Pushing brake pedal hard makes idle drop, bad brake booster ?
#1
Pushing brake pedal hard makes idle drop, bad brake booster ?
I just realized after turning down the idle on the car seems to have made it run alittle smoother but when I come to a stop the cars rpms will drop and practically want to die out sometimes. It all depends on how hard i push that pedal though, the harder i push it the more the car bogs down.
My brakes seem like they are working fine to me but what could be causing my problem ? I would think the brakebooster but I am not sure because my brakes seem to work fine so Im not sure if it is that or what it could be. Maybe its something easy to fix ?
Anyone ever have this problem ? Any ideas ?
My brakes seem like they are working fine to me but what could be causing my problem ? I would think the brakebooster but I am not sure because my brakes seem to work fine so Im not sure if it is that or what it could be. Maybe its something easy to fix ?
Anyone ever have this problem ? Any ideas ?
#3
Originally Posted by bmwrx7man
my man wat up .maybe the dirphram in the brake booster or w/e u spell it
Maybe it could be the brake master cylinder ? I donno
#5
Originally Posted by pimpdaddy7835
This happens to me, but is barely noticeable.
If it's really bad, you might want to replace your BAC Valve or whatever
But like I said, my 7 barely does this and nothings wrong with it
If it's really bad, you might want to replace your BAC Valve or whatever
But like I said, my 7 barely does this and nothings wrong with it
#6
F yo couch!
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try this as a test now before you blow this off try it for real because this is happeneing to my car slowly....ok....start the car let it idle for a while.....now turn on as much electrical stuff as possible (like...everything) does it do it then? if so its your alternator going...or you need a higher output one (and to all the critics your alternator loosing power WILL lower your idle).
....anyway....if not it could possibly be those infamous vaccum leaks....but hey i dont no....just making you think...trying to help
....anyway....if not it could possibly be those infamous vaccum leaks....but hey i dont no....just making you think...trying to help
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#8
Originally Posted by El Nene 7
Inspect the hose that goes off to the UIM , if its bad that could be your problem also oh and does it still have the oem valve
#9
MODERATOR
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no no no...on your stock brake master cylinder theres a 90 degree tubing that comes out , theres a hoses that connects to that 4" on the hose theres a OEM vacumm fitting then i goes back to hose then it routes it way on the firewall along with your brake lines and into your UIM.
I never said emissions related valves
I never said emissions related valves
#11
Cake or Death?
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Originally Posted by helghast7
did you try it? no? ahh well i tryed to help
Easily checked by disabling the brake light switch at the pedal- if the idle still drops then it ain't an electrical problem.
Much more likely to be a vacuum leak anyway.
#12
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The only way the alternator could be involved in this scenario is if the draw from the brake lights is excessive.
Easily checked by disabling the brake light switch at the pedal- if the idle still drops then it ain't an electrical problem.
Much more likely to be a vacuum leak anyway.
Easily checked by disabling the brake light switch at the pedal- if the idle still drops then it ain't an electrical problem.
Much more likely to be a vacuum leak anyway.
Get a vacuum tester and test the booster but you will probably find that its good and you will probably need to raise the idle to around 800-900 rpm. This is what the BACV is good for. Removing it serves no point. I removed mine 5 years ago and have had my idle around 850-900 without problems. Idle does drop when hitting the brakes but that is from the lights in the rear and some from the booster. Goes down to about 700-750rpm.
The engine has very little power (HP/Torque) at lower rpms such as 750rpm. So it takes very little for the engine to react negatively to something.
When you are pressing on the brakes or pumping the brakes, you will be affecting the vacuum in rear of the LIM which will cause the engine to lower or buck around if you are pumping the brakes hard.
If the booster was leaking, then without even pressing the brakes the engine would essentially have a vacuum leak
A quick easy way of testing the booster for leaks is to turn the engine off, depress the brake pedal many times and pedal should get very hard and should be hard the whole time you press on the pedal. The pedal should never slowly go to the floor.
try this as a test now before you blow this off try it for real because this is happeneing to my car slowly....ok....start the car let it idle for a while.....now turn on as much electrical stuff as possible (like...everything) does it do it then? if so its your alternator going...or you need a higher output one (and to all the critics your alternator loosing power WILL lower your idle).
Read this thread. It tells you how to test your alternator among other items
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/battery-drain-issue-628141/
Maybe it could be the brake master cylinder ? I donno
Last edited by RotaMan99; 03-21-07 at 08:01 AM.
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