I just installed the Corsa 14777BLK on my 2017 Z06. The npp valves do not open unless pushed open manually. They will close when commanded to do so but will not reopen. Well they actually open about 1/16 barely move.

I called Corsa and they said the dealer needs to do a npp relearn. Anyone had to do this to fix an npp issue after installation of a new exhaust?

they did seem to work fine for a few operations right after the install but then quit working. Tried to lube them up but no change. Stock npp worked fine just prior to installing.

 

Had an issue with an after market exhaust but just one side. But it was with the AFM valves not sure you can relearn the NPP valves. Unlike the AFM valves there is no feedback of its position to the computers of the NPP valve. It turned out to be the valve was hanging up and moving correctly. A shop with a bidirectional scanner can also do a relearn. But if that does not fix your issue it is most likely the Corsa valves them selves. After receiving a new left side pipe and valve all works normal.

 

Valve relearn isn't uncommon with an aftermarket exhaust. Easy process via the dealer, or if you have a professional scan tool (Autel, TopDon etc)

 

I’ll try the recalibration and keep fingers crossed. I have a bad feeling I may have the old design as I saw no springs. This exhaust had a manufacturing date of 4/6/21 and Corsa told me that would be the new design but I’m thinking not. Anyone have a pic of the springs they added?

 

All I know is that the OEM valves are spring loaded to the open position. That tells me that the actuators have power to close the valves but not to open them. Seems to me that if the aftermarket valves are not spring loaded open, like OEM, they are not going to open.

 

Well, I have seen a set of Akrapovics that are spring loaded that had the same issue so I’m holding out hope. I’ll keep you guys posted. I’m intent on a solution one way or another. The car is at the dealership now for this and other repairs. Once solved I’ll report back. I’m guessing there are guys out there with the issue or those that fixed it but have not chimed in yet.

 

Do not overtighten the NPP actuator motors to the Valves or it can add too much resistance to the motor, which can cause it to need to be recalibrated. Use red locktite on the NPP bolts and only use about 5 lbft of torque when you tighten them. For those of you without small torque wrenches, 5 lbft is only the force of a semi firm handshake.

 

Might want to actually us an in-lb torque wrench for that low of a torque. I believe the value in in-lbs would be 5x12 = 60 in-lbs. I wrench my mountain bikes and many of the values are in this range so I have an in-lb torque wrench for this. My seat dropper seat post clamp has to be no more than 50 in-lbs or the spring actuated seat dropper will stick in the down position. Similar situation.

 

I was very cautious not to make the actuator bolts too tight. It’s a great suggestion though as that certainly could cause issues.

 

I'm sure you've double checked the connectors to make sure they're seated tight? Maybe they were loosened with the install.

 

yes, I did double check connections. I think it’s going to come down to the npp relearn or that I actually have the old Corsa design.
I keep kicking myself for not testing for the spring action on the valves before I installed this. I would have to take the rear end off again to remove the actuator and test. I didn’t have time to do that before taking to the dealer for what is likely my second torque tube issue.
I have done that 6 times now with 3 different corvettes so it’s pretty easy compared to the first time I just don’t have the car. Last time was more challenging though as I’m recovering from knee surgery and I was rushed for time on the lift.
I made a custom exhaust for my Z51 before I traded up. If I have to I’ll fab something up to make this work. However if end up with another 7k bill or something crazy like the last repair I may go back to stock and sell it. Really hoping they can resolve the torque tube problems.

 

You don't need to remove the rear panel to check if you have the springs on your Corsa valves. I went through the same thing as you with the Corsa system. Just lay on your back and get under the rear of the car, unbolt one of the NPP actuators and remove it. Then reach up and turn the vale by hand, you'll know right away if there is a spring in there or not, they have a lot of tension and will always hold the valve wide open. If it turns easily and doesn't go back to the open position then you have the original Corsa version without the spring like I had. Corsa replaced that for me with the new version and all has been great since.

