NPP won’t work?

19Nasty1le · 09-08-2025, 03:05 PM

Just swapped my Corsa Extreme+ system for the Corsa NPP axelback to quiet the car down a bit after mods but the valves are just staying wide open they don’t respond to any mode selection. Has anyone had this happen before by chance when going back to a NPP exhaust?

I’ve asked the tuner, they claim it’s not shut off or tuned out. I don’t have a unlocked MVPI tool, is it accessible without unlocking again does anyone know? I’ve checked the fuses and the wires are all plugged in but the motors never spin, even tried another set of actuators.

PFA

calypso50kid · 09-09-2025, 12:55 PM

did you go into the setting on the radio home screen and go to the driving modes and change it to auto where it will change with the modes on the center console? someone may have changed it to be in track all the time.

2023_ZL1-AUTO · 09-09-2025, 01:26 PM

If I remember correctly, and I could be 100% WRONG. I think this happen when I installed my Corsa Xtreme, the actual valves where in the opposite position when I installed the NPP actuator / controller on the muffler. I removed the NPP, changed the position and then reinstalled?

ZLRob · 09-09-2025, 10:34 PM

This is probably a really really stupid question, but I've got to rule it out anyway since your stuff is not working. Did you make sure your actuators are even plugged in? I had an issue with one of my exhausts where the smoothbrain who did the work for me forgot to plug it in and I didn't catch it until I was home staring at the setup wondering why it wouldn't shut up despite attempts to put it in stealth mode.

WhiteMale · 09-10-2025, 06:38 AM

check fuse 50 or 51 that isn't blown or removed. I can't recall the exact fuse number the NPP is on.

2SS Capt · 09-10-2025, 12:20 PM

Quote:

Originally Posted by WhiteMale

check fuse 50 or 51 that isn't blown or removed. I can't recall the exact fuse number the NPP is on.

I think it is 51...

19Nasty1le · 09-11-2025, 06:00 PM

So I checked… I was looking at 43 because I saw Exh Vlv lol 51 was missing so tossed a 15 in but now when I turn the car to ACC (to move valves before car starts) it sounds like this until I select “stealth” on the touch screen

https://youtube.com/shorts/k56SOEE6q...drb3G_-WLCdpmf

09-08-2025, 03:05 PM	#1
19Nasty1le Craig Drives: 2019 ZL1 1LE Join Date: Jan 2019 Location: Peterborough, ON Canada Posts: 443	NPP won’t work? Just swapped my Corsa Extreme+ system for the Corsa NPP axelback to quiet the car down a bit after mods but the valves are just staying wide open they don’t respond to any mode selection. Has anyone had this happen before by chance when going back to a NPP exhaust? I’ve asked the tuner, they claim it’s not shut off or tuned out. I don’t have a unlocked MVPI tool, is it accessible without unlocking again does anyone know? I’ve checked the fuses and the wires are all plugged in but the motors never spin, even tried another set of actuators. PFA Attached Images __________________

09-09-2025, 12:55 PM	#2
calypso50kid Drives: 2018 zle, 03 cobra, 92 mustang lx Join Date: Oct 2024 Location: greenville, sc Posts: 56	did you go into the setting on the radio home screen and go to the driving modes and change it to auto where it will change with the modes on the center console? someone may have changed it to be in track all the time. __________________ Owner and driver of the worlds fastest naturally aspirated drag radial car. Hays Consulting and Performance 4.58@151 BBC powered 585 ci 9000+ rpm https://youtu.be/wSz2OedlNSI?si=SnPoqreXFQ7NLYX8 2018 ZL1 1LE 416ci LME long block, 2650, reflex port injection, full e85, tick performance tr6060, monster triple disc, DSS drive shaft, g force axles.

09-09-2025, 01:26 PM	#3
2023_ZL1-AUTO Drives: 2023 ZL1 Join Date: Dec 2022 Location: Columbus, Ohio Posts: 1,287	If I remember correctly, and I could be 100% WRONG. I think this happen when I installed my Corsa Xtreme, the actual valves where in the opposite position when I installed the NPP actuator / controller on the muffler. I removed the NPP, changed the position and then reinstalled? __________________ Katech Track Day CAM 38%•BTR Dual Valve Springs•Johnson Lifters•Trend 3/8 Chromoly Pushrods• VVT Del•CNC Heads•AFM Delete• C5-R Timing Chain•Katech Oil Pump•Katech 112mm•Maggie 2650 3.25” Upper/ATI SD w/10.32” +20%•10 Rib Belt•RFBG•FI IC Stage 2•THPSI Port w/875cc Inj•Katech Dual Fuel Pump•DSX Aux Pump•SW 2" Headers w/Legend NPP•GESI UHO 4.5" CATs•Brisk RR14S Plugs•BMR Motor Mounts•BMR Cradle Lockout &Bushings Kit•BMR Rear Suspension & 15" Conversion•DSS 1pc DS•RPM 6-Point Roll Cage•10lb FireSense+ w/4Fire SFI 17.1 Fire Sys•Weld Forged Vitesse Rear 17x10 Beadlocks-Front 18x6•Unlocked TCM

09-09-2025, 10:34 PM	#4
ZLRob Super Stock Drives: Chevrolet Camaro ZL1 Join Date: May 2022 Location: Concordia Posts: 1,004	This is probably a really really stupid question, but I've got to rule it out anyway since your stuff is not working. Did you make sure your actuators are even plugged in? I had an issue with one of my exhausts where the smoothbrain who did the work for me forgot to plug it in and I didn't catch it until I was home staring at the setup wondering why it wouldn't shut up despite attempts to put it in stealth mode. __________________ 2017 Red Hot ZL1 A10 - Apex ARC-8's, 305/ 325 PS4's, DSX 9.06 12% lower, Griptec OE upper, NGK HR7 Ruthenium plugs, Nostrum 25+ injectors, XDI Goliath HPFP, Katech dual in tank LPFP, Katech oil pump, LME tensioner, DOD delete, LT1 big fuel cam, Jokerz ported blower, MPI lid, GMS hood extractor bracket, Granatelli SS plug wires, Cordes LTR reservoir, DMS T-stat housing, 186* LS3 T-stat, Borla X pipe, Black Widow Angry Housewife/ Corsa NPP mufflers, BMR engine mounts, Banks iDash, Lithium Battery, AEM X- Series, HP Tuners, E85, 16.5 psi 758 HP/ 804 TQ Last edited by ZLRob; 09-10-2025 at 08:35 PM.

09-11-2025, 06:00 PM	#7
19Nasty1le Craig Drives: 2019 ZL1 1LE Join Date: Jan 2019 Location: Peterborough, ON Canada Posts: 443	So I checked… I was looking at 43 because I saw Exh Vlv lol 51 was missing so tossed a 15 in but now when I turn the car to ACC (to move valves before car starts) it sounds like this until I select “stealth” on the touch screen https://youtube.com/shorts/k56SOEE6q...drb3G_-WLCdpmf __________________

09-10-2025, 06:38 AM	#5
WhiteMale Drives: 23 ZL1 A10 Rapid Blue Join Date: Aug 2020 Location: MO Posts: 2,260	check fuse 50 or 51 that isn't blown or removed. I can't recall the exact fuse number the NPP is on.

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