Control Unit Software Recall; performance issues?
Thread Starter
Member
Joined: Mar 2020
Posts: 98
Likes: 49
AMG-GT
Control Unit Software Recall; performance issues?
Gents,
The dealer replaced my driveshaft this week and I was told that 2 updates to the Control Unit software were pending. I reluctantly opted for the updates because the car has been performing flawlessly. If it ain't broke, don't fix it!
Within the first few minutes after leaving the dealer I was hearing a fluttering/rattle coming from the exhaust when coasting/decelerating. It sounds like a waffling noise or a leaky exhaust to my untrained ear. Worse, the car feels a little sluggish with the exhaust valves open. In fact, I can actually feel a small difference in acceleration when I switch between open or closed exhaust. I'm also noticing the transmission feels a little clunky with some hard downshifts and an occasional hiccup finding a gear under hard acceleration. I've got several track events on this car and drive it weekly. Never had any issues like this.
I'm not sure it's related to the software updates. The exhaust system and the transmission were removed to facilitate access to the drive shaft. Possibly the exhaust system was damaged, or maybe a gasket was omitted during reassembly?
Has anyone else experienced gremlins after the getting the software updates?
The dealer replaced my driveshaft this week and I was told that 2 updates to the Control Unit software were pending. I reluctantly opted for the updates because the car has been performing flawlessly. If it ain't broke, don't fix it!
Within the first few minutes after leaving the dealer I was hearing a fluttering/rattle coming from the exhaust when coasting/decelerating. It sounds like a waffling noise or a leaky exhaust to my untrained ear. Worse, the car feels a little sluggish with the exhaust valves open. In fact, I can actually feel a small difference in acceleration when I switch between open or closed exhaust. I'm also noticing the transmission feels a little clunky with some hard downshifts and an occasional hiccup finding a gear under hard acceleration. I've got several track events on this car and drive it weekly. Never had any issues like this.
I'm not sure it's related to the software updates. The exhaust system and the transmission were removed to facilitate access to the drive shaft. Possibly the exhaust system was damaged, or maybe a gasket was omitted during reassembly?
Has anyone else experienced gremlins after the getting the software updates?
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Joined: Oct 2020
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From: Arizona
Bentley Continental GT; AMG GT
Hi Propdyn,
A couple of thoughts here.
On the powertrain flashes, when the ECU is flashed, both FTs and transmission learned settings (adaptations) are deleted causing these to need "relearning". These both could be accounting for the feel in acceleration and the transmission shifts. The FTs and the transmissions shifts, based on how you drive the car, should be back within 50/100 miles.
On the fluttering/rattling you're hearing with the exhaust flaps, boy, this is very common with these exhaust motors. I couldn't explain why you're only hearing it coincidental with the service/reflash unless the reflash also did something to the data tables that control the exhaust flaps. There was a recent active thread on this where we discussed the ECU control of the flaps. The fluttering/rattling would be considered a malfunction (as in sticky valves), however, some have had success in getting these warrantied, others have not. Probably good to talk to your service advisor, describe it and see if they will look into it for you.
Good luck with it,
Best,
Acta
A couple of thoughts here.
On the powertrain flashes, when the ECU is flashed, both FTs and transmission learned settings (adaptations) are deleted causing these to need "relearning". These both could be accounting for the feel in acceleration and the transmission shifts. The FTs and the transmissions shifts, based on how you drive the car, should be back within 50/100 miles.
On the fluttering/rattling you're hearing with the exhaust flaps, boy, this is very common with these exhaust motors. I couldn't explain why you're only hearing it coincidental with the service/reflash unless the reflash also did something to the data tables that control the exhaust flaps. There was a recent active thread on this where we discussed the ECU control of the flaps. The fluttering/rattling would be considered a malfunction (as in sticky valves), however, some have had success in getting these warrantied, others have not. Probably good to talk to your service advisor, describe it and see if they will look into it for you.
Good luck with it,
Best,
Acta
Last edited by Acta_Non_Verba; Jul 24, 2022 at 08:11 AM.
Thread Starter
Member
Joined: Mar 2020
Posts: 98
Likes: 49
AMG-GT
Thank you for the prompt response, ANV. I'm returning the car to the dealer this week. I posted in hopes of obtaining information that I can present to help diagnose the issue. Thank you again!
Last edited by PWR2W8; Jul 23, 2022 at 07:07 PM.
