C8 Issue with DCT/Accelerating in manual mode
Thread Starter
Cruising
Joined: Apr 2023
Posts: 14
Likes: 9
C8 Issue with DCT/Accelerating in manual mode
Hello all,
Just picked up my new C8 corvette, & after breaking in, I had an issue occur where while i'm in a high gear, say, 4th, 5th or 6th, in manual mode, if i lightly push into the throttle, there is a "thud" almost like hitting a speed bump before the car starts to go. If i quickly depress the pedal, there is no thud. If I apply light throttle, then push down, there is no thud. It only happens when im in manual mode, and slowly push from no throttle down to full throttle. It happens right after the engine begins to respond to the throttle input
In addition, while playing around with the modes and paddle shifters, I had the engine light come on and the codes were P2854E and P0700. After starting the next morning, the engine light was gone, but after again messing around with the modes and paddles, the engine light returned. I fear that the throttle "thud" issue is more mechanical and unrelated to the engine light & codes, so I am wondering if anybody else experiences a "thud" shortly after slowly depressing the throttle in a higher gear, i.e. 5th or 6th at low rpm (2500-3000)
Thanks alot!
Sal
Just picked up my new C8 corvette, & after breaking in, I had an issue occur where while i'm in a high gear, say, 4th, 5th or 6th, in manual mode, if i lightly push into the throttle, there is a "thud" almost like hitting a speed bump before the car starts to go. If i quickly depress the pedal, there is no thud. If I apply light throttle, then push down, there is no thud. It only happens when im in manual mode, and slowly push from no throttle down to full throttle. It happens right after the engine begins to respond to the throttle input
In addition, while playing around with the modes and paddle shifters, I had the engine light come on and the codes were P2854E and P0700. After starting the next morning, the engine light was gone, but after again messing around with the modes and paddles, the engine light returned. I fear that the throttle "thud" issue is more mechanical and unrelated to the engine light & codes, so I am wondering if anybody else experiences a "thud" shortly after slowly depressing the throttle in a higher gear, i.e. 5th or 6th at low rpm (2500-3000)
Thanks alot!
Sal
Race Director
Joined: Mar 2007
Posts: 11,355
Likes: 8,509
I have a version of the 2020 Service Manual. I believe that P0700 is just a code indicating that a request to illuminated the CEL (the check engine light) on the DIC was made. I could not find P2854E, but I did find P2854. I do not know if its the same, related, or what. That code is a transmission code, and the descriptor is "Clutch 2 Pressure Discharge Performance". Its triggered by one of the Transmission Fluid Pressure sensors. It sound as if it might affect the way the clutch operates, so could be consistent with a thud or thunk. One thing it says is "Discuss with the customer about the driving conditions when the concern occurred A DTC may set depending on certain driving conditions and would not require a component replacement." I did not see where it said anything more about that. If had the situation you described, and if that code came back, I would be headed for the dealer.
Pro
Joined: Aug 2011
Posts: 562
Likes: 290
From: Philly Suburbs PA
My car had 3300 miles on it when I bought it so I did not need to break it in. I don’t shift into high gears at such low rpm’s and if it is not behaving like that when you give it more throttle you might just be shifting at to low an rpm for those higher gears. If you drive in auto mode and see when the car shifts itself it might help you see where the cars computers shift. I don’t know how much experience you have with a DCT but I would would not shift a manual car into 6th gear at 2500 rpm I have a feeling certain ones would react in a similar way.
Race Director
Joined: Mar 2010
Posts: 15,996
Likes: 823
Hello all,
Just picked up my new C8 corvette, & after breaking in, I had an issue occur where while i'm in a high gear, say, 4th, 5th or 6th, in manual mode, if i lightly push into the throttle, there is a "thud" almost like hitting a speed bump before the car starts to go. If i quickly depress the pedal, there is no thud. If I apply light throttle, then push down, there is no thud. It only happens when im in manual mode, and slowly push from no throttle down to full throttle. It happens right after the engine begins to respond to the throttle input
In addition, while playing around with the modes and paddle shifters, I had the engine light come on and the codes were P2854E and P0700. After starting the next morning, the engine light was gone, but after again messing around with the modes and paddles, the engine light returned. I fear that the throttle "thud" issue is more mechanical and unrelated to the engine light & codes, so I am wondering if anybody else experiences a "thud" shortly after slowly depressing the throttle in a higher gear, i.e. 5th or 6th at low rpm (2500-3000)
Thanks alot!
Sal
Just picked up my new C8 corvette, & after breaking in, I had an issue occur where while i'm in a high gear, say, 4th, 5th or 6th, in manual mode, if i lightly push into the throttle, there is a "thud" almost like hitting a speed bump before the car starts to go. If i quickly depress the pedal, there is no thud. If I apply light throttle, then push down, there is no thud. It only happens when im in manual mode, and slowly push from no throttle down to full throttle. It happens right after the engine begins to respond to the throttle input
In addition, while playing around with the modes and paddle shifters, I had the engine light come on and the codes were P2854E and P0700. After starting the next morning, the engine light was gone, but after again messing around with the modes and paddles, the engine light returned. I fear that the throttle "thud" issue is more mechanical and unrelated to the engine light & codes, so I am wondering if anybody else experiences a "thud" shortly after slowly depressing the throttle in a higher gear, i.e. 5th or 6th at low rpm (2500-3000)
Thanks alot!
Sal
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