Booster slows engine when brakes applied

[Clunker]

I just finished installing a new power brake booster, and I'm not sure that it is working properly. When you press the brakes, the engine speed drops a bit . Then, when you release the brakes, it does it again. Did I get a defective remanufactured booster, or did I screw up somewhere in the installation?

[Mach428]

Sounds normal, depending on how much of a decline in RPMs

[Clunker]

RPM's only drop about 50 or less for a split second, and neutral idle speed is a tad low at 600. I think I still have a vacuum leak somewhere too, so it might be related to that as well.

[colnago]

I'd say to chase down your vacuum leaks first, then that should tell you if you have a defective booster. I just converted to front disc brakes, and noticed a hesitation when accelerating at a stop. Long story short, I finally realized the tranny fluid was low, so it didn’t have any connection to my new brakes.

When working on any vacuum leaks, be sure to check around the booster, too, just in case it's also providing a new vacuum leak.

Joseph