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Old 07-05-2020, 06:02 PM   #1
Whitey0817
 
Drives: 2013 2SS
Join Date: Jun 2020
Location: Cincinnati, OH
Posts: 4
Attention NPP gurus! I think I've got a vacuum leak...

For starters, its a 2013 SS NPP from the factory, running a manual switch to control the solenoid, and Hooker axle back NPP mufflers(discontinued?). The car came with straight pipes from the previous owner. How long should that little reservoir hold enough vacuum to close the flaps on startup? Since I installed the mufflers and switch, it's always fired up with them open, with my 3-way switch in the closed position, its never been a problem since it would only take 1-2 seconds to pull enough vacuum to close the flaps.(Could start up with garage door closed) I recently did a cam swap, and as expected, lost some vacuum especially at idle. Now they wont close until I get the engine under load and get up my street a little ways. Not a huge deal, but I work at 5am and don't want to piss off the neighbors if I want to drive it to work on a nice day. The valves hold closed while driving just fine, but if i'm sitting in a drive-thru or something for a few minutes I can hear the exhaust getting gradually louder. This doesn't sound normal...I'm guessing a leak somewhere behind the check valve as there are no symptoms of any vacuum leaks with the engine or braking etc...

If it's not a leak, should I look into a larger reservoir? What about a separate electric vacuum pump to isolate the NPP system from engine vacuum? Should be easy to do, and would allow me to pull vacuum before starting the engine. Any advice would be appreciated.

Thanks, Dan
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