Theta

Nope, no CELs reported!

vetehead

If you get either intune or trinity you won't be sorry.....

schitzo

Looking at the wiring diagram, it would appear a pulse width modulated (PWM) signal generator, which can be remotely controlled if desired, is all that is needed to control the rear most valves independent of the BCM. Shouldn't be too difficult to build a PWM generator.

xp800

Updated my OP as well.

For this past week, I have set Engine Sound Management back to Auto with fuse 41 removed in order to validate no CEL in this mode as well. Driving in Tour and Sport, no CEL. I was concerned that constant calls for the NPP to be closed in these modes (rather than just the 1700RPM hitch in ESM Off) may cause an issue. This is also important since any external switch would want to rely on ESM Auto as the base state which the switch would then override for 100% open NPP. So good news!

Theta

Great to hear - no issues here, either, with CEL.

Edit: On to something with the wireless again... Was thinking too complex when all it needs it the M2W with a different fuse and a slight tweak...

Oliver37

After believing that I was perhaps the only person who would ever notice the ~1700rpm valve closure even in Track mode, I was very relieved to find this thread. I have spent the last few months wondering if there was something wrong with my car and living in fear of having to describe what was going on to the dealership. Anyway I pulled fuse 41 this morning and it works as advertised! I never would have guessed that in a car this complicated it would be so easy to get the computer out of the way. Now if it were only this easy to get the throttle to close when you lift off the gas...

#1c6

where is the fuse box located that has the #41 fuse?

xp800

Right hand side of engine. Large, flat lid with two locking tabs on the front.

#1c6

thanks xp800! i should be getting my c7 next week and that will be my first mod. i pulled the fuse in my c6 npp and never looked back. loud pipes saves lives. lol

RonC7

I just picked up VIN 223xx on Thursday. It seems that Performance Exhaust OFF really means OFF. At idle in Touring mode after a 40 mile drive - OFF has valves in outer exhaust tips open, AUTO has valves closed. Am I missing something or has the software been changed from cars built earlier? M7, Z51, about 180 miles on the car if this matters.

Theta

Ron,

There are mixed reports here and there. It's really all about the tip-in. Some of us get really annoyed with it, others don't.

I've not seen any programming change come across the system for this, so I'm inclined to say that it's the same with yours as with the rest of ours.

Try it out for a while and see if you notice that 1700rpm tip-in. If it doesn't both you, no worries! If it does, fuse #41 removal is for you.

RonC7

Thanks Theta! The car is so new there are lots of settings to play with. From rereading this thread just because the valves are open at idle does not mean they are open all the time. You guys are saying the valves close in higher gears below 1700 rpm and then open quickly at 1700. I'll pay more attention in higher gears.

Thanks for sharing your technical knowledge with the rest of us. That's the neat thing about the Forum.

BMadden

OK, stupid newbie question time. Just got the car today and can't locate Fuse 41. Is there a pic anywhere that illustrates it?

Theta

Serious time crunch, so I borrowed a pic to edit from - sorry to that person, running out the door.

It's the 20A micro fuse (yellow).

BMadden

Thanks, Theta.

Baron7700

I read the first 3.5 pages of everything in here, and then just skipped ahead.

I have an M7 z51 NPP car. I have my engine sound management set to OFF. My valves are AWLAYS open without doing anything else.

At start up: Barks loud. Almost sounds cammed stock. Much louder than with it on.

Driving in any mode: its definitely open, even with it below 1700rpm. I can hear it burbling and popping (almost sounds like an aftermarket exhaust) when I roll, especially in and out of my driveway (1/5 mile long with about a 8-10% grade).

Eco Mode: I mostly drive in eco mode. I've seen people say that the NPP kicks on and off when going into 4 cyl mode. I dont believe it is the NPP turning on and making it quieter, as much as its just now only running 4 cylinders instead of 8. The sound will definately change and be quieter. I can tell you that I know my NPP valves are STILL open, because Ive gotten pretty good at feathering the throttle and staying in 4 cyl mode and accelerating a bit. I can def hear the 4 cyl exhaust note instead of quiet nothingness that it would if the valves were shut. Doesnt sound great. (For those of you who are curious, go into like 5th at 60mph where you are like 2k-2200 rpms and have it kick into 4 cyl mode with the npp open and slightly accelerate, you can hear the exhuast burble and it sounds weird).

My car is vin #00692. I believe I was the third person to take delivery on this forum on 9/24. Car was built on 9/11. I think something is wrong with your cars.

EDIT: When you say "tip-in" what are you referring to?

xp800

Baron,

I agree with most of your observations except a couple key ones.

As for something being wrong with our cars... I've owned two different C7s. VIN #983 and now #17666. Identical in EVERY way except VIN. Pertinent to this thread is that they behaved EXACTLY the same way with the behavior of Engine Sound Management (ESM) Off and the 1700 RPM hitch. So far all the others in this thread (A6 and M7) have reported the same results when they know what to key into -except- you.

In V4 mode, the valves that close are not the NPP valves. The V4 valves are the ones in front of the mufflers. The NPP are in the exhaust outlets. The ESM controls only the NPP valve behavior. I have noticed no difference in ESM Off and fuse 41 pulled when in V4 mode; this would imply NPP valves don't do anything in V4 mode.

For ESM Off: The 1700RPM tip-in I describe is most noticeable in daily driving when you upshift into 4th and 5th and the revs drop under 1700RPM. Then you 'tip-in' to accelerate, and it goes quiet until 1700RPM and then the NPP valves open and it's abruptly 'loud' again.

I agree there are times when the NPP valves are open below 1700RPM in other driving conditions (coast down/decel, highway steady state in 6th and 7th). It's really the tip-in during acceleration in 4-5 that it happens.

Try this experiment. ESM Off. In 4th gear, drive along at 1400RPM. Then roll into the accelerator quickly and listen as the tach swings past 1700RPM. Let us know what you find.

Theta

Respectfully, sir... your statement is incorrect. I'm glad the previous poster pointed this out, but this happens when you skip over several pages of information.

Also, I have #486... So, yeah... Not an issue with our cars.

Baron7700

Welp, keep on keeping on then. Interesting find to say the least. The little bit I drive mine on the street I've never really noticed, and its generally driving like a grandpa to the street and back.

I'm planning on getting headers and feel that having the "option" to open and close the valves is a plus. But in the meantime I guess this is way to make it "louder" while cruising along at low rpm. I never noticed.

I skipped over the last few pages because they contained posts that were duplicate once the originals were edited with updates. Sorry?

Theta

No worries - sorry that came off harsh (I re-read it afterwards)... It's just that it's been beaten back and forth by people that say it does or doesn't exist.

It's programmed in the CCM to have that tip-in delay even in race, and of course in sport.

There's no deviation in model or software that changes it - I promise you. Some people just notice it more than others.