NPP Exhaust Vacuum Routing

[SubSonic]

I recently had the NPP exhaust replaced by a dealer on my 14 SS (Long Story). However, after making my way most of the way back home (as soon as I rolled down the windows), I realized that the flaps in the system were staying open all the time.

I don't mind the volume, but obviously, after having a brand new system installed, I expect it to work. This is an NPP equipped car, so all of the vacuum pieces should already be in place. But from what I can see, only one of the two nipples on the right muffler have a vacuum hose attached.

If it comes down to it, I'll bring it back to the dealership, but if it's not overly complicated, I'll run vacuum lines myself and save the hour/1.5 hour drive.

I just wanted to see if any of you guys had pictures or diagrams of the system that would help with diagnostics.

Thanks!

[Dropspeed]

It should be self explanatory when you get under there and look as the hoses all dead end at the actuators. I will try to get a picture late tonight.

When they drop of remove the exhaust the hoses stay attached to the rear subframe....I assume you will just need to plug them back onto the actuators

[SubSonic]

Originally Posted by Dropspeed

It should be self explanatory when you get under there and look as the hoses all dead end at the actuators. I will try to get a picture late tonight.

When they drop of remove the exhaust the hoses stay attached to the rear subframe....I assume you will just need to plug them back onto the actuators

I'll throw my head under there at lunch and see if there's a dangling vac line I missed. I'll update then.

If no dice, if you could snap a picture later I'd definitely appreciate it.

[Dropspeed]

Originally Posted by SubSonic

I'll throw my head under there at lunch and see if there's a dangling vac line I missed. I'll update then.

If no dice, if you could snap a picture later I'd definitely appreciate it.

It wont really be dangling...They are hard plastic lines with quick disconnects on the ends....I doubt you will have any issues if they are just sitting there.

[SubSonic]

Shoulda guessed it wouldn't be that easy. And yes, you were right about the lines. Found the vacuum line to the right (looking from rear) muffler solonoid. Plugged it in. Now the flaps stay shut on both sides at all RPMs and at idle.

This my warrant a trip back because I can only imagine a tech having the same issue and just leaving one line unplugged.

I know if a fuse is removed or if there's a vacuum leak (like the major one it appears I had) they fail open. But I'm not sure about a failed shut cause.

Edit:

Did some more diagnostic. With vacuum hooked up the flaps stay shut at all times. Even when the car is off. The vacuum line still holds vacuum when the car is off, which explains why they stay shut. It's almost as if there's a one way valve in the system allowing vacuum to pull but not release. So once any vacuum has been pulled, they stay shut until a line is disconnected.

[christianchevell]

Forza had some fairly detailed instructions when I installed there three way switch you may be able to see them there.