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Old 03-30-2018, 01:02 PM   #1
metrogdor22
 
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Can I restore NPP exhaust functionality with a tune?

I'm going to say something I never thought I would: My car is too loud. After getting offroad headers and a cam, I need to quiet it down, at least in the mornings. My car is equipped with the factory NPP exhaust, but the previous owner did something to keep them open. The only way I know of to do this is by pulling fuse F8 in the trunk fuse box. I checked today, and that fuse is still there. Did the previous owner do something else to keep it open? Maybe a tune? Can I get it retuned to restore that to factory functionality?
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Old 03-30-2018, 01:11 PM   #2
1911 1LE
 
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Try pressing the garage door buttons with the car idling and see if it quiets down with one of them. That's how I have mine.G/L
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Old 03-30-2018, 01:14 PM   #3
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Originally Posted by 1911 1LE View Post
Try pressing the garage door buttons with the car idling and see if it quiets down with one of them. That's how I have mine.G/L
Thanks for the suggestion. No luck. That's how I'd like to have it setup though.
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Old 03-30-2018, 01:47 PM   #4
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Have you pulled fuse 8 to see if there is any difference?
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Old 03-30-2018, 02:17 PM   #5
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Under normal operation, the flaps will stay open at idle unless you wire a three-position switch to force them closed.
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Old 03-30-2018, 02:31 PM   #6
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Originally Posted by larry_g View Post
Under normal operation, the flaps will stay open at idle unless you wire a three-position switch to force them closed.
What? I thought they were closed at idle and opened up at 3k RPM. Isn't the purpose to keep it quite when you start it in the morning, or in a neighborhood?
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Old 03-30-2018, 02:38 PM   #7
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Order the Forza 3 way controller and program it to the garage buttons
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Old 03-30-2018, 02:46 PM   #8
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Originally Posted by metrogdor22 View Post
What? I thought they were closed at idle and opened up at 3k RPM. Isn't the purpose to keep it quite when you start it in the morning, or in a neighborhood?
NPP is OPEN at idle and closes when the vehicle starts to accelerate until around 3500 rpm then it opens again.
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Old 03-30-2018, 02:52 PM   #9
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NPP is OPEN at idle and closes when the vehicle starts to accelerate until around 3500 rpm then it opens again.
Yep what he said. Open at idle and closes on mine about 15-20 MPH at slow accelerations. Get on it and it opens. Get the Forza 3 way and in the morning you can close the flap and open it when you want or select the factory setting. The only time I close mine is startup in the morning and If I have the backseat down sometimes you can hear drone. You can look in the pipe and see if the flap is closed.
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Old 03-30-2018, 03:13 PM   #10
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I wired in my own three position switch following this diagram...

http://www.camaro5.com/forums/showpo...44&postcount=9
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Old 03-30-2018, 03:28 PM   #11
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Originally Posted by metrogdor22 View Post
What? I thought they were closed at idle and opened up at 3k RPM. Isn't the purpose to keep it quite when you start it in the morning, or in a neighborhood?
Corvette system was designed differently than the Camaro system.

if you want the system to function like the Corvette system then you can run your own vacuum lines and use a C3 Corvette headlight switch to control it all.
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Old 03-30-2018, 10:07 PM   #12
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Or add cats....
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Old 03-31-2018, 03:38 AM   #13
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Or add cats....
Hell no lol
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Old 03-31-2018, 06:09 AM   #14
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Quote:
Originally Posted by metrogdor22 View Post
I'm going to say something I never thought I would: My car is too loud. After getting offroad headers and a cam, I need to quiet it down, at least in the mornings. My car is equipped with the factory NPP exhaust, but the previous owner did something to keep them open. The only way I know of to do this is by pulling fuse F8 in the trunk fuse box. I checked today, and that fuse is still there. Did the previous owner do something else to keep it open? Maybe a tune? Can I get it retuned to restore that to factory functionality?
Don’t know about a tune controlling the NPP but I’m going to guess no. Couple of other thoughts. Is the fuse good? Check out a Dashlogic OBD2 unit. In addition to displaying PID info onto the DIC, HUD or Mylink screen it also controls NPP operation ( stock, always open, always closed) NO wiring required, you just use the cruise control button like a toggle switch.
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