Hello All,

Looking for some help or advice from the always helpful Forum. I have: 2015 Z06 * A8 * Z07 * Soler TB * Range Disabler * BMS Filter * 8900 miles. Had triple flush done, had flex plate and drive shaft replaced due to rattling. Also has A8 software updated. I have only had this car since last week of February, and I have been taking my time to get to know her. The A8 is so different feeling from the A6 in my 2007 Corvette so I have been doing mostly manual shifting to get used to downshifting this car. Here is what has been happening.

The first bit of strangeness started on 7/22. Manually shifting. Drove the car about 45 minutes on the highway each way to my destination, everything is fine. Close to my home is uphill. Everything is fine until I shift into 4th. Stepping on the gas and the car is not accelerating, actually started losing speed. Downshifted into 3rd and it was fine. Came to an easy right turn, 3rd gear coasting into it at 11mph and my active handling icon flashes quickly. I got to a second uphill part and had the same acceleration problem in 3rd gear this time. After my next left the active icon came on two more times in one blocks time. Also had the car surge and pickup speed for a second while I was braking, and my active icon went on and stayed on till I got to a stop sign. Came on again after making a right at that stop, then surged again for a second.

Monday 7/25 did the same 45 minute trip again. Manually shifting. Down was fine, problems coming home on the highway. At one point I believe I was in 5th, same acceleration stuff happened. Downshifted into 4th (should have upshifted to 6th) and it was ok at that point. I believe I went into auto, but I remember at one point afterwards I was stepping on the gas hard and it wasn’t going the way it should of, then it roared and took off.

The worst was yesterday. Manual shifting. Doing in town running around, car was accelerating ok but had some laggy, rough shifting and a good bang from 2nd into 1st. Going up the same first hill from the 22nd in 3rd gear, no problems. Got to that easy right and the car kind of bogged in 2nd, almost no acceleration then hooked up and accelerated. Continued straight, acceleration problem in 3rd. Got to the next left and came to a complete stop. Start to turn in 1st, the car starts jerking and going rr, rr, rr. I could see the tach jumping and dropping. Car finally hooked up and took off. I honestly didn’t think I was going to get through the intersection. Started up second hill and twice had no acceleration in 4th. On my braking left turn at very low speed (I have to almost stop because of a dip) had active handling icon flash. After that left turn I have two speed bumps. Always take them slow in the same way, sometimes get the active icon. Sometimes not.

I got it home, then went out later and made an appointment at my dealer. Drove in auto and it was fine. Drove back in auto and though I felt a little acceleration problem on the first hill, but I didn’t record so I am not sure.

I should add that I had gotten my PDR going and was able to record all of this, showing the pedal meter going up and the car not accelerating, and the actives and surging. Also I need to ad that the RPMs did not move during all of these dead spots. I first thought trans problems, my service advisor doesn’t think so. Another funny thing is, I never had this acceleration problem until after the dealer changed the flex plate and drive shaft. I am not blaming them in any way, but it is true.

So what do you guys think??? Just to be clear, when I say acceleration problem I mean stepping on the gas, no acceleration no RPM increase. It is not a bogging down, there is nothing until I shift up or down. It doesn’t happen every time, mostly happens on the hills close to home (though did happen on a flat stretch of highway), mostly happens in manual in 3rd-4th gear, started after the driveshaft work. Also I would not say my shifts have been great in either mode. They can be laggy and jerky, and I still get that 2nd to 1st hard downshift bang from time to time. I would gladly share the videos and still shots I took. I am posting one of the worst times going up the first hill. Look at the pedal travel, I should be flying but I am not moving.

ANY help would be greatly appreciated!!!! I am a very competent DIYer, is there anything I should check? Sorry this is so long, but I wanted to add as much detail as I could.

You can see the video here:

 

Gonna need to post a video. At least for me it is hard to understand what exactly is going on for you. If anything just sounds like traction control giving you trouble because you're smashing the pedal while going uphill. Clunky 2-1 is common. My car does it as well, but I can mitigate it by downshifting before the rpms drop too much. Normally the car shifts from 3-1 and I've found awkward going and stopping especially when the transmission is cold can give these clunky shifts. The transmission also tends to shift pretty slow and can be laggy if you're not giving the car much throttle to ensure smooth shifts.

Anyway a video would be much more useful than a picture. The car normally shifts into 4th at ~100mph so stepping on the throttle at 47mph may not give you the acceleration you're expecting. That is all I can garner from the picture.

 

Do you have factory tire sizes on the car?

 

I do. The whole car is stock except for the few mods I mentioned.

 

When driving in a straight line Is your steering wheel turned to one side or the other? If the steering wheel is turned past a certain point the EBCM may interpret the steering sensor signal as indicating the car is turning and could activate the stability control which will cut power in order to control understeer or oversteer.

Bill

 

Bill,
No perfectly straight. I am going to try and get the video up tomorrow.

John L.

 

I started a new, must simpler post here:

https://www.corvetteforum.com/forums...-part-1-a.html