engine sputters when I hit the breaks and eventually stalls

[dvbagnasco]

Hey guys. I would really appreciate the help if you can give it.

A little bit about my car first.


My car is a 1990 Nissan 240sx with an SR20DET "Black Top" engine, cold air intake, T25 turbo, and a bunch of other stuff done to it.


My problem is.......everytime i am driving around town, I will push the clutch in and hit the brakes to come to a stop at a red light. Well, when I do this my tachometer drops from a normal 750 rpm to 1000 rpm to 500 rpm and sometimes down to 0 rpm where it stalls....obviously.


I got home, opened my hood up and checked the brake fluid......It is a rustic brown color but it is still full. I havent flushed the brake system yet until I get an answer that maybe it needs new brake fluid.


After checking the brake fluid and seeing that it is still full, I turned the car back on, let it idle at 900 rpm (normal) and then hit the brake. I noticed everytime I hit the brake the rpm gauge would go down to about 700-800 rpm. This makes me think maybe its the alternator when the brake lights come on or maybe I need a new brake cylinder......but then I got to thinking that when I brake with the car still in gear (not in neutral) the tachometer does not go down to 500-0 rpm. This only happens when I disengage my clutch or shift the car into neutral.


Any help would be appreciated.

[slideways...]

vacuum leak inside your brake booster

brake booster is run off vacuum so when you step on the brake it leaks vacuum through the booster. most likely caused by a bad brake master cylinder so replace the MC and booster at the same time. good time to flush fluid also.

[dvbagnasco]

I took my car to Tires Plus today and they told me it was a bad brake booster. They had to special order the part and i'll get it fixed on monday. Thanks slideways. I got plenty of responses on other forums ranging from dirty idle air control valve, bad brake master cylinder, etc. etc.

[ca18769]

any chance that could be the same thing with my car? completely diff car, but same problem!. mines auto, and a 96 240.its drops revs from like 7-8 to just barely 5 and sputters to stall. starts back up just fine...

[dvbagnasco]

I have since gotten this problem fixed. I replaced the brake booster and it kept stalling. So then I replaced the brake master cylinder and that fixed the problem.

So the brake master cylinder first. If its not that then its the brake booster.