I have a 07 M6 with 18k on her; MODS are verraram snake charmer CAI with throttle body extender, NPP Z06 mufflers w/NPP, DIABLO 91 octane performance tune. Ok here is what she is doing and what I am hearing; when she is at idle all is good then I rev her up to about 2200-2500 RPM and right at 1900’ish there is a strange sound that I can only explain as a low pitch grinding sound or kind of like when you coil a spring in a closed container too much and it gets sprung on you. It lasts only a nano second but it is evident. I noticed it while driving at low to mid speeds when I shift 2nd through 4th I rev her up push the clutch in and shift right at the 1900 mark I can hear the sound in the car,( only because I am listening for it), and feel a little vibration in the shifter. I get the vibration in the garage when the car is in neutral and the clutch is not engaged also. It occurs a lot but not every shift.
I have taken it to the dealer and of course the car didn’t do it then, and they said it sounded normal to them, after 2 ½ years of driving the car I know what it normal sounds like and there is a new strange sound and vibration in the gear shifter.
Any suggestions or tips to get me pointed in the right direction? Of course the factory warranty expires in Feb. Thank you in advance for your thoughts.
CHIEF

 

The same thing has just recently happen to me... It just started within the past few days after a trip to orange beach/panama... It only happens when the AC is on and it comes and goes... I'm taking it to my dealer Monday, I will let you know what they find.


SS

 

Thanks I just checked it in the garage and indeed it only happens when the A/C is on. It looks like it is pointing to the compressor.
I love this site, now I can go point those pukes at the dealership in a direction.

 

I was going to suggest the compressor. Mine started doing the same thing about a month ago. It turns out that the refrigerant charge was down to 0.6 lbs (system capacity is only 1.1 lbs). Interestingly, it still blew cold air.

 

I was going to suggest buying a DIGITAL recorder, not a tape recorder because tape hiss will hide noise, for about $33 a "RCA Digital Voice" (RP5022) from Walmart. The bar code is: 0 4431965125 6, this recorder works great and I used it at Bowling Green Assy Plant to let Corvette Engineers listen to a problem I had with my C6.

 

First I dropped her off two weeks ago because I could hear a sound coming from the engine when I rev her up, but they could not hear anything and gave her back to me that day saying they could not find anything wrong.
Ok so I dropped her off on Wednesday morning and Wednesday evening they said she was ready to pick up. The mechanic said he looked at it and found two lines coming from the compressor were rubbing so he separated them and he noticed the grinding stopped…….
So I said wow two lines touching would cause the grinding sound from the motor and a vibration I could feel in the shifting ****? And of course they said well you know a vibration can be felt throughout the car. A couple miles down the road I noticed the fan was on but the ac was not so I hit the auto climate control button and low and behold at 1900 rpms the grinding was there. So I turned around and went to the service manager and said guess what it is still there, THE A/C HAS TO BE ON FOR THE SOUND!! Thursday no phone calls or status, Friday afternoon, he called me and said hey Jim we are going to replace the compressor no-one has one in stock we will get one Monday and install it then.
Really, Really it took you three days to come to the conclusion I told you the first day I dropped it off. I understand that they get all kinds coming into their shop and all but come on the noise only happens when the A/C is on, and I told them the forums said it was the compressor.
Well that’s my story so far, hope it helps anyone with a grinding sound with the A/C on @1900RPMs.

 

As if its not enough that they have no clue they have to tak down to you like you have no clue. When dealerships try that wth me its hard for me to not lose it. Ignorance is unnacceptable when dealing with a 40k+ item.