Car sometimes shuts-off when braking.

[graphikg]

I have noticed after my 24v swap, that my car will sometimes shut off when I am braking. It has done this when braking hard and soft. It doesnt do it too often. Maybe once or twice a week. Sometimes, when I brake and stop at a light, my car will r3v almost to 1000rpm and go down to normal, then 1000rpm then normal again and do this in a patterned interval. When doing so, I can feel the brake pedal going slightly down then up, down and up.

This makes me think it is a vaccum leak, and it makes me think it is the one way return valve piece on the brake booster. The interesting this though is the vaccum problem usually happens when I push the brake and clutch at the same time (say for a downshift for instance). What could this be?

There is a hose that comes out of the manifold and into the a plastic girling valve piece which connects to the booster, <-- could it be that this piece is bad? Any insight?

[yert315]

it does sound like the booster vacuum. How do the brakes feel?

[sharky]

hmm, I just started and ran my swap for a minute today for the first time and I had the same kind of idle surge, from 800-2000K and was a very rythmic loop. I didnt think that a brake vacumn line could be a problem and I just finished up my brake system today. Anyone else chime in on this?

[graphikg]

it does sound like the booster vacuum. How do the brakes feel?

They actually feel normal. Great pressure. The only thing is, it may shut off at anytime I push the clutch and brake, who knows when. Then the idling issue of course.

I forgot to mention that the car does push the brake pedal up if I have it pressed down when I turn it off with the key when parked. This means the pressure escapes to the booster when I turn it off, forcing the pedal up.

All I am afraid of is having the turn off while turning, then having the steering wheel lock as a result and uncontrollably slammig into something. The pressure is nil when the car is off. Very dangerous!

[yert315]

replace the valve, they're pretty cheap.

[10Toes]

They actually feel normal. Great pressure. The only thing is, it may shut off at anytime I push the clutch and brake, who knows when. Then the idling issue of course.

I forgot to mention that the car does push the brake pedal up if I have it pressed down when I turn it off with the key when parked. This means the pressure escapes to the booster when I turn it off, forcing the pedal up.

All I am afraid of is having the turn off while turning, then having the steering wheel lock as a result and uncontrollably slammig into something. The pressure is nil when the car is off. Very dangerous!

The steering wheel shouldn't lock as long as the key is still in the on position.

[graphikg]

replace the valve, they're pretty cheap.

You are talking about the girling valve between the booster and the hose to the manifold right?