i have a 91 civic si and put a b16a and one day when driving, my brake pedal got stiff. now, when i push the brakes, its stiff and my idle jumps up to 2k and cant stop how i used to. any help would be highly appreciated. thanks for your time.

 

Check your brake booster?

 

 

You need a brake booster. When the brake booster goes bad, it leaks and lets the vaccum in and makes the car rev higher, cause a brake booster works off of a vaccum from the engine. So if its leaking vaccum it wont pull the diaphram which makes the pedal very very hard to push.

Just get a new brake booster and you will be good.

Another thing when you get in the car start it up and push the brake, you should hear a hissing, leaking air sound.

 

blow through the hose with the check valve
should let air through one way and not the other

 

have a simlair problem but the pedal feel is reverse. I have a hard pedal with engine off and a softer pedal with engine on. Thanks a lot tyson! the testing procidure should prove most usefull!

 

do what tyson suggested. check everything and if the worst comes, just change your booster. You got options, so do a lil searching. Good luck.