05-09-2018, 02:45 PM | #15 | |
Drives: 2018 2ss Join Date: Feb 2018
Location: USA
Posts: 83
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05-09-2018, 04:49 PM | #16 |
Drives: 2010 Camaro 1SS Join Date: Mar 2015
Location: Iowa
Posts: 536
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This is what they are calling it. They said if there was an issue it would throw a code. Because there is no code, they won't do anything
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05-09-2018, 05:08 PM | #17 |
Drives: 2018 2ss Join Date: Feb 2018
Location: USA
Posts: 83
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if the 1-2 shift thing is your issue its pretty common and considered normal. in fact its common on other vehicles as well. the 8 speed rams do similar things as well and its been discussed to death. basic tldr from the ram discussions is its standard operating procedure.
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05-09-2018, 05:15 PM | #18 |
Drives: 2010 Camaro 1SS Join Date: Mar 2015
Location: Iowa
Posts: 536
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It does this and I told them this wasn't my concern. It is between 5, 6, and 7th loosing power before shifting. They said if there was an issue it would throw a code and because there is no code, they won't do anything. i'm going to print this other bulletin and try a different dealership
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05-09-2018, 09:24 PM | #19 |
Drives: 16 Camaro SS, 15 Colorado Join Date: May 2009
Location: Jefferson City, Missouri
Posts: 13,943
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What a joke. You clearly tell them its something else, and they point you at this bulletin and tell you nothing they can (or will) do. I honestly don't understand how they couldn't help you if you were to show them the correct bulletin and tell them this is what you are experiencing.
Also, I'm pretty sure almost nobody gets a code from the shudder...unless maybe they've gone so long that the TC is completely toast.
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05-10-2018, 08:19 AM | #20 |
Drives: Former 2016 Camaro 1LT Join Date: Jan 2017
Location: Naples, FL
Posts: 760
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I did not get a code from the shudder. The dealer was very good in acknowledging the issue and even explained the steps- flush first, drive and see if the issue goes away, second step is to replace the torque converter. But mine is a 2017. They said the shudder issue is common in all the A8's- Camaros, Corvettes, Silverados and Colorados. I would think that GM would have resolved the issue for the 2018's though.........
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05-10-2018, 08:36 AM | #21 | |
Drives: 18 zl1 Join Date: Aug 2017
Location: central alabama
Posts: 935
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05-10-2018, 09:47 AM | #22 | |
Drives: Sold it Join Date: Nov 2017
Location: US
Posts: 126
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05-10-2018, 09:57 AM | #23 | |
Drives: 2018 2ss Join Date: Feb 2018
Location: USA
Posts: 83
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if you have the TC issue that everyone talks about it should be happening in other gears as well even on the highway at higher speeds. if you can reliably replicate your symptoms it will make it easier to tell the dealer exactly whats wrong and how they need to replicate the issue so you can get it fixed. |
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05-10-2018, 10:39 AM | #24 |
Drives: Sold it Join Date: Nov 2017
Location: US
Posts: 126
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Why I think the programmed slip tables are causing this
I'm going to go out on a limb to postulate "how" I think the programmed slip
tables are causing this: You accelerate to 30 from a stop then ease up on the gas to maintain 30. The A8 floats up to a high gear like 7 when it feels no load. 5 seconds later you want to slowly speed up to 40. (The car says "D" so you don't know the gear it is in) The A8 should instantly downshift from 7 as soon as I apply gas at 30. (because the load of trying to accelerate from 30 in gear 7 is too high) But it seems like it remains in that high gear and labors, shudders, and transmission slips as it tries to maintain that high gear. I am thinking that the programmed slip tables allow the transmission to slip when the A8 has you in a high gear (like 7) and you try to gently accelerate from a cruising 30mph. This programmed slip may be just enough prevent the A8 from triggering a downshift from 7 to the much lower gear needed to provide smooth acceleration. This explains for me why this goes away as soon as hit the manual downshift paddle. (Or you can floor the gas to create a huge load to force the downshift) So I am betting that eliminating the slip tables would allow the A8 to downshift more aggressively and avoid the shudder condition completely. My previous automatic cars never labored like this. They stayed with whatever gear was right for the speed and downshifted aggressively whenever the transmission felt a load. The A8 should work this way. |
05-10-2018, 10:46 AM | #25 | |
Drives: 2018 2ss Join Date: Feb 2018
Location: USA
Posts: 83
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05-10-2018, 10:54 AM | #26 | |
Drives: 18 zl1 Join Date: Aug 2017
Location: central alabama
Posts: 935
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when you zero out the slip tables, I believe it locks the high pressure pump on all the time, not allowing the converter to slip. It's a possibility that improper fluid, such as mentioned by Al, accentuated this, and possibly even accelerated the failure of the paper friction surface of the torque converter clutch plate. Also from my understanding, once that happens, everything afterwards, other than replacement, is just a bandaid. If anyone has better info, or wants to correct me, feel free to. |
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05-10-2018, 11:11 AM | #27 | |
Drives: Sold it Join Date: Nov 2017
Location: US
Posts: 126
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is a defect in the transmission design. It's basically telling the consumer you can't drive your car gently in traffic but instead you need to go heavy on the gas to avoid having the car shake, rumble, and make bad noises. It's ludicrous to accept this as ok when other cars aren't like this. In city traffic you want to drive easy to avoid getting into an accident. The problem is that the A8 is not downshifting when it should be. I thought AFM was only about turning off 2/4 cylinders to save fuel. If AFM is also causing the A8 to put the car in gear 6 or 7 during low cruising rates of speed like 30 mph I could buy that. But its an absolute defect if the A8 cannot downshift immediately when you accelerate. I will try the tests you wrote earlier see what I notice. Thanks.. |
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05-10-2018, 11:29 AM | #28 | |
Drives: Sold it Join Date: Nov 2017
Location: US
Posts: 126
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postulate why the hell the A8 isn't downshifting immediately to avoid this condition because in my driving I constantly have hit the downshift paddle twice to pull the car out of the nasty funk that it gets in. The lugging that modru2004 describes happens often for me. This is the car laboring and bogging down. I can reproduce this every day. The single shuddering event I had encountered last weekend was on a different scale and included shaking and a much deeper and louder moan like when a garbage disposal gets jammed and can't spin. It's definitely a "this is bad" moment. I'm probably not explaining it well but it's a far more pronounced event and feels like the bogging down event plus more. crosive: I am just wondering if you thought the pump pressure and slip tables have anything to do with the A8 not downshifting when it should? I mention the A8 not downshifting to a lower gear when presented a load when trying to accelerate gradually from 30 in a high gear like 7. Is any of this related? Last edited by T32803; 05-10-2018 at 12:30 PM. |
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