[urq] Brake problem

[ANTHONY ATTARD]

Good morning everyone.I have a question regarding my 1983 URQ.Is it possible to get a hard brake pedal on the 83 URQ with the hydraulic booster (versus a vacuum booster), that is typically available on a modern Audi?I have bled the brakes several times myself and had the system bled by a reputable shop. With the engine off, I do have a hard pedal, but with the engine on, the pedal softens. I can't figure out why.I would a appreciate any suggestion(s) from anyone on the list and I thank you in advance.
Tony:  83 URQ, 2008 A3 S-line.