Hi,

after finishing my swap I noticed that when i depressed my brake pedal at idle my revs would surge up to about 1200rpm then drop to 200rpm or less.

after some searching i was told to block up the brake booster line and push the brake pedal, if there was no idle fluctuation then that indicated the booster needed repairing or replacing.

well there was no fluctuation so that should indicate the booster is bad.

just wondering if anyone knows if its going to be the booster that bad for sure or is there a possibility its the MC too?

and also would upgrading the MC and SC to ITR spec ones over my SI spec ones with my standard SI rotors make any difference to my breaking at all?

please help guys as im allways saftey concious about breaks!

 

My car does that. Never though anything of it. The brake booster stores/ uses vacuum. So i just figured when you pump the brakes and put that vacuum to use the valve opens in attempt to get more vacuum. When the valve opens suddenly i would think it would act like a vacuum leak causing the idle to jump up and when you stop depressing the pedal and the valve closes again may cause a slight drop in RPMs while trying to steady