bjones7131

I have a post out there on the "warble" sound the car makes when going in the 4/8 or 8/4 mode and a suggestion was to pull fuse 32 under the hood to see if that stopped the noise I am speaking of. That fuse controls the two adaptive valves that I am told is what makes the warble sound when lightly accelerating. Question: has anyone actually pulled the fuse and did it eliminate the noise I am speaking of and will it harm the engine if pulled. I am told the valves fail open if the fuse it pulled so it should allow exhaust to flow straight to muffler without restriction. I am also told that it makes the car sound awful. Thanks for any feedback U have.

Boiler_81

There are several threads on this. The bottom line is pulling the fuse will set a code and turn on the check engine light.

rogergcam

on our 2015 Z-51 I have pulled the fuse many times. I love the sound, but after a month or so I couldn't take the noise, and put it back in. It great for around town, but not on the highway. I did not get a CEL light...

05XLRtoC7_San Diego

Just pull fuse #42. Leave #32 alone.

MIGHTYM0USE

i have had my car since january and have seen it go into v4 once. the only indicator is inside of the mpg screens yes?

bob guzzy

If you pull both fuses you will set a code, but once you replace them and drive the car a few times the light will go out.

You can pull fuse 42 with no issues, what you get it is the sound of a corvette like it suppose to be.

robert miller

If you look in the chev book you have in the car. You can go in and set it from your S/WHEEL where it stays in sport mode all the time.

You don't have to pull nothing but then again will have to do the same thing again to get it to work back like it does now.

MIGHTYM0USE

are you saying that sport mode defeats all v4 operation? because that is different than everything else i have read so far. what about track mode? I never see mine on in eco mode so what is up with that?

eboggs_jkvl

My A6..

Manual Paddle no V4
Sport Mode v4/v8


Elmer

Glen e

Defeats :

On a8, using manual Mode/ paddles defeats, nothing else
On m7, only works in Eco ....

This is gospel......

Zymurgy

From his other thread, the OP is wanting to disable the AFM valves. Fuse 42 is the NPP valves. Fuse 32 is for the AFM valves.

Boiler_81

There is some confusion in this thread. There are potentially two sets of valves on C7s. There is a set prior to the mufflers known as the AFM valves. These are on all cars and are controlled by the ECM and open and close based on if the car is in V4 or V8 mode. These are the valves the OP was asking about. Pulling the fuse which controls them will set a code.

The second set of valves are located downstream of the mufflers and is only on the NPP equipped cars. Pulling the fuse which controls these valves will leave them open at all times and will not set a code.

Pulling the NPP fuse will not help the OP's issue. He needs to keep the car from going into V4 mode. As Glen E posted, the only way to do this in a stock automatic is to run the car in manual mode. You could put a tune on it to eliminate the V4 mode. However, doing so will invalidate the power train warranty.

There is a device which plugs into the OBD II port which will keep the car from going into V4. Search for "Range AFM Disabler". There have been reports the device must be unplugged if the car is going to sit for more than a few days as it has a significant key off load. I don't have any experience with it as I have a manual transmission car.

The first post in this thread has everything you need to know concerning BOTH sets of valves. https://www.corvetteforum.com/forums...ck-result.html

Zymurgy

Since he wants to see if the AFM valves are the cause of the noise he is hearing, he can either run with the tranny in manual mode or pull fuse 32. The Check Engine Light will go away after the fuse is re-installed and some driving. Either way, he can determine if this is the source of the noise and can then decide if he wants to get a Range AFM Disabler.

OP, pulling fuse 32 will not "harm the engine". Since you are so concerned about this, just drive around for a while with the transmission in manual mode so AFM does not activate. That will answer your "is this the source of the noise" question.

Boiler_81

I didn't see the other thread until now. I agree pulling the fuse for diagnostics will do no harm. The AFM valves are only there to tune the exhaust sound. The exhaust will just sound bad when in V4 mode with the AFM valves open.

bjones7131

If i drive around in manual mode i will have to use paddles to up and downshift and in this mode the AMF valves are in the open position all the time, correct.

bjones7131

Thanks for the replies, i think i will try driving in the manual mode and see if the noise isn't present.

Boiler_81

Correct

jimmyb

Sorry to cloud this further....(I have a manual)

I thought putting the car in "Track" mode would also disable AFM. Is this incorrect?

Jmmy

bjones7131

Not sure but i drove a short distance with car in M mode that others said would disable AFM and it may have but i still had the warble sound i am trying to chase down so i feel like i am back to square one. Curious r u experiencing the noise that my car is making? Thanks

Rooster OG

With a manual, the only way it goes into Eco mode is if you select it as a drive mode. So sport, track and touring = no Eco mode with a manual.