I have a 1991 940 turbo that I have made into a race car. I took the master cylinder off of the booster so I could run a chain race. The front engine car can't have brakes. I left it off for two weeks and ran two races. When I put the master cylinder back on the ABS light was on. When I mash the brake petal down it wants to make the engine bog down. When I try to drive and mash the brakes feel real hard (no ABS) and bog the engine. I would appreciate any help. Thanks in advance.

 

Well, after such modifications it is pretty hard to guess what might have gotten screwed up.

Is the Power Booster OK? It is vacuum operated from the engine and if it's leaking the vacuum loss will affect the running, and bog down. Running a car without a master cyl., did you bleed the system after you put it back on? If not, the ABS will definitely be inop.