[V8] To rich and backfiring above 1700 rpm (new thread because its getting to comfusing)

[Fedor Veenhuyzen]

Starting a new thread to sum things up and to make things as clear as possible. I really need your clever minds here!!!

Symtoms:
Good starting (warm and cold)
Good idling
Maybe a bit rich when idling
Up to 1700 rpm (standing and driving) no problems
Above 1700 rpm (standing and driving) it starts to backfire as if its flooding (black smoke)
    In my opinion to much fuel (fuel regulator?) or the ignition not advancing....or..a faulty knocksensor?
The V8 has as long as I have it, been holding in at high rpm's (in S and really putting the paddel to the metal), but it hasn't really been bothering me, as I don't often have to push it that far...but it could be a clue...

When did the problem start?
>From one moment to the other...putting it away, and starting it 30 minutes later.

What have I checked sofar?
All the connections I could reach..all dry and clean.
Vacuum hoses all seem to be ok...
No fuel leaks...
Had the codes pulled...G4 (reference sensor) and G40 (Hall sensor)
    I renewed the G4...made no difference...did not do the G40, cause the dealer said that that one would always come up in connection with the G4.. But I don't trust their advice, or the code pulling for that matter either.
All the fuses are okay.
Fuel plentyfull in the tank.

Please everyone, I hope I've made it clear enough for someone to figure out whats wrong...I am lost and in need of some guidance...I even started to look at www.mobile.de for an A8...and we don't want that do we?? :-)

Fedor
89 V8 Aut