"Rumble on Coast/Deceleration"

[SGT-MS6]

Howdy all, wasn't quite sure where to put this and after much searching did not see this. I haven't owned a car with a turbo before, so maybe it is normal, or it is due to the AWD, but not sure so throwing it out.

In my new '07 MS6, when I am in 6th gear mostly but also noticing in 4th and 5th, if I let off the gas sometimes and coast and then decelerate for a while without any breaking sometimes (and it sounds like from rear) I hear a "rumble" and "feel" some vibration. Not quite sure exactly how to describe it but similar to the sound when you are slowing down over those narrow, shallow speed strips in the road, but not as severe. This is not a constant thing, but one I notice from time to time.

Oh, I suppose it is important to note, my MS6 has just over 1900 miles on it and other than this has been flawless and I am very pleased. Thoughts, Help?

-SGT

 

[Igve2shtz]

If you are in 6th gear (or any of the taller gears) and you are decelerating, it is because the engine is trying to stall because the gear is too tall. The same thing happens to me (if it is what I think it is) around 35 mph I think in 6th gear, a little less in all other gears. Just put it into neutral, or downshift to second once you start feeling it.

 

[SGT-MS6]

That could indeed be it, as it usually is when I am 5th or 6th, but not as low as 35, could be around 40mph in 5th or 50mph in 6th. Perhaps this is really low for these gears, but it seems like on a flat driving surface with no heavy pull that this shouldn't be an issue.

Hmmmmm......

 

[Karma_hunden]

have it check, better safe than sorry. I think 40mph is alright for 5th. 52-53mph is right for 6th.

 

[Klip]

Try putting it in neutral when you decelerate, see if the rumble goes away. I believe what you are experiencing is the exhaust system resonating thru the car. It is much more pronounced with an after market exhaust such as CP-E's TBE. At least it is in mine, I put it in neutral and it goes away.

 

[SGT-MS6]

Thanks for all of the input. I took my MS6 in last night for some little touch up paint they owe'd me and the driver seat started to "creak" when I accelerated as my weight went into it. Plus the problem noted above and an "axle hum" that I have noticed when cruising under power. When I lift my foot off the throttle, it goes away.

I spoke to my long-term Mazda service lady (who is fantastic) and told her what was going on. So to date when they called me already this morning:

1) Ordered a new seat frame to replace the driver's side seat frame
a) I thought it was just loose or needed some grease, I suppose I was optimistic.
2) Paint work being done
3/4) My tech believes something is wrong and agrees it should not be making the sounds it is making and they got more details on how to reproduce as both are intermittent. Knowing my tech...they'll find it.

Wish me luck!

BTW, I don't have anything after market yet, I just ticked over 2K on the odometer...some mods will be coming...once the old wallet has some additional cash.

 

[pycmsp]

i am having the same problem going to the dealer is sounds like its the transfer case making the noise. i have an 06

 

[SGT-MS6]

Any word on your MS6? Both Speed "Qualified" Techs are saying both sounds normal. Hmmmmmm.......