StrayDog

Will pulling Fuse on C8 , allow NPP exhaust to stay open ? On learning curve with my C8

MagicGlass

Be they first to try it and find out!

Ragtop 99

Does the MyMode allow the exhaust to be in track mode all the time?

Pinmaniac

Yes, that is one of the options.

TJay74

Even with it being in "Track" mode if it follows the previous GM logic on the NPP modes it will still close while in Track mode once the car is under part throttle steady state cruising.

the_sim

There is a fuse that can be pulled but it is a double fuse. It has a common ground on the middle and power on the outsides. If you pull the NPP fuse it will also disconnect another circuit. Some people have said that they did not notice the flaps closing on their c8 while in track mode. I'll have to experiment myself once my car gets in.

StrayDog

keep me aware of your experiments ........... the C8 "gizmos" confuse my 71 year old brain.., Semper Fi

f360m

Had a tech pull the Micro3 fuse 20/21 and cut the leg off the fuse 21 position. Re-inserted that fuse which essentially opens the circuit to the exhaust valve solenoid, but keeps the circuit continuity that uses fuse 20. This does indeed keep the exhaust bypass valves open at all times ... however ... it also throws a check engine light. Put a new Micro3 fuse back in and all is right with world once again.

It appears that a Mild to Wild controller is not going to work on the C8 unless you don't care about the check engine light.

Bill Dearborn

C8 OM indicates AFM is disabled in Track Mode. That means the exhaust valves don't switch when that Drive Mode is selected. M7 C7s didn't quiet the exhaust when in Track Mode. The exhaust was loud throughout the rpm range and under light throttle conditions at 1500 rpms although at light throttle and 1500 rpm there wasn't much noise being made by the engine (no less than warmed up idle noise level).

Bill

TJay74

That is different than what other C7 owners and the 6th gen Camaro owners have seen with the factory NPP exhaust. It has been seen and proven several times, even in track mode once the car is at cruise speed and under steady state driving on the highway as an example the valves will close even while in Track mode.

Modshack

Chevy Dude says it was the Rear view mirror cam...
He's got a video showing fuse location and results..

Bill Dearborn

GM decided the exhaust sound was objectionable when the C7s AFM switched the engine to 4 cylinder operation. That is why the Stingray versions had two sets of exhaust valves (one ahead of the muffler and one after the muffler). Whenever, the engines switched to 4 cylinder operation the valves on the mufflers closed. If you were driving an M7 the C7 was only able to operate in AFM mode if the Drive Mode was placed in ECO. The people who said the mufflers closed during normal operation were driving A8s which needed AFM operational all the time to increase fuel mileage in order to reduce the gas guzzler tax. The only time you could prevent the exhaust valves from closing on an A8 was to place the transmission in manual mode.

I have been driving an M7 for 4 years and know what the exhaust does when driving in Track Mode as I have mine set in Track Mode all the time. The only time the exhaust gets quiet is when I put the Drive Mode into Eco Mode and the engine switches to 4 cylinder operation. As soon as it switches back to 8 cylinder mode the exhaust gets loud again. That is how I know when the engine changes operation. While I am driving at a steady cruise I can turn the Drive Mode dial from ECO to TOUR and back and hear how the exhaust operates. In TOUR mode it is loud all the time even when in cruise control in 7th gear at 70 mph where the rpms are below 1500. If I switch to ECO and if the engine switches to 4 cylinder mode I hear the exhaust get quieter and then as soon as it switches to 8 cylinder operation it gets louder. Now loud is relative since at extremely light throttle operation and just above idle rpm levels the exhaust sounds aren't very loud even with a straight through exhaust. You can tell that by just standing behind an idling C7 with the exhaust valves open.

I haven't heard of the C8 with DCT being listed as a gas guzzler so GM probably decided not to activate AFM in Track Mode and the fact they say in the OM that AFM isn't activated in Track Mode is a sure indication the exhaust doesn't get quiet in Track Mode. The only reason they quieted it on the C7 was to eliminate the objectionable 4 cylinder exhaust sound.

Bill

CP

Is there no objectionable noise when the C8 goes into 4 cyl mode? And how did they get rid of the vibration in 4 cyl mode like they did in the C7 dicking around with the torque converter?

NTMD8R

Pulling a fuse is essentially the same as disconnecting the electical connectors from the NPP valves.
That's what I am going to do.

JerryU

Yep folks who installed Mild2Wild (which is essentially 'pulling the fuse' with a remote relay properly wired) validated that even Track Mode (where I had my C7 NPP set) had the valves closed up to about 1700 rpm.) So cruising on the highway at 70 mph and flip to Wild (fuse back in the circuit) and sound increase. Some reported (as I experienced in my C6 where I installed a toggle switch connected to "pull the fuse" with a flip) there was a noticeable/objectionable drone at ~60 to ~70 rpm!

Have followed attempts to use Mild2Wild in the C8 (which didn't work) as well as someone who wired the "double fuse" were the NPP is one side. It did not work. So far have not seen a way to "pull the fuse."

hcvone

My 19' ZR1's in track mode exhaust was always open, my Z06's it was suppose to be open in track mode all the time, I am not sure it was all the time open

dmraco2021

So the valved still close in track mode in the C8?