[Xaxas]

Originally Posted by arpad_m

For example, mine closes the valves when cruising on the highway at 65-70 mph in 8th (top overdrive gear for the A8). Car is now louder with long tube headers and no secondary cats, which also magnifies the difference between closed and open, so it's pretty easy to tell.

Is it related to AFM? Only thing I can think of, but OP has a 1LE and I swear to god I notice no difference.

[Chutzpah]

Originally Posted by Xaxas

Is it related to AFM? Only thing I can think of, but OP has a 1LE and I swear to god I notice no difference.

In an auto with AFM, you’ll likely notice little to no difference with the fuse pulled at cruising RPM’s. Installation of a Range device (AFM bypass) module, then pull the fuse, you’ll get a nice V8 burble while cruising, including a slightly higher volume exhaust note at other low rpm speeds.

I disliked the fuse pull in the city without the range device as it created a pretty noticeable fart sound when the AFM valves opened, at low speeds.

[arpad_m]

Originally Posted by Xaxas

Is it related to AFM? Only thing I can think of, but OP has a 1LE and I swear to god I notice no difference.

Originally Posted by Chutzpah

In an auto with AFM, you’ll likely notice little to no difference with the fuse pulled at cruising RPM’s. Installation of a Range device (AFM bypass) module, then pull the fuse, you’ll get a nice V8 burble while cruising, including a slightly higher volume exhaust note at other low rpm speeds.

I disliked the fuse pull in the city without the range device as it created a pretty noticeable fart sound when the AFM valves opened, at low speeds.

AFM? What AFM?

Silly jokes aside, AFM nothwithstanding (it's turned off on my car anyway) the tune has threshold tables for opening and closing the valves for each gear, mode and rpm. Unless someone pulls the fuse or tunes these tables, the valves will close in high gears at low rpms, see below. This is what I was talking about.

[JamesNoBrakes]

Originally Posted by FarmerFran

See , please, please post some audio. I never got this out of mine.

Fair enough, the engine blew so maybe I am the outlier, but I think not.

TR6060 maybe?

The difference is at lower RPM range and partial throttle. Even in track "mode", the exhaust is "closed" a large amount of the time, can't remember if it's 1500 or 2000 or so that it "opens", but it's for sure closed below that. In other words, even in track mode, unless you are pushing it like on a track, it tends to be closed a lot of the time. Even with this pull, it's not "loud" here or at highway, it's just more consistent IMO. I race against some Mustangs that are insane loud, with either straight headers (no muffler) or exhaust that makes them the loudest (and not in a good way IMO) thing on the track, and everywhere else. I don't want to be the loudest, but I do think it sounds better and more consistent with the fuse pull.

[Xaxas]

Originally Posted by arpad_m

AFM? What AFM?

Silly jokes aside, AFM nothwithstanding (it's turned off on my car anyway) the tune has threshold tables for opening and closing the valves for each gear, mode and rpm. Unless someone pulls the fuse or tunes these tables, the valves will close in high gears at low rpms, see below. This is what I was talking about.

Thank you for providing the tables, if I'm understanding it correctly, the "Performance Mode and Action" table means it's closing the valves for short intervals in some modes? Threshold 3 in Mode 0 closes at 2900 and opens at 2950? Some go from 2000-2800 is this correct? If so, why would GM even do that? Not like I've even noticed but the only reason I could think of is unwanted frequencies/general sound tuning.

[zstanny]

First time hearing about this soft code from the NPP fuse pull. Did this only come up because of you getting this E-diff calibration? Would the soft code be logged during just a standard oil change service?

[PnCRedJwl2SS]

I've had the exhaust fuse (F51) pulled since the first week of ownership (Sep 2016). While it was still under warranty I never had a dealership say anything to me about it. I'm guessing they never even noticed it. If there's a code, it doesn't seem to affect warranty work.