Npp open time

ender2664 · 05-26-2016, 08:16 PM

I have read some threads about pulling the fuse vs track and have one question:
How quickly does the valve open?
I assume when I'm sitting at a light in track mode the valve is closed. If I Rev at a car while at the light does the valve open quickly enough so exhaust will be heard as open? Or does the valve not open that quick?

raptor5244 · 05-26-2016, 10:54 PM

The NPP valves are pretty much wide open in Track and Sport mode while at idle. You will definitely hear the exhaust as you accelerate from a stop. They tend to close up when you are just cruising at low rpm at idle. If you pull the fuse they never close up.

JFM-jr · 05-27-2016, 11:36 AM

It closes in track mode at partial throttle at highway speeds. It is open when at idle the area you will notice the fuse pulled is when on the highway cruising. You will be able to hear the AFM valves opening and closing alot better as well if your an automatic.

Techn9cian805 · 05-27-2016, 11:43 AM

just pull the fuse and enjoy. there is not con to doing so. but be sure its in track mode when you do the fuse pull, if you pull the fuse in tour/stealth, the valves will be closed only.

Modshack · 05-27-2016, 12:29 PM

Quote:

Originally Posted by Techn9cian805

when you do the fuse pull, if you pull the fuse in tour/stealth, the valves will be closed only.

Not my experience. The default for the valves is OPEN. It's the algorithm in whatever mode you're in that closes them. That requires power (fuse in)

Dmagg0802 · 06-01-2016, 01:55 PM

Pull fuse while car is running or off?

Richard0nee · 06-01-2016, 02:17 PM

Quote:

Originally Posted by Dmagg0802

Pull fuse while car is running or off?

Make sure the car is turned off.

I have my fuse pull, love it! And the valve still stay open FOREVER lol

You can try toggling all the track modes, no difference in sound and you know that you will have the loudest sound available.

It's really only loud the first minute or two upon a cold start up... then it'l ease down and stay that way.

obarry13 · 06-02-2016, 10:21 AM

I have one question with this, doesn't the valve have to do with your mpg or is that all to do with the engine? Only reason I ask is every time the vehicle changes from V8 to V4 mode, the valve closes as well, which would mean a difference of 17mpg to 32mpg on the highway.

raptor5244 · 06-02-2016, 12:20 PM

Quote:

Originally Posted by obarry13

I have one question with this, doesn't the valve have to do with your mpg or is that all to do with the engine? Only reason I ask is every time the vehicle changes from V8 to V4 mode, the valve closes as well, which would mean a difference of 17mpg to 32mpg on the highway.

Nothing. The auto transmission Camaros with NPP have an extra set of valves in the exhaust that only activate when you are in AFM (V4 mode). The point of these AFM NPP valves is to eliminate the undesirable exhaust note when in V4 mode.

The Gen5 Camaros with auto trans got the L99 motor and did not have NPP as an option. This was one of the main reasons. No AFM valves to control the V4 mode exhaust note. So, folks usually had to tune out AFM on the L99s if they wanted an aftermarket exhaust to sound good all the time. The LS3 in the manual tranny Gen5s did not have this issue since there was no AFM to speak of on the LS3. The difference though was that the LS3 based NPP exhaust used vacuum control to close the valves instead of the electronic controlled valves on the Gen 6 NPP. On the Gen5 LS3 manual cars the NPP valves would be open at idle and then would close at low and cruising RPM but once you put your foot in it at about 3000rpm or so they would open up again to redline. Some like to pull the fuse even on the GEN5 NPP cars so that is was louder in that 1500-3000rpm range.

The GEN6 NPP offers more control with the settings with Stealth, Tour, Sport and Track. These profiles basically control how much and how long the rear NPP valves stay open. If you pull the fuse the rear NPP valves never close but the AFM valves to stay in sync with AFM mode. I am doing this now on my car since the darn NPP rattles on me in the other modes. If I keep the fuse pulled it work pretty good for me with the A8 since the AFM will kick in while cruising and the exhaust will be quiet but once I get on it it roars to life.

