with the 4.3L, 5.3L or 6.2L engine (RPOs L83, L86, LT1, LV3), there may be a condition of a rough idle or a vibration at idle in gear. There will not be any DTCs with this condition.

To correct the vibration, perform the following motor mount alignment procedure.

1. Loosen the engine mount bolts at the frame attachment points. (Fig. 15)

Fig 15

2. Lift the engine slightly to take the load off the mounts.

3. Use a pry bar to push the mount outboard as far as possible (about 1–1.5 mm) (Fig. 16, left engine mount; Fig. 17, right engine mount); torque the bolts while pushing the mount outboard.

Fig 16

Fig 17

4. Tighten the center/upper bolt first, then front, then rear (Fig. 18). Complete this procedure for both left and right mounts.

Fig 18

5. Lower the engine.

The vehicle may need to be driven for some time to confirm the condition has been eliminated.

- Thanks to Richard Renshaw