Corvettes of Temecula Valley

**Important Edit in body*** The dreaded “Shudder,” AFM and 3LT Trim Leather Dashboard Issues

  • 06/08/2023 4:01 PM
    Reply # 13212858 on 13164634
    Robert Erhardt (Administrator)

    My C7 is a 3lt and I had the leather separation issue. It started on the wrap around shroud and then spread to the top part of the dash. Fortunately my car was still under warranty and Paradise fixed it free. It took a couple of days, but it came out looking brand new.

    P.S. This is one of the reasons I ordered a 2lt in the C8 I have on order.

    Last modified: 06/08/2023 4:05 PM | Robert Erhardt (Administrator)
  • 04/11/2023 7:18 PM
    Message # 13164634

    I apologize in advance for the length of this post but I believe the information posted herein is important enough to justify it.

    Tho the C7 Gen is from 2014-2019 the 2014 is excluded in this post **EDIT**ONLY as it pertains to the shudder and triple flush because the auto is an A6 not an A8. Some, if not all, may be aware of these issues but for those who aren’t read on. The shudder is as if you are running over a rumble strip or RR tracks. This is due to the transmission fluid used in the cars from the 2015 models up to Feb. 01, 2019. Cars produced after that date have the new fluid. Moisture was found to develop in the fluid and at certain speeds a shudder can occur. There is a TSB (Technical Service Bulletin) dated 08-19. TSB 18-NA-355. There are subsequent ones and if interested research them. The dealer performs a triple flush in an attempt to remove all of the old fluid. My 2017 (purchased at Paradise) had it done last July under the TSB at no charge. The shudder disappeared. Many posters in various C7 forums have said they were advised by their dealer to drive 200 miles if it didn’t stop immediately after the flush and if didn’t stop by then the dealer will need to ascertain if it’s the torque converter, torque tube or the transmission.

    AFM (Active Fuel Management):

    This is GM’s system that is utilized to achieve the federally mandated average mpg across the GM fleet. It shuts down half the cylinders in a V8. In fact if you are not accelerating you are in V4. Once acceleration ends it returns to V4. This occurs in any mode even track. In the manual it only occurs in Eco mode. The problem is this shifting from V4 to V8 and back to V4 can, over time, result in damaged lifters. If you don’t have a power train warranty it is going to cost you thousands of dollars to repair/replace.  IMO the few extra MPG you get from driving in V4 isn’t worth the risk of damaged lifters. Note not all C7s are affected but there have been some cars in each year of the run affected. There are 2 ways to keep it in V8 all the time to avoid the possible lifter damage.

    1. Have V4 permanently removed by a tuner. **Note if you have a warranty and do this you will have voided any power train warranties and the dealer will know immediately that you’ve had a tune once they plug in their scan tool into the OBD port. **EDIT**i have read posts on multiple C7 from knowledgeable Ca. posters that if you get a tune it will not pass smog. I don’t know if that refers to HP and exhaust systems tunes only. You should ask your tuner beforehand if tuning out V4 will keep it from passing smog. If it doesn’t and you either don’t have a power train warranty anymore or don’t care if it’s voided then it’s up to you whether you wish to have V4 tuned out**. 

    2. Only use the paddle shifters. This keeps the engine in V8.

    3LT Trim Leather Dashboard:

    The leather used on 3LT trim equipped Corvettes may separate. Tho this issue has not affected all C7 Corvettes there have been cars in every year of the C7 Gen affected. Our 2017 Z51 3LT was last year and we had to have our dashboard replaced. This is normally a $3500 charge by GM. One of the Paradise service mgrs. called GM and was able to have our cost reduced to $1330. Tho we greatly appreciate that our cost should have been zero in our opinion. GM has known of this problem since some of the C6 Gen, the C7 Gen beginning in the 2014 year and it’s even affected some C8s from posts I’ve read on a C8 forum. They’ve never fixed the issue and other than their new car warranty, trim is not a covered.item. There is a product that may help if you decide to close the separation yourself. It’s called Tear Minder, an adhesive. There are how to apply it videos on You Tube. I didn’t learn of this product until after we had paid for our dash replacement unfortunately.

    Disclaimer: I am not a vehicle mechanic or technician. The information I’ve provided is from reading numerous posts on both issues in the 4-5 C7  forums I belong to. Some of those posters have stated they are mechanics/technicians. They have stated they either work at a dealer or independent auto repair shop around the country. I am just posting the information to help other C7 owners. You have to decide if you will do anything to your Corvette concerning these issues. I recommend that you do your own research and decide what’s best for you and your Corvette.

    **EDIT** I sincerely apologize for initially leaving the 2014 out of the AFM discussion. I have corrected that mistake with this edit**

    Last modified: 05/31/2024 4:25 PM | Bill Horwitz

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