 

Thank you, I will try that when I get the car back. I don’t think I could get to the bolts for the actuators but maybe I can. I doubt Corsa will replace them for me. I purchased these new in an unopened box but from a second party, so no receipt. If it’s the old style I’ll likely have to fab something up of if I can. I will check with them though. Thank you for your input and suggestion.

 

It's quite easy to reach the bolts unless you have hands that are triple the size of the average human.

 

Haha I got normal hands. I just can’t bend worth a damn after the knee surgery.

its gonna be a bit though before I get the car back. They took it apart changed the pilot bearing and it’s still making noise so it’s getting taken apart again. Probably at least week or more before I get it back.

ill update the post then. Hopefully I don’t report another huge bill.

 

Damn, I have the old version of the exhaust and I have a big bill coming my way for other repairs. Also just found out my sister has cancer, it’s been a crappy day.

 

Final update on this;

I did the NPP relearn twice and no change. The dealer was wrong about which version of the Corsa mufflers I have. As suggested above I got under the car and removed one actuator. I confirmed, the springs worked as intended and send pics of the valves to Corsa who confirmed I have version 3 of the mufflers. FYI, there is a conversion that can be done on the version 2 to update them, it's only 30 bucks but was not needed. If you have version 1 you can not convert them to version 3.

This could only mean that for some reason the actuator was holding the valved closed even though open position was commanded. This was only happening on the Corsa mufflers though and not the stock mufflers. That was why I didn't initially suspect that there could be anything wrong except with the valve itself.

The reason and fix;

The mild to wild switch is the problem. I removed that and then the valves worked as they should through the infotainment center. The springs in the stock mufflers are stronger than those in the Corsa. Somehow with the mild to wild installed it would apparently still send a partial voltage to the actuator motor when it shouldn't. Stock mufflers could over come this and still open but not the Corsa since the spring is not as strong. There is no contact number for the mild to wild guys so I sent and e-mail but no response.

My suggestion for anyone who has a Corsa exhaust and a mild to wild.....Remove the mild to wild if you have any issues with valves not opening all the way. I should also note that I have a buddy who has the Akrapovic system and his valves were also having issues, they would also only partially open and would do so very slowly. He replaced the mufflers and the new ones open now but still slow in comparison to stock functionality. I suspect he may have the same issue (he also has a mild to wild) but his mufflers have just enough tension to make them open. IDK how strong the springs are on the Borla or other brands but unless they are as strong as stock this could be a potential problem for those too and all aftermarket brands.

 

I don't see how the M2W would have any effect on the NPP motors strength to open or close the valves. I think the issue was more likely the way the M2W system works in conjunction with OEM mode controls. There has always been some weirdness there if you try to use both at the same time.

 

From what I understand, the NPP motors only close the valve they not open it. Once the voltage to the motor is turned off the spring alone opens it. I don't know the reason why with the mild to wild the motors were still applying partial voltage (educated guess). I was not trying to use both methods of controlling the valves, I used only the mild to wild for about a year and didn't use the OEM controls until after I remove the mild to wild.

I would agree this is a weird thing as are a lot of C7 corvette electrical issues but I know I'm not alone. Another forum member here experienced the same thing with his Corsa extreme exhaust and his mild to wild set up. He even tried getting a new mild to wild switch and still the problem persisted until he removed it. Unfortunately, I didn't take his experience to heart since the mild to wild did work on my stock mufflers and thought my situation was different. I should have taken the 30 seconds to test it rather then make the faulty assumption that I made.

I guess if really wanted to know what was going on I could hook the mild to wild back up and test this theory with a volt meter but I'm inclined to mess with it anymore. It all works now and I'm not too concerned about the loss of the mild to wild switch. I'm leave it open most of the time anyhow as the Corsa sounds awesome! Changing it in the OEM controls only takes a few seconds longer. I just figured it as worthwhile sharing my experience in trying to run the two products together.