Reggie6

My 1997 A8 is in limp mode. Reverse works fine, but it is not engaging in lower gears. It has been an excellent car and currently has 318,000 miles with no major issues. Engine is still strong, and looks and drives great until this issue. Transmission Control Module has been replaced so I know that is not it. Any other areas I can try before pulling the transmission?

Y888

Just called them out of curiosity Eriksson Industries
2995$+shipping and installation
Rebuilt with torque converter and fluid(FBG).
Yours would be similar.

hillpc

Had the same thing; it would creep very slowly in Drive with no accelerator pedal input, but as soon as I tried to speed up it would make a loud bang and go into limp mode. I did find a cracked upper valve body, had it welded up by Ericcson, and replaced the pressure regulator valve in hopes that I could avoid pulling the trans (a much bigger job than dropping the pan and valve body), but it was not to be. I had also replaced the F125 switch on the outside of the trans because I couldn't make sense of the resistance readings. I also had a problem where I couldn't get the car back into drive after driving it around in limp mode. I replaced the manual valve, which Nat at Ericcson (very knowledgeable) told me sometimes goes bad from swelling, and that jamming problem went away, but the car was still in limp mode. That thread with sordid details is at https://www.audiworld.com/forums/a8-...drive-2891020/

More info about the codes pulled on trans limp mode and mechanically jammed shifter/cable when warm in 97 A8 quattro

Pulled the trans out and sure enough it was the broken A drum. The trans seems to have been rebuilt before, and I suspect that if it was for the commonly broken A drum, that they simply replaced it with the weak stock unit.

From what I understand, the pressure regulator valve wears a ridge into its bore (I was told especially if driven old-lady style for years). Then when one mashes the throttle, the valve hangs up on the ridge and can't release enough fluid to keep the pressure from going high, which then blows the retaining ring right through the the weak end of the A drum by tearing the last 1/4" of the drum out. I suspect the crack in the valve body also comes from the same thing, but I don't know for sure. There are 2 versions of the stronger A drum available. I bought the one with the alligator retaining ring; a pic is at https://www.audiworld.com/forums/a8-...-ring-2902807/

Hope to get it back together soon. The Audi has had my lift tied up for months now. Neither pulling the trans nor rebuilding it is a job for a beginner.