Hi all -

Not really troubleshooting but I need some information. I just bought a 2008 Coupe and it has the NPP exhaust. At first I thought it just had great pipes and Corvette team had done something right when it growled on start.

Went out and bought a mild to wild controller and I got no change - so silly me I rechecked the baffles and they are open all the time. For normal driving that means the annoying drone that everyone talks about.

I have checked the fuse (obviously) when I put in the mild to wild. So if I understand it the only thing easily messed with is the vacuum line. I do not have a service manual yet but i did find a stainless steel line on the left rear of the intake.

Question #1 - Is that the vacuum line to the NPP or is it forward on the bellows near the MAF?

Question #2 - If that is the line then it appears intact and I presume the the NPP fails to 'open baffles' - since that is what the m2w seems to be a very fancy 'fuse puller.' LOL

That leaves me with either the wiring to the solenoid or the vacuum line removed and plugged at the rear. I haven't lifted the car so my real question is if the wiring or vacuum line need to be reattached at the rear where are they and can I access them without lifting the car?


Thanks in advance!

 

The NPP vacuum source is at the back of the intake manifold, driver's side. See pics here:

http://forums.corvetteforum.com/1579694402-post3.html


You can access the vacuum lines on the 2 muffler canisters without lifting the car but it would be easier lifted. Here's a quick diagostic for the vacuum:

http://forums.corvetteforum.com/1578891449-post6.html

 

Super - Thanks much! Bottom line they do fail open - sort of like those wonderful vacuum headlight jobbies i had on my '72. Sure wish I still had that one. i will have to look see if there is a problem with the vacuum. The hose I saw is not way back there more like 1/3 of the way from the back of the engine on the driver's side. I may get cured of my ignorance when I receive the SM I have on order. 1 picture yada yada,

and I thank the guy for the post on the vacuum i had to read it a couple of times to get the jist but it is late at night lol

Again thanks much - sure hope it isn't an actuator as I am sure they are not cheap - well maybe cheap but not inexpensive lol

 

Last night, my exhaust stuck open and I have a weekend tripwith the wife coming up, she does NOT like the rumble of the open exhaust. When I got home and shut the engine off, the NPP was in closed, less noisy mode upon the restart. Does anybody have any experieince with a problem that comes and goes? And if you did, can you give me a solution?

NCCARDFAN