This is my first post here but I'm hoping someone can help with this. My S8 transmission will start shifting like in S mode by itsef after about 30 minutes of city driving. The shifter stays on "D" but the transmission shifts like it's on "S". I move it to manual mode just to save the gas and my sanity.

Any ideas on this? I did get the recall on the automatic transmission cable but don't know if this is related.

Thanks!

 

Does it start in 1st or 2nd from a stand still when it seems like its in S mode? D always starts and second while in S mode in 1st for better acceleration.

 

I wish that was the case. I can be driving in my neighborhood in automatic 4th with shifter in "D" and the transmission will just decide it needs to be in Sport mode and it will downshift and start running in S mode. The shifter is not moved, but I move it to manual to make it upshift to where it should be. It's almost like a heat issue once it gets to a certain point it just downshifts or possibly a vacuum leak. I don't know how the tiptronic is managed in this car. I was also thinking the transmission fluid might be low but don't know how to check that. With all the covering in the engine compartment you can't find the dip stick. Any idea on that?