ZackWirth

Ok so I have a '14 Z51 with a texas speed sv cam, afe intake and texas speed headers and x pipe. All cats have been deleted..

Stock mufflers are on the car.

In sport mode it sounds pretty good but when i start driving down the road and at about 30 mph one of the valve things shut and it seriously sounds like complete ****!!!!!

Extremely annoying and im sick of it.. What can i do to fix this annoyance?

Thinking of trying out the flowmaster set up but I really want the katech tip.

Also notice on some of the corsa and flowmaster kits it shows those valve things behind the mufflers. Are those going to be active?

Has anyone done a complete custom flowmaster set up? Thanks

eboggs_jkvl

I think you're going to be told to remove a fuse. I'll wait for the barrage.


Elmer

ZackWirth

fuse 41-42? thats it?

eboggs_jkvl

I believe it keeps the flaps open on the NPP.


Elmer

meyerweb

Do you have an automatic? If so, does it act the same way if you have the transmission in manual mode? If not, search on "AFM," and on Range AFM Disabler. There's a completely different set of valves related to the engine going into V4 mode, which it does frequently on automatic equipped cars. Nothing you do to the NPP valves will prevent that.

Theta

Both members above are correct. If you really feel like reading into it, here's a (large) repository of information on the subject:

https://www.corvetteforum.com/forums...ck-result.html



.

tblu92

Yes all are correct--There are actually 2 sets of butterflies ( 4 in total) on your exhaust
The further back ones are for the NPP exhaust that opens up all 4 tips on your mufflers
Read about pulling this fuse to keep them open all the time
The 2d set of butterflies are further forward of the mufflers---These CLOSE when your engine goes into 4 cylinder mode " AFM"
The easiest fix is to have your tuner or get the Diablo and turn the AFM OFF permanently---Valve will stay open all the time---and the AFM ?? who needs it !!!!!!

bob guzzy

I pulled #42 fuse on my car, best move for a decent sounding exhaust, just like a C6 with NPP wide open like I ran my both C 6's.

xp800

Pull fuse #41 for a 2014. Assuming with the AFM has been deleted by the tuner when cam was installed. So whether M7/A6 you're not going into V4/AFM mode. That fixes 95% of the problem if A6.

Not one suggestion to "go to the settings" to have NPP open all the time...and subsequent banter?!? This HAS to be a first!!

To my CF brethren preaching the NPP gospel here..-sniff-...you guys are awesome. The NPP is strong with you.

bob guzzy

If you use the infotainment screen to tell your exhaust to stay open they will open, but will close on their own at set MPH.

just when you want the rumble they close and sound like a normal quiet car I wanted my c7 to sound like my c6 did with NPP pulling fuse 42 on a 2015 car is how you get that sound.

It's easy enough to put a switch on this fuse 42 or 43 and open and close them at will, or you can wait for the gentlemen who is making the controller, then you can have the mild to wild set up like they had on c6's.

hawkgfr

Like a couple have said...the fuse is not the issue...it is the other valves that closes or open when afm kicks in..


I hate it too....Pulling the fuse is the same as track mode. (on a 15)

Higgs Boson

if you already have a cam then I am sure you have a tune.....just disable AFM in the tune and you are good to go. of course, you went with that cam I assume to retain AFM and if you do want to retain it, the funky exhaust will remain.

Theta

Fuse 42 would be the correct fuse for a 2015 (41 for a 2014).

The standalone controller is not necessary for those that already have NPP. A simple switch mod is all that is needed:

https://www.corvetteforum.com/forums...e-control.html



There have been some that act funky in that regard according to some owners who have posted in the lengthy Fuse Pull thread. Probably a software issue.

OP: I'll agree with the others here - In the end, it's usually AFM that's the issue.

SharkGrayStingray

my AFM became a lot louder and annoying after my corsa xtreme and double helix install. I got a diablosport intune and deleted AFM and all sounds good