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NPP fuse

Old 07-12-2018, 06:16 PM
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vettez51zo6
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Default NPP fuse

can you pull the npp exhaust fuse on a 2019 zo6 8 speed auto as you can on an 17/18 grand sport ???
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Old 07-12-2018, 07:55 PM
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Yes it is fuse #87, I pulled it on my 2019 no issues great sound.
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Old 07-12-2018, 08:39 PM
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Thank you dvilin for the quick info reply.
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Old 07-12-2018, 09:17 PM
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Originally Posted by vettez51zo6 View Post
Thank you dvilin for the quick info reply.
whats the difference in pulling the fuse versus just putting it in track mode ?

my m7 stays in track mode even after you stop and start it
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Old 07-12-2018, 10:02 PM
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Originally Posted by Mr. Gizmo View Post


whats the difference in pulling the fuse versus just putting it in track mode ?

my m7 stays in track mode even after you stop and start it
Even in track mode the flaps adjust/ close, pull the fuse they are always open. Haven't tried in my 17 yet fuse #in the 17 anyone?
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Old 07-12-2018, 10:39 PM
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Originally Posted by cheapthrills View Post
Even in track mode the flaps adjust/ close, pull the fuse they are always open. Haven't tried in my 17 yet fuse #in the 17 anyone?
That is another C7 myth. Clearly states in the FSM the valves stay open all the time in track mode. Mine stay open from idle all the way to red line no matter what the throttle setting. The only time they close is when the engine is running in 4 cylinder mode and you don't want them open then anyways. I can tell when my car switches from V8 to V4 as the exhaust switches from loud to quiet at 1200 rpm and then from quiet to loud at 1200 rpm as the throttle is opened to go up a hill or something and the engine switches back to V8 mode.

See second page of explanation from FSM below:



That is just about as clear of a statement that GM can make about the valves. No need to pull the fuse.
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Old 07-13-2018, 09:02 AM
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^^^^ Well you and your interpretation of the manual are wrong. The NPP valves DO NOT Stay open 100% of the time they will close at certain rpms.
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Old 07-13-2018, 10:39 AM
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Originally Posted by dvilin View Post
^^^^ Well you and your interpretation of the manual are wrong. The NPP valves DO NOT Stay open 100% of the time they will close at certain rpms.
Correct even in track mode the valves on my car also did not remain open 100% of the time. I chose the mild/wild option however over just pulling the fuse.
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Old 07-13-2018, 11:41 AM
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Originally Posted by dvilin View Post
^^^^ Well you and your interpretation of the manual are wrong. The NPP valves DO NOT Stay open 100% of the time they will close at certain rpms.
The "see note above" is missing from his picture. I know from experience in my Z51 it makes a difference. I have not tried in my Z06 so leave that to those who have.

Last edited by cheapthrills; 07-13-2018 at 11:42 AM.
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Old 07-13-2018, 03:28 PM
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Originally Posted by dvilin View Post
^^^^ Well you and your interpretation of the manual are wrong. The NPP valves DO NOT Stay open 100% of the time they will close at certain rpms.
Well I can hear change exhaust tone when the engine switches from V8 to V4 and back again. They are open at idle in Sport and Track and not tour just like the FSM says. If I drive the car in Tour mode they stay open all the time from idle at a traffic light all the way to max rpm at wide open throttle. They are open at very low rpms just running along at 50 mph in 6th. I can definitely hear them. I don't have a camera that can shoot inside the pipes while the car is moving but I know they are open. The book says so, my ears as bad as they are say so and the color of the exhaust pipe says so. The outer pipes are pitch black except where they turned red from the last track day that I ran. Just because you think the sound is muffled at low rpms doesn't mean it is. You don't need to pull that fuse no matter what the internet has told you. It isn't a C6 NPP exhaust.

Bill
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Old 07-14-2018, 03:46 PM
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Originally Posted by Bill Dearborn View Post
Just because you think the sound is muffled at low rpms doesn't mean it is. You don't need to pull that fuse no matter what the internet has told you. It isn't a C6 NPP exhaust.

