ok, so after searching i found a similar thread but not the info i was looking for. my problem is fairly urgent... driving to work with brakes that dont brake at 85 mph... meh, that could ruin a day pretty quick lol. so about a week ago my brakes started to get soft on me. like real soft. to the point where now in engine braking to slow down on top of flooring the brake pedal. so tonite im parking my car, i press the pedal when the cars running and i can hear a hissing noise whenever i have the pedal down. it stops when i let off, but the the engine shudders a little bit. not enough to stall it, but just enough for it to shake the car a little bit. my friend was saying "master cylinder dawg" but he's a tool and doesnt know the first thing about his own car let alone mine. so my question is what could be the problem be? btw, i was bleeding my brakes and the fluid in the MC was BLACK, as black as death's fetid soul.

 

https://honda-tech.com/zerothread?id=2279595
do the test first and narrow it down go from there.

 

sounds like a mixture of the brake booster and master cylinder.

When a brake booster goes bad it sounds like air is leaking or a whistling when you push the peddle.

A soft peddle that sinks to the floor is a bad master cylinder.

I would replace both if them and see how it works.

If it doesent fix the problem jsut simple return the bb/mc.

but that does like your problem.

 

I think you could start with just the master cylinder.

 

i had the same problem, come to find out one of my rear drums had a leak that was slowing getting real bad... if your losing any brake fluid maybe check there... none the less nothing wrong with a new master cylinder purchase

 

ok, got everything apart and back together. wound up replacing the mastercylinder and booster. the mc was leaking and the booster had a hole in the diaphragm so i was like eff it all ill replace em both. if only there was an upgrade for the MC and booster.