Two Toes

Just got our NRB 2015 three days ago-----wow
Two questions:

(1) What fuse do you pull to disable the multi-mode exhaust? There is no ID related to that fuse in the engine compartment fuse box.

(2) I think the battery is in the back. How is it accessed?

OnPoint

Fuse #41 for 2014 Stingrays and #42 for 2015s.

rponfick

I have noticed the reference to fuse no. 41 to disable the exhaust before, but in looking on page 10-39 of my 2014 Owner's manual, it lists fuse no. 32 for exhaust valve 1, and fuse no. 41 for exhaust valve 2. Is there a fuse for each exhaust valve, since there are two of them?

I'm confused. But, I am easily confused.

Ralph

OnPoint

Fuse 32 is for the AFM valves (the exhaust valves activated when your car is in AFM/Eco mode). You don't want to pull that - it will throw a code/check engine light. 41 (for 2014) or 42 (for 2015) control the NPP valves at the back of the exhaust - and pulling that one doesn't throw a code.

Two Toes

Thank you, #42 it is.

rponfick

I'm still confused. Isn't AFM when the exhaust cycles between open and closed when cruising to prevent the "drone" in 4 cyl. mode? So, by leaving 32 in it will still cause the exhaust to cycle between open and closed? Or, will pulling fuse 41 keep the exhaust open all the time?

Ralph

OnPoint

There are two sets of exhaust valves. One set, behind the cats, but before the rear of the car are the valves that activate when the car is in AFM/eco (V4) mode and they help prevent poor exhaust note in V4 mode.

The other set are the valves at the rear of the exhaust system - the NPP valves on the muffler tips that control sound of the exhaust relative to the mufflers. If you pull fuse 41 (2014) or 42(2105) it will keep those valves open all the time. The AFM valves upstream will continue to operate when the engine goes in V4 mode, but the NPP valves aft of the mufflers will not operate and will be defaulted to open (i.e. louder).

CaryBob

Have you tried setting engine sound management to "off"? If you've only had the car a few days it's possible that will produce the sound you're looking for.

themonk

for the automatics.

rponfick

OnPoint, thanks for the information. You obviously know your stuff.

One final question (I promise), I have my sound management setting in the "off" position. Is is correct to say that the NPP valves still cycle with the AFM even in the "off" position, and pulling the fuse will keep them open at all times? I guess the question is what does pulling the fuse do.


On a recent trip to Calif., I had my management set on off and the constant tone change in the mountains, etc., while cycling through AFM was annoying. I set my management back to "on" and it was less noticeable. In town, I prefer the louder sound with the management set to off.

Thanks for your expertise. Ralph

OnPoint

Yes, even with the sound management set to off the car under certain circumstances will continue to operate the NPP valves. Most report the occurrence in situations similar to what you described - highway speed when on/off loading the engine. I suspect GM did that because even if folks choose "off" for the sound management, GM may have concluded that they still needed to control for potential scenarios of exhaust drone for those customers not used to hearing a throatier exhaust.

So pulling the fuse is the only way to run the exhaust open all the time.

realefire

if you go to your settings menu you can keep your exhaust on the sport mode 24/7....no need to pull a fuse sorry if I misunderstood your question

themonk

nope, sound management off, still activates it.....pull the fuse, end of story.

Vette Nut

I am running without Fuse #42

xp800

All the details here if you really want them... The NPP fuse threads are quite frequent.

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

newskatercat

I can't find an off position, in engine sound management, in my 2015! Was it changed in the 2015?

xp800

Page 5-46 of the manual...

newskatercat

Thanks for the quick reply, without the, READ THE MANUAL!! I didn't realize auto = off! I actually went to the dealer, before I posted this! Salesman said, it was changed in 2015, because keeping it in off, made the valves stick! I am reading the manual, a little at a time! Not as much fun as driving my few day old car! Best!

xp800

No worries. I've been a victim of the "RTFM" as well.

Actually, Auto setting follows the Driving Mode dial. This is the default. "Off" leaves the NPP valves open all (but actually only most) of the time.

Your salesman is incorrect. There is nothing different for 2015. The valves being open are when there's no power going to the NPP valves. They are held closed by power.

The effect of this mode is very noticeable in manual trans cars since V4 mode only happens in eco. In automatics, V4 happens all the time and the exhaust will be quiet even if this setting is OFF.

As above, read here for all the gory details:

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

culpeperbob

I didn't know about the fuse, but in the manual you can turn the sound off and the baffles will stay open in all modes. It is somewhere on the radio screen and talks about the sound in the manual.