car dieing when brakes pressed

[anti tyler]

so heres a little background info,

93' 240sx ka24de-t
rebuilt internals
t3/t4 turbo
megan coilovers
blah blah blah.


I seem to be stuck on an issue that randomly popped up when i came home yesterday.


car runs fine (except bad transmission, being replaced wednesday)
idles alright, accelerates like a beast, and is fast as hell.

but for some reason when i go to press the brakes the rpms drop below idle and seems to die. starts back up perfectly fine, and runs fine after, but i end up having to use the e-brake to stop the car which makes it very difficult to drive.

already had some suggestions thrown out there, disconnect the vacuum hose to the booster and see if it keeps doing it, if not then the booster is bad, but when i disconnect the booster vacuum hose it does the same thing so im assuming my booster is good.

went to the auto parts store and tried replacing the hose all together thinking it might be a leak? nope, still does it.

some one, something, somewhere. help!!!

[niteridaz503]

sounds like a vacuum leak honestly have you checked ALL you vacuum lines?

[Sam_Well.13]

hmm... puzzlin'.. usually this happens when you have a vacuum leak, but you said you covered that already.

did you check if ALL your vacuum hoses are connected?

[anti tyler]

well call me a retard, but i only checked and replaced the hose going from the booster to the intake side of the block. havent really checked EVERY vacuum line, its been a while (been away on deployment) so id have to look up a manual or something seeing as i dont know what lines are vacuum lines.


question, would any of you recommend getting a vacuum line checker from like autozone or something?

[niteridaz503]

^^^^

No prob man just go & check everything as far as vacuum lines also make sure everything's clamped too

[anti tyler]

im gonna head to the store and grab that vacuum line checker. so i can get this figured out before i run out of daylight. ill def post back tonight with the results. thanks for the help so far

[niteridaz503]

Keep us updated if you can also make sure your alternator is in working order because i had an issue kinda related to what you're having & it was due to a bad alternator too just an FYI

[anti tyler]

alright im not gonna lie, i just got this vacuum checker and i have not the slightest clue how to check for vacuum leaks.

[1ZlowZ]

haha funny, but check the vacuum line going to the brake booster.

[anti tyler]

so i forgot to mention when the brake is pressed it makes a sort of hissing noise, thus pretty much giving it away that theres a leak IN the booster.

agree/disagree ?

[heavenboundkevin]

Keep us updated if you can also make sure your alternator is in working order because i had an issue kinda related to what you're having & it was due to a bad alternator too just an FYI

SAME THING. well you say there is a hiss, but if nothing you do helps, try to swap alternators and see if that helps. good luck.

[Sam_Well.13]

no need to swap alternator...start your car, unplug your battery then press on the brake. if it dies, then it could be your alternator.

but autozone has a gadget that could check your alternator and battery while still in the car.

[OLDSCHOOLRICE]

Sounds like a booster. The diaphragm inside the booster is leaking causing a large vacuum leak when the brake pedal is depressed.

There's no logical reason that a bad alternator would cause the car to die only when stepping on the brakes.

[anti tyler]

^^ that makes absolute sense now, i have some money, if anything replacing the booster wouldnt be a bad idea.

but yeah, makes sense, it only dies when pressing the break, and when pressing the break you can hear a hiss coming from inside the booster. ill order one tomorrow and post bad with an update when i install it!

thanks guys

[BILLFISHER21]

100% booster

[heavenboundkevin]

Sounds like a booster. The diaphragm inside the booster is leaking causing a large vacuum leak when the brake pedal is depressed.

There's no logical reason that a bad alternator would cause the car to die only when stepping on the brakes.

yeah well myself and theat other guy had this same problem. My logic tells me that maybe when you press on your brake, it lights up the brake lights, which draw electricity, and kills the car.

when i was having this problem, my automatic seatbelts were acting funny (moving accross the track slowly) so it was indeed some sort of electrical problem that was fixed by swapping alternators.

But, it doesnt sound like this is the OP's problem. OP please report back once you figure it out and post what you did to fix it.

[nathanong87]

i have similar symptoms too. it's frustrating.

[Datenshi]

but for some reason when i go to press the brakes the rpms drop below idle and seems to die. starts back up perfectly fine, and runs fine after, but i end up having to use the e-brake to stop the car which makes it very difficult to drive.


Are you seriously driving around without brakes.. and just your e-brake? You, sir, are a fuckin MANIAC.

roflmao.

[anti tyler]

Are you seriously driving around without brakes.. and just your e-brake? You, sir, are a fuckin MANIAC.

roflmao.


negative, i have an SUV i drive, i take the 240 around the block to test my progress. which sucks because i installed my new transmission yesterday and filled it with 80w-90 gear oil and on the way home it started to sound like metal grinding (obv) i figured the oil just needed to get in the gears and what not, but i pulled into my neighborhood and it got REALLY loud. so im gettin really frustrated with this car at the moment.

booster update in a day or two when it comes in

[niteridaz503]

What was the condition of the tranny & what brand oil was it. I use 75w-90 Royal Purple in mine but update us on the booster issue too sounds like that's where the issues been.

