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Old 07-13-2014, 06:36 PM   #1
freebird
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Default NPP Exhaust Question...

Since there is no Mild2Wild for the C7, how can you keep the flaps open. Love the sound when they are open full time..
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Old 07-13-2014, 06:40 PM   #2
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It is controlled in the touchscreen menu settings. Set it to the driving mode you are in or open most of the time.
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Old 07-13-2014, 06:41 PM   #3
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Set to off on setting screen and pull fuse 41(yellow one).
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Old 07-13-2014, 06:42 PM   #4
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Quote:
Originally Posted by vettnutt View Post
It is controlled in the touchscreen menu settings. Set it to the driving mode you are in or open most of the time.
I wish this button were on the main screen. It's dangerous to go so deeply into the touch screen menu's to switch it while you're driving.

Why not just have one button on the main screen "NPP On/ Off" to hit? Seems so obvious.
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Old 07-13-2014, 06:43 PM   #5
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Correct me if I'm wrong when ever the car drops into the V4 aka AFM mode the exhaust valves close.

So you'd need to install a "tune" to disable AFM from happening? Right????
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Old 07-13-2014, 06:47 PM   #6
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On the M7, leave out of eco and AFM never works. Auto I think your screwed.
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Old 07-13-2014, 07:26 PM   #7
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Quote:
Originally Posted by Sin City View Post
I wish this button were on the main screen. It's dangerous to go so deeply into the touch screen menu's to switch it while you're driving.

Why not just have one button on the main screen "NPP On/ Off" to hit? Seems so obvious.
Not enough room on screen for all our wants.
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Old 07-13-2014, 07:28 PM   #8
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Originally Posted by Bigdog9586 View Post
Not enough room on screen for all our wants.
This is what bugs me about software people (and I work with a lot of them).

They like to think they know everything so "choice" is not an option.

"Why should anyone want to change it? It's perfect the way I designed it!"
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Old 07-13-2014, 07:42 PM   #9
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Quote:
Originally Posted by Sin City View Post
This is what bugs me about software people (and I work with a lot of them).

They like to think they know everything so "choice" is not an option.

"Why should anyone want to change it? It's perfect the way I designed it!"
Agreed. That's why I'm going aftermarket. Clean and simple. No entanglement with car's software, electronics.
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Old 07-13-2014, 08:42 PM   #10
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Originally Posted by mkr1966 View Post
On the M7, leave out of eco and AFM never works. Auto I think your screwed.
For the auto, use sport or track, and the manual trans mode and you are good to go.
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Old 07-13-2014, 10:47 PM   #11
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Old 07-13-2014, 10:50 PM   #12
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Quote:
Originally Posted by mkr1966 View Post
Set to off on setting screen and pull fuse 41(yellow one).
This is the correct answer. ^

Pull fuse 41, flaps never close.
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Old 07-13-2014, 11:33 PM   #13
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You can force the two muffler valve to stay open all the time by setting the correct menu item but that still leaves you with the AFM valves. Two of the flaps are for setting the correct back pressure for four cylinder mode. I personally like getting 33 mpg on the highway trips so I'm not pulling any fuses or using aftermarket exhaust. If you have an automatic you want to keep the exhaust stock of else throw away your warranty and get Active Fuel Management tuned out because AFM is active in all modes and needs the two valves before the mufflers to work right. Not sure about damaging the motor, but the potential to do so is there and I'm sure it will screw up your fuel mixture without the correct back pressure. The two AFM valves are on every C7 made even if you don't have NPP.

Last edited by Klyde; 07-13-2014 at 11:41 PM.
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Old 07-13-2014, 11:41 PM   #14
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Quote:
Originally Posted by Klyde View Post
Two of the flaps are for setting the correct back pressure for four cylinder mode. I personally like getting 33 mpg on the highway trips so I'm not pulling any fuses or using aftermarket exhaust. If you have an automatic you want to keep the exhaust stock of else throw away your warranty and get Active Fuel Management tuned out because AFM is active in all modes and needs the two valves before the mufflers to work right. Not sure about damaging the motor, but the potential to do so is there and I'm sure it will screw up your fuel mixture without the correct back pressure.
Fuse 41 only affects the rearmost flaps, which attenuate sound (NPP - the topic of this thread).

