Originally Posted by Jay462

Thanks to member Chomper for the NPP mufflers - good guy!

Added the mufflers to my '09 Z51. Was running them open full time. The car is completely stock.

I finally got around to having the time to install an exhaust controller. I didn't want to rely on engine vacuum, because:

1. If something went wrong with the vacuum lines, fittings, or controller components - I might get a vacuum leak, and that would suck to have to chase around.
2. I didn't want to try to break off that little tab on the back of the intake.
3. I didn't want to tap into the brake booster.

Solution? Well, the engine is just a big vacuum pump. So I found a small vacuum pump. A Dorman pump intended for Ford Diesel trucks.


The vacuum tubing goes from each muffler to a tee, to a line, and that lines comes up through the bottom of the bumper assembly to the inside of the bumper into the wall cavity through a little hole that is above some pre-existing green wire that has a grommet. Above that green wire and grommet, if you peel back some little rubbery tape, there is an existing hole. There is another one on the other side too. I made that hole slighty bigger with a drill, and fed the vacuum tube through it. Then the tubing connects to the solenoid, then from the solenoid to the pump.

The solenoid is in-between the pump and the mufflers, because although the pump shuts off automatically when its full vacuum is achieved, if you cut the power the the pump, it will not release vacuum. It must have an internal check valve. I didn't want to modify the pump because it doesn't look very easy to get into.... so using the solenoid to vent the line to atmosphere works well.

To me, this setup is much better than the current "NPP in a box" because:

1. No engine vacuum line
2. No remote control
3. Switch is reachable by your hand instead of in the "dead pedal" location
4. Components are easily replaceable if they fail
5. DIY is neat

Back in "the day" I guess (like maybe almost 10 years ago) it seems the "NPP in a Box" guy's product actually used a vacuum pump. I read on the forum on some old post before I started this project that he stopped using the vacuum pump because he couldn't source them anymore. Apparently the one he was using was really tiny and used in military applications or something. Edit: actually, he may have been using a medical device for asthma patients. Regardless.... All I know is the pump that I used is very common, and available everywhere. It's like $50.

When I turn the system on, the pump turns on and makes noise for a few seconds. The exhaust valves then fully close, and the pump turns off automatically because it has reached ~12 to 15 inHg. When I turn the system off, air dumps through the solenoid and exhaust is back to "loud" and nothing is receiving power.

The cruise-control fuse is ignition switchable (like the seat heater fuse). Therefore, the system draws no power unless the car is on.

I hope this helps someone. I did A LOT of searching to plan this project. Camaro forums and Corvette forums helped. The AC/Delco solenoid operation was gleaned from the Camaro guys and some Volvo guys- I'll have to tell them it's unreliable if they haven't already figured that out....

This is awesome! Now I can have it quiet on long road trips (the drone with NPP in the full open position is annoying as hell to me).

Happy 4th!

Originally Posted by rybern

I just found this thread and this seems to be a great way to add NPP. I like the simple open or close at the flip of a switch. I will do a dead peddle switch if I end up doing this.

Originally Posted by Dcasole

You can do the same thing with "NPP in a BOX" , comes with everything you need to control NPP mufflers including remotes that you can slave to your homelink buttons if u like

Dave

Originally Posted by C6_Prodigy

How are your Doorman vacuum pumps holding up?

I am reading mixed reviews of how long they last online and am contemplating spending $120 on the Motorcraft/OEM Ford pump which comes with a 2 year warranty.

I'm trying to buy and assemble this DIY in the next month or so. Looks very simple since I don't need to run any additional wires. I already have NPP in a box but I keep having issues with the vacuum solenoid not holding vacuum, as well as losing vacuum during heavy throttle that you get when relying on engine vacuum. This solution should solve my issues and be more reliable.

Originally Posted by long_tall_texan

PM me if you'd like a deal on a lot of this kit.

Originally Posted by Vetterator

Since i put mine together almost 6 years ago its been trouble free. No issues at all.

Originally Posted by C6_Prodigy

How are your Dorman vacuum pumps holding up?

I am reading mixed reviews of how long they last online and am contemplating spending $120 on the Motorcraft/OEM Ford pump which comes with a 2 year warranty.

I'm trying to buy and assemble this DIY in the next month or so. Looks very simple since I don't need to run any additional wires. I already have NPP in a box but I keep having issues with the vacuum solenoid not holding vacuum, as well as losing vacuum during heavy throttle that you get when relying on engine vacuum. This solution should solve my issues and be more reliable.

Edit: I went ahead and ordered the vacuum pump from Autozone. It was $111 after a 20% discount. They offer a lifetime warranty so I don't feel bad paying extra for the ability to take it down the street to swap it out.

Originally Posted by Tim90NOS

2 years and zero issues from the pump and any other components. I relocated everything to the driver side trunk cubby, will post a pic as it worked out. Considered putting it all in pass cubby where the onstar used to be… which would be a nice repurposing of space.

Originally Posted by MDC9966

I’d like to see that, thanks

Originally Posted by Jay462

Here's the pump and the valve wired together, getting power from the add-a-fuse and ground connection from the passenger fuse panel, and with the vacuum lines connected to the proper ports.



I hope this helps someone. I did A LOT of searching to plan this project.

Originally Posted by C6_Prodigy

​​​​​​
@Jay462 - I just want to say thank you for your research and this thread. You made it so easy for me. This photo along with the rest of the info you shared allowed me to hook this system up and it worked the very first try.

I already had NPP in a box so I re-used the remote feature to get power to the vacuum pump and Mac valve.

I still have a small vacuum leak that I assume must be at the "T" between the two mufflers. I zip tied every other vacuum connection and the pump will kick on for about 1/4 second every 10-15 seconds. I'll get to that later, but this serves the purpose of allowing me to get out of my neighborhood and going to the inspection station with headers (eventually) without being obnoxious.

Cleaned up the best I could. The pump I screwed into the trunk. With the weight of it + the Mac valve attached, I didn't trust Velcro alone.

Power taken from my old NPP in a box setup and connected to the switch that plugs into the vacuum pump.

Originally Posted by Tim90NOS

Nice install. I chased a similar leak and it turned out to be one of my actuators on the muffler itself, you may want to start there... a golf tee works nicely to plug the line

Originally Posted by C6_Prodigy

How did you fix the leak if it was the actuator? I'm going back out to the garage to try to find it. Now that I've taken a break I want to see if I can't finish this thing off and call it done. I've had intermittent issues with the NPP working for the better part of 2 years so I would love to close this chapter and focus on other things.

​​​​​​Edit: Every single connection feels secure and is now zip tied for extra measure. I used Teflon tape on the Mac valve fittings when I installed them so I'm assuming they are good. Who knows. Maybe when I'm driving I won't hear the pump kicking on and off but it seems a little excessive to be 100% content with it.

You can hear the pump kick on for a split second around 11 seconds into this clip.

Originally Posted by Tim90NOS

FWIW none of my connections are zip tied, I traced the leak to drivers side solenoid/actuator. I couldn't find new replacement actuators, tried to buy a pair from a forum member and lost interest. Between cam/headers/dynamat interior the intermittent pump noise doesnt bother me and I moved on to other projects. Before I buy new actuators I may try sealing the one I have by recrimping the edges or JB weld etc.

I love this system, nice stealthy startups in my quiet neighborhood.. no screaming babies or angry neighbors. Easy cruising with no drone on longer trips... and an angry terror when the valves are open.

Originally Posted by C6_Prodigy

@Tim90NOS - Found it!

https://www.corvetteforum.com/forums...ividually.html