Not Enough Vaccuum
10-15-2006, 11:34 PM
#1
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Not Enough Vaccuum Im having some problems guys, i thought my master cylinder was out on my car, cause when i go to brakes hard, the pedal would get hard and it wouldnt stop, so i had the master cylinder changed and its still doing it..Now im thinking maybe im not pulling enough vaccuum and thats why its causing it to do that...what do you guys think?
10-16-2006, 01:26 AM
#2
Do you have a baby cam, or a "baby" cam? I dont see any mods listed that should cause vaccuum to go so low at idle that you loose all braking ability. Have you checked for any hose leaks, manifold leaks ect?
If every thing is fine you could try bumping your idle up to help with braking.
If every thing is fine you could try bumping your idle up to help with braking.
10-16-2006, 07:39 AM
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What kPa do you see from the map at idle? I'm running a decent cam (232/238) and see roughly 58~62kPa at idle. No vacuum issues here. Brakes work fine and the HVAC operates properly.
10-16-2006, 10:05 AM
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Should be a checkball in the booster line that lets the
booster accumulate some vacuum from better points
so you have some reserve. If this bleeds too badly then
you might have a weak boost. Or maybe this is just old
school and no longer this way?
Might pull the hose from the vac booster and be sure it's
pulling vacuum there (75kPa MAP should still be ~ 4PSI
vacuum) and not fallen off the back of the manifold.
If you prop up the RPM on a coast-down and brake, get
the vacuum up, is brake function improved?
booster accumulate some vacuum from better points
so you have some reserve. If this bleeds too badly then
you might have a weak boost. Or maybe this is just old
school and no longer this way?
Might pull the hose from the vac booster and be sure it's
pulling vacuum there (75kPa MAP should still be ~ 4PSI
vacuum) and not fallen off the back of the manifold.
If you prop up the RPM on a coast-down and brake, get
the vacuum up, is brake function improved?