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Thunking when idling at stop

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Old Jan 16, 2012 | 02:15 PM
  #1  
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Default Thunking when idling at stop

So I've noticed lately that when my car is fully warmed up and I'm stopped at a light, there is a slight "thumping" noise..

Now, I haven't quite figured out if its the engine or exhaust, (it snowed today so I figured I'd ask and I'll check for sure tomorrow).

The hard part about checking it is --- it ONLY happens when in Drive (this is an Automatic) and I'm stopped.

So putting it into park or neutral and the noise disappears.
So I'm going to have my girl hold it in park while I check.

Any ideas?

The car is 112k miles now, the 1 owner before had the car sit for a long time.
I'm gonna be swapping the spark plugs soon too.
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Old Jan 16, 2012 | 02:20 PM
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Pretty sure it's trans related, I have a similar problem while slowing down or idling through a parking lot, etc.
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Old Jan 17, 2012 | 08:32 PM
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mines exactly like that. its my ypipe hitting the floor.
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Old Jan 17, 2012 | 08:35 PM
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Yes it is probably the exhaust hitting the floor. A exhaust mount could be worn out or needs a new one. It is a easy fix.

Also a vid of the noise would help us figure out what it could be. A exhaust rattle is like thumping noise that is rapid and some times does away while driving but comes back at a stop.
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Old Jan 18, 2012 | 01:22 PM
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Exhaust rattles tend to go away when under load since there is less shaking... Assuming your mounts aren't shot. Does the rattle occur while still in drive, but waiting at a stoplight? I have had resulting from my flexplate bolts being loose. Have you removed the tranny recently for any reason?
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Old Jan 18, 2012 | 01:24 PM
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I vote for the tranny mount. Mine thuds when I put the car in first at stop signs. The autos and sticks share the same mount so it's not just because it's a stick.
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Old Jan 18, 2012 | 04:31 PM
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I'll be checking this weekend for sure.
I have not replaced the Transmission or Engine.

I got the car from the original owner and it had 110k miles w/no mods on it at all.

I've recently replaced all the fluids and what not so I don't think that could harm it.

LOL I say we take a vote! I don't think its the exhaust hitting the floor tho :/
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Old Jan 21, 2012 | 10:57 PM
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when in drive and its making the noise have you noticed a slight rpm drop when it hits and the lights dim. mine drops rpm about 100 and lights dim but doesnt do it every time the ypipe hits just occasionally.
would the ypipe hitting cause this or is it something more serious??
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Old Jan 22, 2012 | 12:38 AM
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Hijack: where is the tranny mount at? Mine's been doing that for a year and I ahven't beena ble to figure it out. Might be worth checking out.
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Old Jan 22, 2012 | 12:51 PM
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I Vote MM.
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