Once I get confirmation that there is a real fix or new design of the rattling NPP I will take it in to get it fixed/replaced.

obarry13 · 06-02-2016, 01:33 PM

Quote:

Originally Posted by raptor5244

Nothing. The auto transmission Camaros with NPP have an extra set of valves in the exhaust that only activate when you are in AFM (V4 mode). The point of these AFM NPP valves is to eliminate the undesirable exhaust note when in V4 mode.

The Gen5 Camaros with auto trans got the L99 motor and did not have NPP as an option. This was one of the main reasons. No AFM valves to control the V4 mode exhaust note. So, folks usually had to tune out AFM on the L99s if they wanted an aftermarket exhaust to sound good all the time. The LS3 in the manual tranny Gen5s did not have this issue since there was no AFM to speak of on the LS3. The difference though was that the LS3 based NPP exhaust used vacuum control to close the valves instead of the electronic controlled valves on the Gen 6 NPP. On the Gen5 LS3 manual cars the NPP valves would be open at idle and then would close at low and cruising RPM but once you put your foot in it at about 3000rpm or so they would open up again to redline. Some like to pull the fuse even on the GEN5 NPP cars so that is was louder in that 1500-3000rpm range.

The GEN6 NPP offers more control with the settings with Stealth, Tour, Sport and Track. These profiles basically control how much and how long the rear NPP valves stay open. If you pull the fuse the rear NPP valves never close but the AFM valves to stay in sync with AFM mode. I am doing this now on my car since the darn NPP rattles on me in the other modes. If I keep the fuse pulled it work pretty good for me with the A8 since the AFM will kick in while cruising and the exhaust will be quiet but once I get on it it roars to life.

Once I get confirmation that there is a real fix or new design of the rattling NPP I will take it in to get it fixed/replaced.

Gotcha that makes sense. So the chirping valve when my car changes from V8 to V4 would be the AFM valves then? Brought it in to be fixed a month ago and all they did was lube it and it is chirping again.

raptor5244 · 06-02-2016, 07:45 PM

Quote:

Originally Posted by obarry13

Gotcha that makes sense. So the chirping valve when my car changes from V8 to V4 would be the AFM valves then? Brought it in to be fixed a month ago and all they did was lube it and it is chirping again.

Does it chirp with the rear NPP Fuse pulled? Fuse 51. If so, then the only valves that can move are the AFM NPP valves, There is a fuse for the AFM NPP valves as well that you can pull if you wanted to verify but I heard that will throw a check engine light if you pull it. I saw the TSB that says to spray the Dry Slide lubricant in the NPP valve assembly...annoying for sure.

obarry13 · 06-06-2016, 02:55 PM

Quote:

Originally Posted by raptor5244

Does it chirp with the rear NPP Fuse pulled? Fuse 51. If so, then the only valves that can move are the AFM NPP valves, There is a fuse for the AFM NPP valves as well that you can pull if you wanted to verify but I heard that will throw a check engine light if you pull it. I saw the TSB that says to spray the Dry Slide lubricant in the NPP valve assembly...annoying for sure.

So I pulled Fuse 51 this weekend. It is definitely the AFM valves that are causing the squeak/chirp when it switches from V8 to V4. I have to say, I am loving the sound while driving/coasting now though!

ReFLeX135 · 06-06-2016, 07:08 PM

Quote:

Originally Posted by obarry13

So I pulled Fuse 51 this weekend. It is definitely the AFM valves that are causing the squeak/chirp when it switches from V8 to V4. I have to say, I am loving the sound while driving/coasting now though!

