IS this a bad booster...or engine vacuum problem?

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
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Massachusetts
I know i need to replace 1 of 2 parts...but which one I am not sure of. I want to get some opinions.

Symptoms. I've always suspected clogged cats. I have a stock H-pipe on my car because i hated my off-road pipe. Unfortunately i ran it without the smog pump for some time. The engine seems slow to rev and feels like i am losing power somewhere. I did a vac test and everything seemed fine. 25 inHg at idle, drops to 20 with a blip and then rises up. Same if i hold 2000 RPM. Car has a stock cam BTW.

As for the booster. It feels inconsistent. It def feels like it has more assist at lower RPM. I stepped on the brakes hard yesterday at 4000RPM and it felt like i was using all leg muscle. But ifi push the clutch in and let the RPM's drop and hit the brakes, i have assist. I've tested the booster by hooking a vac pump and gauge directly to it. It holds vac, doesn't leak down over time and feels like it does at idle.

SO.....new booster time (it's a used 1995 SN95 booster) or replace the h-pipe? I prob want to do the h-pipe anyway. Been looking for a catted mod-pipe on CL or for sale locally. If i cant find one i'm sure i can grab a stock h-pipe to use. Or does this sound more like a booster issue?

I have an autometer boost/vac gauge that i didn't really want to install because i don't have a blower yet, but that vac portion of the gauge could prob come in handy now to see my vac reading at 4000 RPM when i've lost my assist :shrug:
 
I would look into the booster. I also have a 95 SN95 booster and was having the same problems. I have an off-road H on my car, so I dont know if your cats are causing the problem. I replaced the booster with a $10 JY piece (seen it was new....) and i have awesome pedal at any RPM....
 
Yeah part of me says booster as well...esp since my vac readings seem normal.

I'm gonna do a new H-pipe anyway (catted) but if its the booster i want to take care of that first. IMHO it's easier than swapping h-pipes