When I pump my brakes my idle raises 200 RPM's and then drops when I stop pumping...?
#1
When I pump my brakes my idle raises 200 RPM's and then drops when I stop pumping...?
So yeah, if I'm sitting at a stop and I pump my brakes, my idle will almost instantly rise several hundred RPM's--almost like I'm "pumping" my idle up... As soon as I stop pumping my idle settles back down to normal.
I'm guessing my brake-booster is messed up, since this is the only related component that could have any possible effect on manifold pressure (or whatever).
Anyone ever experienced this, or have any guesses?
I'm guessing my brake-booster is messed up, since this is the only related component that could have any possible effect on manifold pressure (or whatever).
Anyone ever experienced this, or have any guesses?
#2
Pumping the brakes will change the negitive pressure in the intake manifold which could cause your idle to raise or lower. Do you still have the BACV? If so that could raise your idle so your engine doesn't bog down as much.
You can take a vacuum tester to the booster to make sure its not leaking.
You can take a vacuum tester to the booster to make sure its not leaking.
#7
Originally Posted by RxFC3S-13B
How is the Turbo running with the N/A Rotors? Strong? Any issues?
I don't believe the benefit is worth the risk--but the car is pretty fast.
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RE WannaBE
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Surging idle upon braking is in no way shape or form "Normal".... I can't even believe someone would say that is a "normal" symptom. The reason being, as some have said, would be that you probably have a vacuum leak somewhere in connection with your brake booster. Especially because at idle you are in a high state of manifold vacuum. That is why I am guessing your booster has a small leak and when you pump it you are introducing un-metered air into your system, causing idle surge...etc...
hope it helps,
Dave.
hope it helps,
Dave.
#12
STUCK. I got SNOWNED!!!!!
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Originally Posted by eriksseven
So yeah, if I'm sitting at a stop and I pump my brakes, my idle will almost instantly rise several hundred RPM's--almost like I'm "pumping" my idle up... As soon as I stop pumping my idle settles back down to normal.
I'm guessing my brake-booster is messed up, since this is the only related component that could have any possible effect on manifold pressure (or whatever).
Anyone ever experienced this, or have any guesses?
I'm guessing my brake-booster is messed up, since this is the only related component that could have any possible effect on manifold pressure (or whatever).
Anyone ever experienced this, or have any guesses?
try it, seriously.
pump the brakes rapidly several times in anything (that isn't diesel)... the idle will rise several hundred RPM as you're doing it, then DROP like a stone afterwards.
Some cars you can even get to stall on the way down.
#13
Sharp Claws
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there was no mention of surging idle when pumping the brakes, he mentioned that it raised the idle when they are pumped.
the BAC does not really compensate for booster load, the idle difference when pumping the brakes is in fact normal, try it for yourself...
you guys need to quit giving bad advice, i sure wouldn't want to be looking for a ghost problem.
the BAC does not really compensate for booster load, the idle difference when pumping the brakes is in fact normal, try it for yourself...
you guys need to quit giving bad advice, i sure wouldn't want to be looking for a ghost problem.
#17
Engine, Not Motor
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Originally Posted by Karack
there was no mention of surging idle when pumping the brakes, he mentioned that it raised the idle when they are pumped.
the BAC does not really compensate for booster load, the idle difference when pumping the brakes is in fact normal, try it for yourself...
you guys need to quit giving bad advice, i sure wouldn't want to be looking for a ghost problem.
the BAC does not really compensate for booster load, the idle difference when pumping the brakes is in fact normal, try it for yourself...
you guys need to quit giving bad advice, i sure wouldn't want to be looking for a ghost problem.
No harm in cleaning the BAC either way.
#19
RE WannaBE
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"you guys need to quit giving bad advice, i sure wouldn't want to be looking for a ghost problem. " Karak
I obviously didn't read that original post correctly. I thought he was saying he had a definate idle surge and that the previous response was that an idle "surge" was a normal condition. In fact, the drop in idle etc, is normal, as long as it is not a surge, sorry for the flamage, I just read it wrong.
Dave.
I obviously didn't read that original post correctly. I thought he was saying he had a definate idle surge and that the previous response was that an idle "surge" was a normal condition. In fact, the drop in idle etc, is normal, as long as it is not a surge, sorry for the flamage, I just read it wrong.
Dave.
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