I noticed this same exact situation occurring, and pulled the fuse too. It occurs from V8 to V4 still. However, I noticed that, when going around 25 mph in 3rd gear (auto shifts to 3rd at this speed), if I slow and down shift into 2nd manually I can reproduce this chirp. Makes me wonder what's really going on.

mojman2001 · 08-28-2016, 06:52 PM

To me I've notice the clutch is more responsive in track and sports mode or is it just me? But my question is does the m6 have afm valves? Or is just automatics? 2. Whats the best exhaust with aggressive sound to it. I have my eye on blackheart hookers, but i wish Masterflow would make npp exhaust for the outlaw series. I had that on my 2013 ss love the sound to it and it was aggressive, but loud. That was stock headers and cats..

05-26-2016, 08:16 PM	#1
ender2664 Account Suspended Drives: 2016 2SS Join Date: Mar 2014 Location: Palm Desert Posts: 2,353	Npp open time I have read some threads about pulling the fuse vs track and have one question: How quickly does the valve open? I assume when I'm sitting at a light in track mode the valve is closed. If I Rev at a car while at the light does the valve open quickly enough so exhaust will be heard as open? Or does the valve not open that quick?

05-27-2016, 11:36 AM	#3
JFM-jr Drives: 2016 Camaro 2SS Join Date: Mar 2016 Location: Suffolk Long Island Posts: 954	It closes in track mode at partial throttle at highway speeds. It is open when at idle the area you will notice the fuse pulled is when on the highway cruising. You will be able to hear the AFM valves opening and closing alot better as well if your an automatic. __________________ 2016 Hyper Blue 2SS A8,NPP,Moonroof Pray ported factory intake manifold Ported TB Rotofab ARH 1 7/8 longtubes hi flow cats AFM deleted E85 11.0@124.9 11.65@118.8 pump gas,stock tune/exhaust New combo: Pray Performance Heads/cam MSD intake manifold and Circle D 3C 554/491 on E85 all work & tuning done by Pray

05-27-2016, 11:43 AM	#4
Techn9cian805 The BEAST Drives: '16 2SS, '89 Wife Join Date: May 2015 Location: Central Coast, CA Posts: 2,034 View My Garage	just pull the fuse and enjoy. there is not con to doing so. but be sure its in track mode when you do the fuse pull, if you pull the fuse in tour/stealth, the valves will be closed only. __________________ Scarlet: 3/3/16: 2SS Red Hot, M6, Instagram: @luis_what_it_is

08-28-2016, 06:52 PM	#14
mojman2001 Drives: 2016 Camaro SS2 Join Date: Mar 2016 Location: Missouri Posts: 28 View My Garage	NPP Exhaust To me I've notice the clutch is more responsive in track and sports mode or is it just me? But my question is does the m6 have afm valves? Or is just automatics? 2. Whats the best exhaust with aggressive sound to it. I have my eye on blackheart hookers, but i wish Masterflow would make npp exhaust for the outlaw series. I had that on my 2013 ss love the sound to it and it was aggressive, but loud. That was stock headers and cats..

05-26-2016, 10:54 PM	#2
raptor5244 Drives: 2022 CT4-V Blackwing Join Date: Sep 2013 Location: Florida Posts: 2,723	The NPP valves are pretty much wide open in Track and Sport mode while at idle. You will definitely hear the exhaust as you accelerate from a stop. They tend to close up when you are just cruising at low rpm at idle. If you pull the fuse they never close up.

06-01-2016, 01:55 PM	#6
Dmagg0802 Drives: 1969 Z/28 2013 LT 2016 2SS Join Date: Nov 2015 Location: FL Posts: 48	Pull fuse while car is running or off?

06-02-2016, 10:21 AM	#8
obarry13 Drives: 2016 Camaro 2SS Join Date: Dec 2015 Location: Tampa, FL Posts: 243	I have one question with this, doesn't the valve have to do with your mpg or is that all to do with the engine? Only reason I ask is every time the vehicle changes from V8 to V4 mode, the valve closes as well, which would mean a difference of 17mpg to 32mpg on the highway.

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