07WhiteV6

Hi guys,New guy here, althoguh I lurk quite a bit. My 07's developing a problem that my dealer is convinced "not an issue"...but I'm not.

Here's the description and then I'll tell you what my dealer said.

At a constant speed, about 70 MPH, there's a "flutter" that you can hear. Like a low frequency harmonic reonating inside the car. It's to the point where it's such a low frequency you can kind of "feel" it.

Now, the dealer says "This is not an issue. It's simply the exhaust system and you've hit the 'resonance' of the muffler. Since the muffler is at the "end of the exhaust line", it's going to be more pronounced. Turn your radio up or change your speed."

When I challenged them on this saying "I'm certain Ford wouldn't allow this to be out on the market like this", they told me that they've changed the entire exhaust system on a customer's car just to have Ford "kick it back" saying there was nothing wrong with it.

Now, using your guys vast depth of wisdom and knowledge, can you tell me what this noise is that I'm experiencing? I've tried searching for it, but seem to come up empty...maybe I'm not using the right terms but I need your help.

For the record, it's an 07 V6 automatic and has just over 4500 miles on it.

tientran

If you feel a little vibration around 70 mph, it is normal. My Mustang car andthe Mustang that I rent have the same way. You can search with Vibration headline. Many persons discuss that issue.

99flhr

70 mph is approx 2100 rpm
try steady 2100 rpm in 3rd & 4th gear, flutter still there? (then perhaps yes it`s the exhaust "resonance")
try 70mph in 3rd & 4th gear, flutter still there? ( now it`s related to road speed and not engine rpm, exhaust theory less plausable)

07WhiteV6

I've experimented with it (turning the "O/D" on and off) and it seems to be RPM dependant.

Sooo, if this is indeed a natural occurance of the exhaust system's resonance, will I have problems when I switch to a true dual system? (I've got my eye on the Pypes set up...and have questions but will save those for another thread. One issue at a time. LOL!)

07cspony

I have a slight vibration at 70 mph or 2000 rpm in 5th gear, about 2500rpm in 4th gear. I have attributed the vibration to either a tire/rim issue on one on the front tires. I vibration does not exist at any speed other than 70 mph.

RED121572

Get anoff road H pipe.That will solve all of your harmonic problems.

tientran

I made my car to true dual exhausts with X pipe. The car less vibration at 70 mph a little bit, but the vibration is still there. I heard that the harmonic is due to driveshaft, not exhaust system.

07WhiteV6

I did that and I see a lot of discussion about driveshafts being out of balance. I'm not sure that's my issue...but I won't rule it out.

FrostByte

Put some LMII's on it!!!!

tientran

My car had driveshaft unbalanced. I vibrated at almost all speeds. The dealer replaced the driveshaft. After replacing the driveshaft, the car still vibrates, but only at 70mph.