Exhaust note at startup
Thread Starter
Pro
Joined: Oct 2008
Posts: 713
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From: Central Va
Exhaust note at startup
When I cold start the GS with NPP, it begins with a great tone, which quickly tones down a bit when a valve closes. I want to murder that valve.
Any solutions other than new exhaust?
Any solutions other than new exhaust?
Drifting
Joined: Aug 2005
Posts: 1,318
Likes: 818
From: Melbourne FL
You can pull the fuse, so the valves won't close. The fuse number depends on the year of the car.
Fuse #41 (2014), #42 (2015 - 2018), #87 (2019). It's labelled "Exhaust Valve 2" in your owner's manual.
Fuse #41 (2014), #42 (2015 - 2018), #87 (2019). It's labelled "Exhaust Valve 2" in your owner's manual.
Last edited by sjw91; Jun 20, 2023 at 05:25 PM.
Instructor
Joined: Jul 2022
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From: Santa Monica, CA
I would add that even with the valves open cold start is still more aggressive.. to my understanding it has something to do with programming the timing to get the cats hot faster for emissions.
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^ This is what I have heard too. The loud bark of the exhaust does not last long.
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Tech Contributor
Joined: Oct 1999
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From: Charlotte, NC (formerly Endicott, NY)
If you have the exhaust set in Track Mode the only time the valves close is when the engine is in 4 cylinder mode. With an M7 you need to be in Eco Mode for the engine to switch or in 5th gear below 35 mph for the valve to close. With an A8 the drive mode can be anything and as long as the transmission is in auto mode the engine will switch. However, when the exhaust is in Track Mode it stays open all the time when the car is idling. When a cold engine is started the fuel flow and timing are set to provide a loud starting noise and then slowly drop off as the engine warms as shown in this video of my car.
Bill
Bill
Drifting
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From: Melbourne FL
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
Cold start does have a different profile in tune to assist with Cat efficiency on startup
Pulling the NPP fuse will have no affect on the sound produced during cold start
Dave
Melting Slicks
Joined: Dec 2017
Posts: 3,489
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From: Columbus Ohio
As others have said, the great sound only lasts for about 5-10 seconds.
My fuse is pulled so I have the exhaust open all of the time, but it never sounds as good as when I start it up.
Darn.
My fuse is pulled so I have the exhaust open all of the time, but it never sounds as good as when I start it up.
Darn.
Le Mans Master
Joined: Sep 2006
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From: Palm Harbor not far from Sebring Florida
St. Jude Donor '11
Oldtimer
You can set the NPP to be open through the Settings selection. First press the settings that will bring a screen and looking for Driving Mode. Select that and you will now see a screen that has Engine Sound Management. You can then select any of the options listed, but most like to slide down to the final selection which is track. However, this will not keep the valves open all the time, but more the n in the factory setting. If you pull the fuse, they will remain open all the time but as mentioned they will never sound like the cold start. The nice thing about using the Engine Management, if you have fussy neighbors before leaving or coming home you can select Stealth mode and they are closed.
Here is a YouTube video that goes over this.
Here is a YouTube video that goes over this.
Burning Brakes
Joined: Jun 2021
Posts: 801
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From: NC
Have the mild2wild setup to my garage door switchs 1&2. Mounted in fuse box and have it powered by the heat seater circuit and grounded inside the fuse box. Nothing to get wet and no wires running in the engine compartment. Doing this, the NPP defaults to whatever the last setting was.I generally leave the NPP open all the time unless I want to not offend my neighbors. Turn it off during state inspection so the loader exhaust does not tip the inspector that I have a catless X-pipe. Wiring scheme is some where on the forum. Works great.
Drifting
Joined: Aug 2005
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From: Melbourne FL
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