Fuse 32 controls AFM, which the OP was not asking about.

Lastly, the AFM valves are not used for backpressure - the CCM controls these in V4 for (again) additional sound attenuation.

Last edited by Theta; 07-14-2014 at 12:09 AM. Reason: Spelling.
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Old 07-13-2014, 11:44 PM   #15
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Quote:
Originally Posted by Klyde View Post
You can force the two muffler valve to stay open all the time by setting the correct menu item but that still leaves you with the AFM valves.
Additionally, contrary to your belief, the NPP valves will not remain open at all times even with Engine Sound Management turned off.

The only method of leaving these open is removing fuse 41, which is perfectly safe for the vehicle.
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Old 07-13-2014, 11:49 PM   #16
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I watched a video of one of the engineers that designed the AFM system and he stated it was for correct back pressure in four cylinder mode not sound control. He said it was tricky getting everything just right for eight cylinders and also work with only four. The air flow through the system is quite different between the two and is addressed by the AFM valves. There is no need to remove only the fuse for the NPP because you can turn it off in the menu. If you hear a sound difference when NPP is turned off it is the AFM valves doing it. Any one considering getting after market exhaust because they didn't buy the NPP will still have to consider the AFM valves to make the car work correctly. The AFM valves are not for sound control but to tune the exhaust for four cylinder operation.

Theta:
You can do what ever you want to your own car but be careful what you tell others because there is a real chance of screwing up their cars by taking out certain pieces of a very complicated system. I'm just trying to give them as much information as possible so they can make an educated decision about this modification.

Last edited by Klyde; 07-13-2014 at 11:59 PM.
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Old 07-13-2014, 11:59 PM   #17
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Quote:
Originally Posted by Klyde View Post
There is no need to remove only the fuse for the NPP because you can turn it off in the menu.
This is enough to make me pass over your post.

If you're interested in learning instead of pushing incorrect data, refer to the Fuse 41 thread. If you still want to argue, I'll pull the factory electrical schematic sheets that show the tip-in and mode closure.

But hey, what do I know, right?
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Old 07-14-2014, 12:02 AM   #18
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You can pass over all of my post if you want. It's not you I'm trying to show here. I'm stating that the rear valves are deactivated by the menu and you don't have to remove any fuses. There is no reason to pull that fuse. You may if you want to but the NPP valves are turned off by the menu. If you here a sound level change after turning it off in the menu then you are hearing the AFM valves activating.

Last edited by Klyde; 07-14-2014 at 12:05 AM.
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Old 07-14-2014, 12:03 AM   #19
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Quote:
Originally Posted by Klyde View Post
Theta:
You can do what ever you want to your own car but be careful what you tell others because there is a real chance of screwing up their cars by taking out certain pieces of a very complicated system. I'm just trying to give them as much information as possible so they can make an educated decision about this modification.
Hey bud, if you haven't noticed, I know a thing or two around here... Sort of goes with the territory.

I respect your opinion, but you're wrong.

See this thread:

http://forums.corvetteforum.com/c7-t...ck-result.html

Now you could apologize, or just act like every other *** on this forum that wants to be right. They don't let me post incorrect information just for the hell of it around here...
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Old 07-14-2014, 12:03 AM   #20
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Quote:
Originally Posted by Klyde View Post
I'm stating that the rear valves are deactivated by the menu and you don't have to remove any fuses. There is no reason to pull that fuse. You may if you want to but the NPP valves are turned off by the menu. If you here a sound level change after turning it off in the menu then you are hearing the AFM valves activating.
Incorrect. See above... You just don't realize that you're wrong. You still are, but you'd still rather fight than learn.

Read the thread, and then either come back and argue more, or apologize. If you do choose to argue, I'd love to see your explanation of the sound difference for all of us without AFM enabled.

Last edited by Theta; 07-14-2014 at 12:33 AM.
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Old 07-14-2014, 12:03 AM
 
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