Bill
Good luck trying to convince the doubters, Bill. I've tried and tried. They simply refuse to believe it.

Montana Bob
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Old 07-14-2018, 04:18 PM
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A camera setup would prove it. Wish I had a gopro.
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Old 07-14-2018, 04:19 PM
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Hello corvette friends, I just bought a 2019 zo6 and in the rear hatch is a clear plastic bag inside the bag are cold air brake ducts my dealer told me they won't install them because they said the ducts are for track use only. any thoughts on this subject ???
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Old 07-14-2018, 06:53 PM
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Originally Posted by vettez51zo6 View Post
Hello corvette friends, I just bought a 2019 zo6 and in the rear hatch is a clear plastic bag inside the bag are cold air brake ducts my dealer told me they won't install them because they said the ducts are for track use only. any thoughts on this subject ???
The dealer is correct.
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Old 07-14-2018, 07:52 PM
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Originally Posted by Bill Dearborn View Post
They are open at idle in Sport and Track and not tour just like the FSM says. If I drive the car in Tour mode they stay open all the time from idle at a traffic light all the way to max rpm at wide open throttle. They are open at very low rpms just running along at 50 mph in 6th.

Bill
My car (100% stock) is different.

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Old 07-14-2018, 10:12 PM
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Originally Posted by Warp Factor View Post
My car (100% stock) is different.
Do you have somebody riding behind your car checking the valves while you are driving? I can hear my exhaust and when the engine switches to V4 there is a noticeable cut in exhaust noise ( which matches what the note referenced in the FSM indicates). Put the car in Tour Mode where it doesn't switch into ECO mode and the exhaust is open all the time. If you have an A8 where it switches to V4 in Tour Mode what you might be hearing is the valves closing when it swtiches. Pulling the fuse just makes it worse if that is the case. The exhaust sounds terrible in V4 mode if the valves are open.

Bill
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Old 07-14-2018, 10:26 PM
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In normal driving without Performance Shift when I let off the throttle in Sport mode, the valves will close. When your not heavy on the throttle when you let off approaching a traffic light, I believe they close some, if not all the way. I feel like they are programmed more to throttle position. However, when your on it in Performance Shift they’ll stay open under engine braking. I have an A8.
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Old 07-14-2018, 11:13 PM
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Originally Posted by jlbjr View Post
In normal driving without Performance Shift when I let off the throttle in Sport mode, the valves will close. When your not heavy on the throttle when you let off approaching a traffic light, I believe they close some, if not all the way. I feel like they are programmed more to throttle position. However, when your on it in Performance Shift they’ll stay open under engine braking. I have an A8.
I have an M7 and they are open all the time on throttle or off throttle except when the drive mode is set in ECO mode and the engine happens to be in V4 mode. Do you have Engine Sound Management set in the permanent Track Mode setting? When the exhaust is set in Track Mode you shouldn't be able to tell the difference (other than during V4 operation when the exhaust should get quiet) between Weather, Eco, Tour, Sport or Track driving modes.
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Old 07-14-2018, 11:35 PM
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I don’t do track mode too much because of the ride. It makes sense that the valves should just be wide open in track. My theory is I had both valve actuators fail. When the valves were closed in tour mode the valves made a hideous clicking noise. When the valves were open, no noise. So when I drove around in the different modes I could tell when they were in the closed position. In sport coasting off throttle the valves were closing because the noise was there. I didn’t try track.
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Old 07-15-2018, 12:13 AM
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Originally Posted by MontanaBob View Post
Good luck trying to convince the doubters, Bill. I've tried and tried. They simply refuse to believe it.

Montana Bob
Maybe there's something with the M7 and A8s... My car is procharged, cammed, tubes etc... In track mode you could CLEARLY hear the car close the valves. While crusing at certain RPMs. There's no mistaking or need for some one to be looking down the damn pipes to verify.
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