Originally Posted by DA8

Sounds like fuel pumps to me. It has been a long time since I changed mine. That was at 100K, I got 178K now. My theory was that 100K was about all they could get. Since I changed them I've changed out the fuel filter a few times thinking that would prolong the life a bit. But if the fuel filter is not changed out by the original owner (because Audi does not list it as a maintenance item) then I think the back pressure eventually just wears them out. I would change out both of them and don't worry about which one is bad. It does not matter which one is bad, they will both go out eventually anyway. Change them both out and you're good for another 100K. Done. It is a nasty job, you need an organic cartridge respirator. Inside the trunk there is no way to keep the trunk from filling with gas fumes.

Originally Posted by Giovanni Giovino 6.0+6.0TT

Hello JJ,
If all coils, plugs, timing, air and fuel supply are good, you may want to check your CAT's, as you most likely still have your X-pipe in place it will be harder for you to tell exhaust gas pressure at tail pipes, in the link below you will see that Chudlin had removed his X-pipe prior to his issue therefore it was easy for him to feel the difference in pressure between the left and right tailpipes when the issue arose, he had the same as you, misfires, stalling, and not being able to go over a certain RPM, as I said, if all air, fuel, spark, and timing is good, a clogged CAT gives the same symptoms you are experiencing.


https://www.audiworld.com/forums/a8-...oblem-2933532/

Originally Posted by Mister Bally

Just an FYI, I got 275,000 miles out of one of the original pumps and the other is still working fine with over 290,000 miles. 2004 with 4.2 BFM engine.

Originally Posted by JJRDM

Thank you Mister Bally, any insight is much appreciated! and BTW I have read all the info you and Mishar have posted...👌🏼🙏🏼 But I wanted to tell you both about my experience going thru the troubleshooting you mentioned based on your experience and the "Service Manuals or Bentley Manual" I disconnected(unplugged) both pumps(one at a time and the car start and run without stopping) and I did the relays test (disconnecting the one by the passenger side footwell make no difference in the car but when I took out the one by the battery the car didn't even start with the two pumps connected. I found that confusing... what is your opinion Mister Bally? my A8L is 4.2 FSI US 2007 Sport suspension.

Best
JJ