[ReFLeX135]

I took my car in for some transmission issues and I was told that GM Engineering said that it was completely normal and by design for my A8 SS to make grinding noises due to light acceleration. I was told "three cars the dealership did the same noises."

"This concern is caused by the normal function of the active fuel management system. Was duplicated. This is typical active fuel management characteristics and all like vehicles do it."

1. Does AFM disable ever when in manual mode? I read it might somewhere...
2. If I can reproduce this in V8 mode only would it suggest it isn't AFM?
3. I read I can disable AFM with a fuse pull, but it will throw codes. Is that OK to attempt and not void the warranty? Will I have to have the codes cleared or something?

It would be helpful to know if any of your SS A8 cars make a grinding noise coming from the front, at low speeds with slight throttle. Is anyone willing/able to post a video of what it sounds like to drive your car at low speeds and slight acceleration? I would really appreciate it.

Steps/Settings I've noticed it in:
1. Cold or Warm
2. Sport Mode (don't think it matters)
3. Leave it in auto (skip below to use manual mode)
4. Go 20-25MPH
5. Coast shortly to let the RPM go down to about 1.2k (not always necessary)
6. Apply small amount of throttle to accelerate by 1-2 MPH.

Or same situation but lock it in gear:
3. Engage manual mode and leave it in 2nd, 3rd, or 4th
4. 20-40 MPH,
5. Maintain or coast
6. Apply small amount of throttle to accelerate by 1-2 MPH.

After that small throttle I hear grinding, and can repeat it consistently, every time.

I told the dealership I wanted them to demonstrate my noises in their cars but they backed out of the appointment the day before =(

Thank you!

Grinding whole video: https://youtu.be/h4p1PECUcC4
Grinding at 1:12 to finish: https://youtu.be/g6fK3B8DEEg?t=73

[Razzaa]

Originally Posted by ReFLeX135

I took my car in for some transmission issues and I was told that GM Engineering said that it was completely normal and by design for my A8 SS to make grinding noises due to light acceleration. I was told "three cars the dealership did the same noises."

"This concern is caused by the normal function of the active fuel management system. Was duplicated. This is typical active fuel management characteristics and all like vehicles do it."

1. Does AFM disable ever when in manual mode? I read it might somewhere...
2. If I can reproduce this in V8 mode only would it suggest it isn't AFM?
3. I read I can disable AFM with a fuse pull, but it will throw codes. Is that OK to attempt and not void the warranty? Will I have to have the codes cleared or something?

It would be helpful to know if any of your SS A8 cars make a grinding noise coming from the front, at low speeds with slight throttle. Is anyone willing/able to post a video of what it sounds like to drive your car at low speeds and slight acceleration? I would really appreciate it.

Steps/Settings I've noticed it in:
1. Cold or Warm
2. Sport Mode (don't think it matters)
3. Leave it in auto (skip below to use manual mode)
4. Go 20-25MPH
5. Coast shortly to let the RPM go down to about 1.2k (not always necessary)
6. Apply small amount of throttle to accelerate by 1-2 MPH.

Or same situation but lock it in gear:
3. Engage manual mode and leave it in 2nd, 3rd, or 4th
4. 20-40 MPH,
5. Maintain or coast
6. Apply small amount of throttle to accelerate by 1-2 MPH.

After that small throttle I hear grinding, and can repeat it consistently, every time.

I told the dealership I wanted them to demonstrate my noises in their cars but they backed out of the appointment the day before =(

Thank you!

Grinding whole video: https://youtu.be/h4p1PECUcC4
Grinding at 1:12 to finish: https://youtu.be/g6fK3B8DEEg?t=73

Mine doesn't do any of that.....

[Johnwon]

Mine does not make that noise either.

[GP86]

I've never heard this on mine.

Can you set your instrument cluster to show the fuel economy where it will indicate V8 or V4? What does it show when this noise is being made?

[ReFLeX135]

Thanks for chiming in guys!

Originally Posted by GP86

I've never heard this on mine.

Can you set your instrument cluster to show the fuel economy where it will indicate V8 or V4? What does it show when this noise is being made?

I'll go check right now!

[ReFLeX135]

Here's a good long video with the V8/V4 mode display visible and the grinding consistently occurring using various ways. It occurs while it stays in V8 mode.

[Razzaa]

Originally Posted by ReFLeX135

Here's a good long video with the V8/V4 mode display visible and the grinding consistently occurring using various ways. It occurs while it stays in V8 mode.

That is weird!! I would drive the snot out of it until it breaks!!!


Off topic: How do I get that display configuration for fuel and temps?

[BigCee66]

Man I'd go back and ask that these so called GM Engineers put this in writing about these sounds being normal. Sounds like some typical dealer lies.

[SSSHYBOY]

AND go for a drive with another car on the dealer's lot and ask them why THIS ONE doesn't grind.

[quikag]

I hear a diesel type light clatter at very light throttle but have always attributed it to being in V4 mode. Guess that's not the sound you are heading.

[Wolvie70]

Just checked this on the way into work. No grinding noise. The only thing I hear is a little noise when it is switching from 4 -> 8 cyl. I would not call that noise a grind.

[HCGxKaLiBeR]

Mine only does that when revving while stopped. (Park or Neutral)

I can hear the grind when I suddenly hit the gas pedal.

[jimmypop13]

I can't tell what you are referring to from the video. Definitely not afm valves as the worst they could do is squeak upon opening or closing. And that only happens during the transition and is very quick. Get far away from that dealership and find a better one asap

[Joey Rosario]

Sorry I can't help with my 2SS A8. I have never drove it with light throttle