[Norm]

Have the NPP programmed for continuous open, however, when going through the gears (A6, S or Tr)) it closes in 3rd gear, until I give it a little gas, then it will open and stay open through the rest of the gears. Anyone else experience that? Is there a fix? Thanks.

 

[Chip]

The only way you can disable the NPP is to pull a fuse. I believe it was fuse # 41, but need to have that confirmed.

 

[jsvette]

How do you know your NPP is closing when you go into 3rd? Even with the NPP set to be 'always open' you will only hear a difference (that is, significant increase in its loudness) when you are accelerating/stepping on the gas. Otherwise even with it open, it will settle down into a relatively quite mode, such as when you are cruising at highway speeds until you step on the gas.

 

[Boomer]

Have the NPP programmed for continuous open, however, when going through the gears (A6, S or Tr)) it closes in 3rd gear, until I give it a little gas, then it will open and stay open through the rest of the gears. Anyone else experience that? Is there a fix? Thanks.

Its probably the AFM kicking in. Sounds like your doing a gradual pick up in speed. I have my A6 programed the same way. Somebody did make a good case in this Forum that the NPP still closes in some cases even though programed off.

 

[regguy1]

My 7 MT stays open 100% of the time in Track Mode, in sport it will close at higher speed / rpm

 

[Chip]

The only way you can disable the NPP is to pull a fuse. I believe it was fuse # 41

Never mind, doing so will throw a code.

 

[jsvette]

I believe there appears to be some confusion in this thread: with the NPP you have one of two settings as options in personalizing your preferences on your Stingray. You can have NPP set to "Auto" which means that the valves are controlled by (linked to) the Mode you have selected, ie: eco, tour, sport, track and each in turn controls the valves differently resulting in a audible difference between relatively quiet and authoritatively loud in combination of your current throttle position but dependent on the drive Mode. Or you can have NPP set to "Auto Off," which means the valves are set to be open at all times, resulting in an audible difference between relatively quiet and authoritatively loud solely dependent on your current throttle position independent (or regardless) of your drive Mode setting. I seriously doubt you can 'feel' the valves open or close but you can definitely hear the difference, and of course, if you are behind a Stingray at exhaust eye level, you can actually see the valves open or close.

 

[Norm]

When I slowly progress through the gears starting with first, the exhaust is open, when it hits third, I hear a phoomp, gets totally quiet, while still keeping the same foot pressure, in about two to three seconds it opens back up as before. Is it something to be concerned about or just put up with it. Heavy pedal, no issues, just light pressure on the pedal.

 

[jsvette]

Norm someone with a manual will have to try duplicating your experience. Mine is an auto.

 

[Boomer]

When I slowly progress through the gears starting with first, the exhaust is open, when it hits third, I hear a phoomp, gets totally quiet, while still keeping the same foot pressure, in about two to three seconds it opens back up as before. Is it something to be concerned about or just put up with it. Heavy pedal, no issues, just light pressure on the pedal.

Its the AFM. Program your DIC to show when you go V4 vs V8.

 

[Norm]

Thanks guys.

 

[Dasyatis]

There also seems to be an rpm threshold where if you are below around 1400 is switched to a quieter mode, no doubt due to a droning effect if fully open. What rpm to you hit when you first shift into third?

 

[Lipstic]

Never mind, doing so will throw a code.

So pulling fuse 41, throws a code? I must have missed that information.


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[Chip]

So pulling fuse 41, throws a code? I must have missed that information.


Sent from my iPhone using Corvette Stingray Forum

Rebecca; I posted that response after I was told that it did, but I later found out that both fuses (#41 & #32) were pulled and that having both fuses pulled does cause a CEL. I am now awaiting some more info. regarding just the #41 fuse being pulled. I'll repost if pulling the single fuse goes un-noticed by the ECM's. AKA "Hal"

 

[Norm]

There also seems to be an rpm threshold where if you are below around 1400 is switched to a quieter mode, no doubt due to a droning effect if fully open. What rpm to you hit when you first shift into third?

Right around 1400. When I keep more pressure on the pedal (naturally goes faster) I don't hear it closing, keeps a constant drone. This closing only happens when I'm proceeding through the gears (A6) using just the slightest foot pressure (like taking off slow) and proceeding slow through the gears.

I went into the DIC and observed the ACM moving from V4 to V8 and back but did not find a source to disable the V4 mode.......do-able???? Thanks.

 

[Chip]

Rebecca; I posted that response after I was told that it did, but I later found out that both fuses (#41 & #32) were pulled and that having both fuses pulled does cause a CEL. I am now awaiting some more info. regarding just the #41 fuse being pulled. I'll repost if pulling the single fuse goes un-noticed by the ECM's. AKA "Hal"

JCobalt has been doing some experimental work with the fuse issue and has reported to me that with only #41 pulled (so far) there has been no CEL indicated on the dash. He has not put on a lot of mileage since doing this, so the jury is still out. I'll report back is their are other developments.

 

[Boomer]

Right around 1400. When I keep more pressure on the pedal (naturally goes faster) I don't hear it closing, keeps a constant drone. This closing only happens when I'm proceeding through the gears (A6) using just the slightest foot pressure (like taking off slow) and proceeding slow through the gears.

I went into the DIC and observed the ACM moving from V4 to V8 and back but did not find a source to disable the V4 mode.......do-able???? Thanks.

Norm:

Glad you got ur DIC set up for this. Do you attribute it to AFM malfunction? The only "drone" I hear is when I'm on the interstate and let the cruise control take me from 55 to 75 and thats just performance. Just like when you "keep more pressure on the pedal". You don't want to disable it. If you do, use the paddle shifts. Your car sounds like it is operating normally!

Side note: I wouldn't mess with fuses unless necessary.

 

[luky7]

When I slowly progress through the gears starting with first, the exhaust is open, when it hits third, I hear a phoomp, gets totally quiet, while still keeping the same foot pressure, in about two to three seconds it opens back up as before. Is it something to be concerned about or just put up with it. Heavy pedal, no issues, just light pressure on the pedal.

Norm,
Mine does the same exact thing
If you figure it out keep me posted

 

[Boomer]

Norm,
Mine does the same exact thing
If you figure it out keep me posted

Its normal. Its the AFM.

 

[AFVETTE]

You can't disable AFM unless you go to an aftermarket solution like RANGE V8 or a "tune" like Diablo. That's my plan.