[anti tyler]

it was a used one, about the only one i could find in a 100mile radius of my place. i mean it shifts 130% better then my old one, didnt have any imperfections that i saw, the shop we got it from tested it and put a 90 day warranty on it, but im sure if it was grinding when they tested it they wouldnt of gave it to me. im thinkin theres only a few real possibilities. its not the throw out bearing, its got to be something with the gears. or possibly the driveshaft inside the tranny.

and in all honesty the loudness when i got into my neighborhood sounded a lot like the tranny wasnt bolted 100% like its shaking. which is always a possibility.


^^^^^^
update again, i just took it for a ride around my block, the noise matched the rpm, whether in gear or not. was still there, i got to the end of my street made a u-turn and the noise went away.
im still hoping it was the fact that the tranny was drained of all fluids and just needed to lubricate itself again.

btw it was valvoline gear oil i used

[OLDSCHOOLRICE]

yeah well myself and theat other guy had this same problem. My logic tells me that maybe when you press on your brake, it lights up the brake lights, which draw electricity, and kills the car.

when i was having this problem, my automatic seatbelts were acting funny (moving accross the track slowly) so it was indeed some sort of electrical problem that was fixed by swapping alternators.

But, it doesnt sound like this is the OP's problem. OP please report back once you figure it out and post what you did to fix it.

You're right, the brake lights do draw some amperage. However for the brake lights to be the only draw to cause the issue isn't logical. The headlights, radio, blower motor, rear defroster, and possibly power windows also draw amperage (some much more than the brake lights), but the OP doesn't mention these components as a cause of the issue.

[supreme_1]

try and unplug the huge line going to the booster and plug it, with your car idling press on your brakes and see if it dies.

[anti tyler]

You're right, the brake lights do draw some amperage. However for the brake lights to be the only draw to cause the issue isn't logical. The headlights, radio, blower motor, rear defroster, and possibly power windows also draw amperage (some much more than the brake lights), but the OP doesn't mention these components as a cause of the issue.


exactly my point, no power windows, no defroster, and no a/c lol, it's not a power issue,


@supreme_1

I've already done that and it brakes fine, with the exception of having the booster to make braking easier. thus proving it's either a bad diaphragm in the booster, or the whole booster is bad.

[Sergio180sx]

i kinda have that problem too!1 i just got my alternator rebuilt on my rb25 and a new battery and new wiring on my charging system and when i push the brake down it slows my fans down and idle drops to its so frusteraing...and when i try to start and it goes tick tick tick tick and then starts ugh!1 i think its my starter too but idk

[udon!]

This happened on my old coupe and it even stalled one time. Never figured you why it did it.

[240Shwag]

You're right, the brake lights do draw some amperage. However for the brake lights to be the only draw to cause the issue isn't logical. The headlights, radio, blower motor, rear defroster, and possibly power windows also draw amperage (some much more than the brake lights), but the OP doesn't mention these components as a cause of the issue.

Unless of course they are shorting to ground and for some reason or another its not popping a fuse. Doubtful situation.

Find a used booster in the classified section of this forum.

[codyace]

Is your blow off valve recirculated?

[anti tyler]

Is your blow off valve recirculated?


not sure to be honest, but i think it is.

i have a new booster, just SERIOUSLY slacking on putting it in. the back of the brake petal is really hard to get to.

[anti tyler]

this is old and all, just thought i'd update it;

replaced booster, breaks are good.

[modulation]

this is old and all, just thought i'd update it;

replaced booster, breaks are good.

Thanks for updating you problem. We all hate when we search the internets to find a problem exactly like ours with no solution ever posted.

[chiboy002]

i kinda have the same problem except i have a 91 hatch stock ka-de

when i press on the brakes my idle drops to like 400rpm. Same when i decelerate, wtf could it be? I think i might need a new alternator, is there any place i can buy a good one?

[g-via]

did you read this thread at all?

[chiboy002]

did you read this thread at all?
did you? my car doesnt die. different scenario and my alternator is fine. I'd assume if it was a vacuum leak then my car would die

[g-via]

you car doesn't need to DIE for it to be a vacuum leak, try again.

[modulation]

you car doesn't need to DIE for it to be a vacuum leak, try again.

Or start a new thread since you think your problem is so different then this one.

[klits562]

i can almost guarantee that most situations involved with your car bogging or dieing or any rpm change when hitting the brakes is because of vacuum leak!
Every topic i have seen about this has lead to vacuum leak. I had the same issue with my car and it was vacuum leak.
the OP had the same issue and it was vacuum leak!
its vacuum leak!