Last March I installed the Borla Atak on my C7 with NPP. Borla has an outstanding reputation and this isn't about knocking them. After a month I started hearing squeaking noises when changing modes or coasting at lower speeds. I tried GM Dri-Slide which worked for a day or so, then it would return. My local GM service tech said he felt it was likely condensation causing corrosion. I contacted Borla and they sent me a brand new set no questions asked in June. For a month, everything was perfect, then it started again. I finally gave up. Fortunately, buying from a reputable supplier, Zip, they were returnable for 1 year. I contacted them and they put me in touch with Borla for a return.
As luck would have it, 2 days before I went to reinstall the factory set, I get a check engine light. My son, who is a dealer mechanic, and did the installs brought over the code reader and sure enough, exhaust valve failure. He reset it and we hoped a reinstall of the factory exhaust would fix the problem. Instead, I immediately started hearing a loud clank clank when front valve should be adjusting. $400 later for a new valve, I'm now hearing the same sound, only much less volume and very infrequent, from the right side. I can't figure out if the Borla caused the valve problem or there's something up with the NPP system? I bought my own valve as I felt it was dishonest to take it to the dealer after putting aftermarket parts on, but with the second valve acting up, I'm wondering about the valves?
You cannot install these incorrectly or they won't screw into place.
Any thoughts would be appreciated.

 

What was the exact code?

Tim

 

 

That is not NPP related. That is related to the AFM valves (front most set of valves). The NPP valves to not supply a feedback signal to the CCM.

I developed plug in modules that will allow you to ditch the AFM valves altogether if you wish to do so. No CELs and AFM will still operate.

https://www.corvetteforum.com/forums...te-module.html

Contact Edgyvette if you would like to purchase a set. Revision 01 is the version you would need.

Tim

 

I'll look into that. Yes it was motor for the AFM driver valve. Now the other is acting up a tiny bit. I'm asking if there's a known issue with the AFM valves?
i assume the exhaust valves are closing because of going into 4 cylinder mode. I don't understand the system well enough to know if that has an impact on performance or fuel economy.

 

Do you do any long duration racing? Normal street driving should not cause issues but long stints under high load are known to damage (overheat) the actuators. GM chose NOT to re-design them to be more robust.

Are the actual valve assemblies factory or Borla? I'm sending a set of modules to Dave at Borla tomorrow for them to test out. The AFM valves have been a big PITA for many of the exhaust manufacturers and some users.

Tim

 

No, I don't do any racing. I've taken the car to 110-120 a few times but usually less than 30 seconds. In the old motor, it was obvious that the gear stripped as you can freely turn the piece that fits into the valve. I applaud Borla for attempting this, but my thought was in their design the valve was sloppy in the pipe compared to the factory. The replacement valve looks slightly different and the supplier seems to have changed by the tag on it, so maybe they have had issues from a previous supplier?
Again Borla is known as top end in most equipment.