LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

knocking under car

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Old Jan 5, 2006 | 09:25 PM
  #1  
97formula808's Avatar
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knocking under car

i'm really not sure where this knocking is coming from. you can feel it hitting the floorboards. it usually happens as i'm coming off the gas. sometimes if i go to accelerate again slowly, ill get a knock. it usually happens when i'm at 50mph and i let off the gas and teh engine idles at 1.5K rpm and will knock consistently until i get back on teh gas or the off gas idle goes beneath 1.5K rpm. i recently installed prothane motor mounts, prothane tranny mount, and pacesetter headers. the headers seem to have good clearance. if i rev in neutral, no knocking happens. anyone have a clue to whats happening? its really frustrating.
Old Jan 5, 2006 | 09:28 PM
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Re: knocking under car

Is it an auto or a stick?
Old Jan 5, 2006 | 09:53 PM
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Re: knocking under car

sorry bout that A4
Old Jan 5, 2006 | 10:25 PM
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Re: knocking under car

can you tell kinda what area that the noise comes from? Engine or trans area? Is oil pressure good? I had the same type of noise happen to me twice. Took my trans out and found I had crack my flex plate. The bolt holes in the center had crackes going all the way around. It had a thumping noise like a rotating sound. I thought at first it was something with the crank. But anyway i've cracked two of them so far and both times same sound. Its easy to take out the trans to. I changed my converter with a better stall to. If its out might as well upgrade.
Old Jan 5, 2006 | 11:07 PM
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Re: knocking under car

it seems to be coming from from between teh two front seats or by the foot wells. it hitting the floorboard amplifies the sound. did anyone have this symptom? this is really irritating. i dont think its the flexpipe as it hitting under the floorboard.
Old Jan 6, 2006 | 05:56 AM
  #6  
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Re: knocking under car

Is it more of a vibration or aknocking noise?
Old Jan 6, 2006 | 08:44 PM
  #7  
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Re: knocking under car

its definately a knock
Old Jan 6, 2006 | 09:30 PM
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Re: knocking under car

Check the tranny mount
Old Jan 6, 2006 | 11:05 PM
  #9  
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Re: knocking under car

If it's not the tranny mount i'm tellin ya check the flex plate.
Old Jan 6, 2006 | 11:18 PM
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Re: knocking under car

couldnt a broken torque arm mount cause this too?
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