Interesting brake/Vacuum issue

[freakyjason]

This has been going on for quite some time but I have never looked into it because the car runs great with excellent vacuum and it stops great. First off, it's an sr20det with JWT s3 cams (which will affect vacuum to some extent) and it also has Z32 brakes with the stock brake booster and master cyl. Now my issue is that when the car is running and at idle, if i pump my brakes rapidly, the idle starts to be poor, the car sounds almost as though it's going to die (which it never does no matter how much you pump the brakes), and the vacuum becomes visibly worse (according to my gauge). Now, I have no idea why this would be happening but my only thought is that perhaps the brake booster check valve has gone bad. The brake booster passes the pressure check outlined in the FSM though. Any thoughts?

[compactfean]

the check valve would have been the first thing I checked. The amount of time it took you to post this you could have checked it. Lol Seriously easy.

[freakyjason]

Well, considering my car is under a foot of snow, is about 2 city blocks away, has no engine in it or brakes on it at the moment, I think technically that would have taken longer to check haha. But it's been doing this for over a year, so I get your point. But how do you even check the check valve?

[compactfean]

Just blow through it. You should be able to blow through it one way and not the other way. If it leaks on the sealed side its bad.

[freakyjason]

Haha seems simple enough. Thanks for the tip!

[OutToWinPAHC]

Could also be a bad diaphragm on the booster. Cheap for leaks, clamp it all.