[2023_ZL1-AUTO]

So, when I turn down my street, I put my car in Touring mode, NPP closes and the car get's ultra quite. But I noticed every time I start my ZL1 up. It shows touring on the info console, but NPP is wide open (like Sport/Track mode) for the first 10 seconds. Then NPP closes to the quite Touring mode. Is this how it always is, the start up routing? I'm only asking because my ZL1 for 10 seconds with NPP open is enough to wake up my whole block, may be my block and the one next. Thanks for in advance for helping me understand this issue!

[arpad_m]

Yes, the NPP valves are opened on cold start for a short while even in tour mode, my guess is to make sure the pressure from the initial fuel burst to quickly light up the cats is handled without restrictions.

As an alternative, you can go into accessory mode (press the start button without your foot on the brake pedal), set the exhaust mode to Stealth in the infotainment, then start the engine, which will result in the quietest cold start you can get. Sure it's a lot of steps just to start up the car, but may be desirable if you leave at 5:30am for work and your neighbors' kids sleep in bedrooms close enough to your house or apartment.

[ShockingZ]

Yes this is completely normal. Not sure why, but it is.

[Sephx1]

Only the Camaro does this, the Corvette starts with valves closed. It can be programmed to start with the valves closed in HP tuners if you have a tune and don’t mind paying for a few more credits. I think I’m going to do this next time I see my tuner. ZLE with headers and 3” Borla S-type.

[2023_ZL1-AUTO]

Great info guys THANKS ! I have HP Tuners. I also need to learn the infotainment system. I don't even thing I've been in it once! Thanks again !!!

[Kerry]

I have an exhaust controller that will give full control with a small remote. Set it in stealth mode and leave it. It will start with them closed and then just hit the button when u want them open. Hit it again any time to close them. Its a pain to hit all the buttons on the display to get their. Sometimes u want them closed quickly. PM me in interested 50 bucks shipped to the lower 48

[KingLT1]

snow/ice mode is also "stealth" and keeps the valves closed if you want quiet start up.

[WhiteMale]

I fire mine in the garage with the door closed but I'm not so sure how much that really helps at 530AM. I never really saw the big difference in Stealth and Track (open/closed) and chose the MBRP axle back so now it's loud AF on a cold start.

[arpad_m]

Originally Posted by KingLT1

snow/ice mode is also "stealth" and keeps the valves closed if you want quiet start up.

Yeah, but the car doesn't remember this mode, so you can't simply leave it in S/I the night before and still have to do a multi-step "startup dance"...

[KingLT1]

Originally Posted by arpad_m

Yeah, but the car doesn't remember this mode, so you can't simply leave it in S/I the night before and still have to do a multi-step "startup dance"...

I agree...but setting to Snow/Ice for startup is less steps vs locking the exhaust setting to stealth in the infotainment. Then you have to go back in and change it when you want the valves to open with all the modes vs using the console switch to change modes.

[2023_ZL1-AUTO]

Originally Posted by KingLT1

I agree...but setting to Snow/Ice for startup is less steps vs locking the exhaust setting to stealth in the infotainment. Then you have to go back in and change it when you want the valves to open with all the modes vs using the console switch to change modes.

Thanks !!!

[crosive]

going to the infotainment and setting the exhaust to stealth will persist on next startup, just be aware that the car will stay in stealth regardless of what you put the drive mode button on.

you will have to take the exhaust out of stealth if you plan any spirited driving.

I leave my car on stealth, and I have a solenoid to remotely "pull the fuse" after I leave the neighborhood, programmed into my garage door opener.

[2023_ZL1-AUTO]

crosive! Thanks for the idea !!!!!