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vibration at idle 99 a4

This is a discussion on vibration at idle 99 a4 within the General Help forums, part of the LSx Technical Help Section category; i recently have been having a vibration at idle. the stock exhaust was changed to a lm2. i have checked ...

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    Junior Member jefff82's Avatar
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    vibration at idle 99 a4

    i recently have been having a vibration at idle. the stock exhaust was changed to a lm2. i have checked it a couple of times and don't see it rubbing on anything. i did notice that the rear exhaust mount seemed a little bit wore out. don't know if this would help or not. the vibration only happens sometimes at a stop and vibrates the car not too much but enough that i don't like it. car has 128k on it. 99 formula a4 slp lm2. i know over the axle is a tight fit but would that cause vibration or a tap

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    Spaz is My Mentor SMWS6TA's Avatar
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    It wouldn't hurt to swap out the exhaust mount. Hell it's 15 yrs old. You may have closed the clearance gap between the body and the exhaust and that is why the rub.

    I doubt it but also check the engine mounts. They could also be getting worn out.


    Does the vibration make any sounds like tin or deeper sound?


    Also check the heat shielding around the exhaust. The shop might have knocked it loose. I know it took me a while to track it down but one of the screws was loose and caused it to vibrate.

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    Junior Member jefff82's Avatar
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    Quote Originally Posted by SMWS6TA View Post
    It wouldn't hurt to swap out the exhaust mount. Hell it's 15 yrs old. You may have closed the clearance gap between the body and the exhaust and that is why the rub.

    I doubt it but also check the engine mounts. They could also be getting worn out.


    Does the vibration make any sounds like tin or deeper sound?


    Also check the heat shielding around the exhaust. The shop might have knocked it loose. I know it took me a while to track it down but one of the screws was loose and caused it to vibrate.
    no real sounds to vibration just the vibration. i turned radio off and had windows down and didn't hear anything. i tried to find the pass rear hanger but couldn't find anything. just the drivers side. i just went out and looked at the exhaust again and noticed the y pipe had some marks on it where it goes over the sub frame connector where it looks like it has been rubbing. i lifted up the pipe a lil and shoved some steel wool to see if that was it. i guess ill find out in a couple days or so when i have some days off. the only other spot that seems close is over the rear axle area but looked like it had a gap

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    I would check the engine and transmission mounts for starters.

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    Junior Member jefff82's Avatar
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    Quote Originally Posted by pajeff02 View Post
    I would check the engine and transmission mounts for starters.
    I understand that itjust didn't do it until the I put the lm2 on. I just wondered if trying to get the stock pipes off may have done something to loosen up y pipe or exhaust. I figured the y shouldn't be touching the sub frame connector. would engine/tranny mounts cause that

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    Any idea the location, for instance when mine was vibrating it was right under my but and shifter when I would go above 2.5k rpms, ended up being a collapsed engine mount.

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    Junior Member jefff82's Avatar
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    Quote Originally Posted by florida4thgen View Post
    Any idea the location, for instance when mine was vibrating it was right under my but and shifter when I would go above 2.5k rpms, ended up being a collapsed engine mount.
    it only does it at idle. as soon as I touch the gas it goes away. doesn't shake at any other rpm. pretty smooth on highway and driving around town. it does feel under the seat that's why I checked the y pipe and saw some markings where it goes over the sfc. . it didn't happen with the stock pipe and magnaflow just when I changed to the lm2. I also tightened down the clamps again on the lm2 yesterday had become a lil loose I guess from the heating and cooling. hopefully that helps. the only spot I saw that was rubbing anywhere was the y pipe.

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    Understood. I guess it could be a contact issue then - something may have moved around after you started driving the car following the installation. The mounts are just common failures, especially as the youngest of our beloved cars is now at least 12 years old.

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    Quote Originally Posted by pajeff02 View Post
    Understood. I guess it could be a contact issue then - something may have moved around after you started driving the car following the installation. The mounts are just common failures, especially as the youngest of our beloved cars is now at least 12 years old.
    How difficult is it to replace the mounts as mine is coming up on 15

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    Transmission mount is a snap. The engine mounts take some work - after removal, you have to drill out the factory rivets to split the two halves.

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    I am also thinking mounts. The vibration could go away with the engine twisting under throttle.

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    Quote Originally Posted by pajeff02 View Post
    Transmission mount is a snap. The engine mounts take some work - after removal, you have to drill out the factory rivets to split the two halves.
    so I drove the car today and I noticed it didn't vibrate in park or neutral just in drive and a lil in reverse when stop at light with foot on brake. when I was leaving a store it got worse and sounds like its coming feom under pass seat but goes away once I put it park or give it gas

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    Junior Member jefff82's Avatar
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    so maybe a busted trans mount since its right where the vibration is coming from. seems easy to replace . what causes the trans mount to break besides age.

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    I went out and looked to see about the trans mount. I feel that the tunnel brace is where the noise is coming from and is right underneath the seat where I heard the noise. if I take the brace off will it affect anything. im still going to look at the tranny/ motor mounts. it wont hurt to get them replaced

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    You can either remove the tunnel brace, or simply space it down from the body a bit using longer bolts, some washers, or a set of oversize nuts.

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