AFM on the M6 ZL1
 

I have a 2018 ZL1 with the 6 speed manual, I'm reading that on the manual cars there is no AFM ( active fuel management ) system. However, even after the NPP exhaust fuse pulled at idle the damn car still gets quite. I know with the AFM there are another set of exhaust butterfly valves right after the back axle. They are there to provide back pressure when the AFM goes into 4 cylinder mode correct? So if the manual cars don't have AFM why does my damn car go quite at idle?
I want that obnoxious sound it gives at start-up to stay there.
So if the valves are in fact there and are in use, is there a trick to get those to stay open ( no tune )?
Thanks

no 6th gen ZL1 has AFM. The valves right after the back axle are the normal NPP valves.

furthermore the reason it goes quiet at idle is because on initial startup the RPMS are higher than idle speed, and as it begins to warm up the idle calms down.

shorthand if you want more noise, change the exhaust or add headers.

Interesting, yeah the more i read through i see where this was up for debate. I see where some have proved it is not on any ZL1. It's cold out now i went and tried to capture what i was hearing, I see what your saying about the RPM's are higher at start up, this is obvious. However what im hearing is a distinct sound of the exhaust getting muffled as if the NPP valves just closed. usually on a warm day it happens maybe 10 seconds after start-up.

Thanks for the AFM update though.

It is also my understanding the timing is retarded at start-up to give it some rasp and aggressive sound. The timing comes back after a little bit of time, which might be what you're hearing.

did you pull the correct fuse? I’m guessing so, just might double check. i couldn’t handle leaving my stainless works NPP catback in track mode just to hear it quiet down at certain RPMS. I could not believe it wouldn’t simply leave the valves open...so i have a catback i paid extra to get the valves, but don’t use them lol.

SW Exhaust
 

Jvandy how are you liking the stainless works exhaust? Is it worth the upgrade over the stock suitcase?

I still like the sound, but am considering adding headers. It is THAT non-obnoxious lol. There is a drone zone at a certain RPM that you can easily avoid, this also does not bother me...just thought I’d mention it as it seems to be at the forefront of exhaust concerns.

I wanted the option to not piss off my neighbors, and loved stainless works stuff on my 16 GT. Borla was meh and not many other NPP options. That said, i don’t use it...even track mode would quiet it down at certain lower RPMs and i just couldn’t believe it. My fuse is still in my console and the car sounds great.

I have a couple clips posted somewhere, but if you’re wanting anything specific, just let me know and when the weather cooperates I’ll fire up the GoPro.

this is correct. while my zl1 (with borla exhaust) is loud on a cold start, my m4 (with awe exhaust) can literally wake the dead. and the m4 stays retarded, and therefore louder, for longer.

the reason the timing is retarded on cold start is to allow hotter exhaust gases out into the exhaust to warm up the cats, which work better at higher temps, to minimize emissions. there's no mechanical reason for the timing adjustment, and a lot of tunes actually take that out of the startup sequence.