motor stalling

[iwannadie]

ok so when im going say 45mph and get on the brakes quick(not a panic stop, but not a Slow stop either) the motor tries to die out and some times does die. the rpms go Really low if i let the brake off it will usually idle back up and be ok.

im thinking its a vacuum leak some where? is there an easy way to check for that or could it be something else? i just did spark plugs and wires hoping that would help but it didnt.

[Jeeves]

Power Brake Booster

The power brake booster is mounted on the firewall directly behind the master cylinder and, along with the master cylinder, is directly connected with the brake pedal. Its purpose is to amplify the available foot pressure applied to the brake pedal so that the amount of foot pressure required to stop even the largest vehicle is minimal. Power for the booster comes from engine vacuum. The automobile engine produces vacuum as a by-product of normal operation and is freely available for use in powering accessories such as the power brake booster. Vacuum enters the booster through a check valve on the booster. The check valve is connected to the engine with a rubber hose and acts as a one-way valve that allows vacuum to enter the booster but does not let it escape. The booster is an empty shell that is divided into two chambers by a rubber diaphragm. There is a valve in the diaphragm that remains open while your foot is off the brake pedal so that vacuum is allowed to fill both chambers. When you step on the brake pedal, the valve in the diaphragm closes, separating the two chambers and another valve opens to allow air in the chamber on the brake pedal side. This is what provides the power assist. Power boosters are very reliable and cause few problems of their own, however, other things can contribute to a loss of power assist. In order to have power assist, the engine must be running. If the engine stalls or shuts off while you are driving, you will have a small reserve of power assist for two or three pedal applications but, after that, the brakes will be extremely hard to apply and you must put as much pressure as you can to bring the vehicle to a stop.

My guess is that you should verify vacuum lines around it and if that's all fine and dandy, verify it's correct operation.

[iwannadie]

Originally Posted by Jeeves

Power Brake Booster

The power brake booster is mounted on the firewall directly behind the master cylinder and, along with the master cylinder, is directly connected with the brake pedal. Its purpose is to amplify the available foot pressure applied to the brake pedal so that the amount of foot pressure required to stop even the largest vehicle is minimal. Power for the booster comes from engine vacuum. The automobile engine produces vacuum as a by-product of normal operation and is freely available for use in powering accessories such as the power brake booster. Vacuum enters the booster through a check valve on the booster. The check valve is connected to the engine with a rubber hose and acts as a one-way valve that allows vacuum to enter the booster but does not let it escape. The booster is an empty shell that is divided into two chambers by a rubber diaphragm. There is a valve in the diaphragm that remains open while your foot is off the brake pedal so that vacuum is allowed to fill both chambers. When you step on the brake pedal, the valve in the diaphragm closes, separating the two chambers and another valve opens to allow air in the chamber on the brake pedal side. This is what provides the power assist. Power boosters are very reliable and cause few problems of their own, however, other things can contribute to a loss of power assist. In order to have power assist, the engine must be running. If the engine stalls or shuts off while you are driving, you will have a small reserve of power assist for two or three pedal applications but, after that, the brakes will be extremely hard to apply and you must put as much pressure as you can to bring the vehicle to a stop.

My guess is that you should verify vacuum lines around it and if that's all fine and dandy, verify it's correct operation.

how does one verify the vacuum lines? i checked each hose and made sure its secure and not leaking(at least that i can hear or feel) while the motor is at idle. i was considering replacing all the vacuum lines with silicon hoses though just because the old rubber ones are most likely factory originals.

im just not sure how to go about finding a vacuum leak other than hearing it really. ive had a hose come loose and it was very easy to track down the louding hissing sound.

thanks for the booster info, i honestly had no idea what its actual function was or how it worked lol...

[Jeeves]

Originally Posted by iwannadie

how does one verify the vacuum lines? i checked each hose and made sure its secure and not leaking(at least that i can hear or feel) while the motor is at idle. i was considering replacing all the vacuum lines with silicon hoses though just because the old rubber ones are most likely factory originals.

im just not sure how to go about finding a vacuum leak other than hearing it really. ive had a hose come loose and it was very easy to track down the louding hissing sound.

thanks for the booster info, i honestly had no idea what its actual function was or how it worked lol...

Pretty much what you did, is the way to do it. The other thing to do, is take a spray bottle with soapy water in it, and start spraying around seals and gaskets and cracks and hoses.. You're looking for bubbles or hesitation. When running, if you spray and the car hesitates and such, it's a good change there's a leak where you just sprayed. There are also other ways to look for vacuum/boost leaks, might want to hit up google.