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Loud Vibration at Idle

Discussion in 'E90/E91/E92/E93 (2006-2011)' started by fer98asg2, Jan 7, 2014.

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    fer98asg2

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    I recently raised my car (2007 E92xi) up using jacks and the stipulated jacking points for the front center and passenger front (side). I raised the car fairly high to install some carbon fiber bits and am now hearing a loud vibration sound in the cabin on idle. If I apply a small amount of throttle the sound goes away. I tried to take a video, but the sound was not audible in the video. It almost sounds like a buffering sound (as if you cracked a window in the car going down the highway). Does anyone have an idea of what this could be? I would appreicate any help someone may be able to offer.
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    charlson89

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    Really hard to say without hearing the noise is there any way you could get a video of the noise?
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    fer98asg2

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    I will try and capture it on video again, however I'm not sure it will be audible. When first starting the car it sounds fine, however once normal idle is achieved (around 600 RPM), you will hear a noticeable vibration sound.
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    charlson89

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    Can you tell the area it is coming from engine bay, under car, inside vehicle?
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    eblue540 Fourth Gen Bimmers

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    Sounds like something is resonating at a frequency which is excited at idle RPM. I would assume that you have gotten out of the car and listened all around the bottom of the car to see if you can zero in on it. If you do that wear some protective gloves and touch all the parts your touched or worked on when you did the mod and see if that stops the sound. You might need a helper in the cabin while you touch everything to sing out when you find the offending part.

    Good luck.
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    fer98asg2

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    I wish I could pinpoint it that easy. From the engine bay, you cannot hear exactly where it is coming from, and it is faint from the outside of the vehicle even with the hood up. I have not tried from under the car, will do so as soon as I get a chance. As far as parts I touched, that's just it, didn't touch any. Installed a front lip diffusor and side splitters on the rocker panels. Did not touch any engine or exhaust components, closest I came when jacking the car up from the center front jacking point. Appreciate your help on this guys.
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    eblue540 Fourth Gen Bimmers

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    What exactly do you mean by "center front jacking point"?
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    fer98asg2

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    steven s

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    I noticed our 03 Mini has a spot very similar.
    I had the left side on stands then decided to put the right side on stands to level it off.
    I didn't have room for a jack so I used the spot you used.
    I found the car very unstable or rather the jack very unstable.
    I lowered the car quickly and abandoned the idea.
    I'd be curious if that point is to be used with a special jack.
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    charlson89

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    That area is ok to use for jacking but like steve said it does make it unstable.
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    fer98asg2

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    Would jacking from this location in any way/shape/form cause my motor mounts to go bad, or perhaps be the straw that broke the camel's back if they were already going bad? Or jacking it very high from the front passenger jack mount? I'm going to replace the motor mounts this weekend praying that this solves the problem.
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    MGarrison

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    I don't know if E92 motor mounts are all that short-lived, but, maybe, might be worth a shot. Seems to me any number of things could have shifted, in or out. If the noise is always there and loud in the cabin, I'd start by eliminating interior possibilities. If it's loud in the cabin, I'd move around and try and identify where the sound is loudest. Be thorough - listen around inside & out with all doors closed, both open, either open, the trunk open by itself & in combination with the doors & sunroof, listen in & out with only the sunroof open, & so on, anything you can think of.

    One of these might be useful:

    http://www.harborfreight.com/mechanics-stethoscope-69913.html

    If you can find the area loudest in the interior, then I'd see if the corresponding area from outside the car seems to also be an area centering the noise, with a corresponding volume level. Then you'll have a better idea if it's something in the cabin, such as trim or panel pieces, or something else mechanical, or the underside, and so on. If it's loud and consistent, hopefully by listening around, you can narrow down the source area, and eventually isolate, identify, & eliminate. There are a lot of underbody trim panels, but it would seem a bit odd (to me, anyway) they would be the source of your noise and be louder on the inside than out.
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    fer98asg2

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    So I finally had an opportunity to get under the car this weekend. Removed all the plastic underpinning replaced the passenger side motor mount which was not bad (unable to easily get to the driver side due to the drive shaft on the AWD). Transmission mount looks fine. The vibration is coming from the engine which travels down the exhaust (which is not hitting anywhere). I cannot feel any vibration on the acutal car frame while underneath. Tried the stethescope to no avail. Once again, only noise comes from direct contact with the engine. Does anyone have any ideas? This is driving me crazy. I would love to post pics, but for some reason it is not loud enough to be piced up on audio. Once again, it is like having a window partially cracked when going down the highway and getting a buffering sound. I'm at wits end. Is there any way the engine coudl have shifted and is now hitting the firewall (eventhough we used legitimate jack points)? Perhaps a too low idle (600)?
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    MGarrison

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    Hate to have to suggest it, perhaps remove the bits you installed, then see if the noise is still there? That would theoretically eliminate whether that part of what you did is a cause of the noise. Such an odd issue you seem to have here - try googling, or searching the message boards on bimmerforums.com, bimmerfest.com, e90post.com, and ask there too, maybe you'll land on someone that's had something similar. Seems odd that it's so loud inside the cabin.
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    charlson89

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    Is the noise louder under the car or on the top side of the engine? Is it toward the front of the engine bay or back?
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    fer98asg2

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    You are unable to hear the noise except in the cabin. Having said that, it makes it difficult to locate. I did appear that when we applied pressure to the exhaust, the sound seemed to disappear; however, as mentioned before, the exhaust is not touching the body anywhere. The only place I was unable to view was next to the firewall, yet I'm unsure what could have caused a shift to make something hit the firewall.

    I can try and remove the pieces I installed, yet I honestly do not believe some bolt on spoilers on the front and sides of the rockers and front fascia would be the cause. They are not vibrating eventhough I still might do this.

    Thank you again to everyone for thier help.
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    MGarrison

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    The exhaust sounds like a lead on it, if moving that around eliminates the noise - I'd look at the exhaust manifolds and downpipes and see if something isn't touching the firewall or transmission/drivetrain tunnel, particularly up front near the engine, and any place that would be hard to see. Bright flashlights... inspection mirror...
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    fer98asg2

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    Need some help, as I mentioned above, I was able to change the passenger side motor mount. Does anyone on the forum have any experience replacing the driver's side motor mount on an XI. I have to say, it's turning out to be quite the challenge, I really don't want to remove an axle just to change a motor mount. Anyone have an idea on how to accomplish this, or how much we can raise an engine off the subframe before it becomes a problem (seals, driveshaft on xi, etc.)? Thank you.
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    charlson89

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    I normally lower the subframe slightly to get the motor mount out easier really there isn't that much room to move the engine up because of the trans tunnel but while lowering the subframe it's a lot easier.

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