Vibration from stop at light to medium acceleration
 

I have a 2006 Ford Five Hundred Limited that is experiencing a vibration problem.
The vibration occurs consistently from a stop, but not at speed, when under light to medium acceleration. The vibration sounds like it is coming somewhere in the front end and is not associated with alignment. The vibration only happens in a specific band of acceleration that represents perhaps 20% of the range, if 1/10 is barely accelerating and 10/10 is full throttle. The vibration stops once the car has reached about 25 mph.
Can anyone shed some light on where to start looking?

I have taken it to two dealerships with no results so far, although that is a long story in itself. The next step is going to be to teach my wife how to reproduce the problem and have her take it to a different dealership near where she works. Any insight would be helpful though.

Thanks!

RE: Vibration from stop at light to medium acceleration
 

I have the exact same problem with my '06. I took it to my dealer and he found a tsb with similar symptoms calling for some spring gadget in the exhaust area, but unfortunately it didn't fix the problem. However, I did see some info (epinions.com)about an engine vibration balancing bar out of adjustment on an '05. I'm going next week to the dealer to see if that's a possibility, yet I would think something that descriptive would be the first thing they would check. Wish us luck! I'll post result.

I'm going to bump this back into view hopng to get a solution, I'm have a similar problem with my 2007 Ford 500 , terrible engine vibration/noise only in the 1200 to 1400 rpm range, I can drive thru it, if I power brake in drive, I can get it to happen every time, doesn't do it in reverse.

Any help.........pleeese !!

I'm just fishing here, but were the motor mounts checked out?

Yes, motor mounts are good, it seems to be a harmonic type of vibration/noise, I have looked at everything very carefully with no solution, occurs in that very narrow rpm range and it's very noticable.

Can you duplicate the vibration with the vehicle in neutral? Is it possible when the engine is in high torque range the exhaust system is touching something and causing it to echo throughout the car?

No, in Neutral it's smooooth, in reverse it's okay, only in drive under load at the 1200 - 1400 rpm range in gear under load.

I did try to reposition the exhaust by loosing the flanges and wiggling the exhaust to a slightly different position then tighten, seemed like it made a difference for about 3 or 4 pull outs from a stop and then back to it's old ways.

It would seem you are in the right area. Can you trace the exhaust system and see anywhere that the piping may have made a shiny spot or is too close to something?
That something could be anything because the piping is usually free to move every time the engine moves on a pull out. That's why I questioned the motor mount(s).

I had someone power brake the car at the rpm range while I was keeping my foot on the tail pipes, I could feel the heavy vibration but applying pressure did not stop it, the exhaust is not hitting anywhere, that is why this problem is so strange.

I have heard of alternators vibrating at certain RPMs and required additional supports to effect a cure, but I couldn't say for sure that this could be a possibility with your vehicle.
I am puzzled as to why the vibes disappeared temporarily when you repositioned the exhaust system and then came back. Can you get a better sense of the location by looking under the hood for something hitting anything when you can create this vibration?