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isolating vibration #1578872
02/14/14 11:45 AM
02/14/14 11:45 AM
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bonefish Offline OP
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in nuetral when i slowly rev my engine i get a very noticable vibe.it starts at 2,000 rpm and stops at 2100 rpm.everything else is smooth.my TC bolts came loose,first time ever in any car ive had.is there any way to isolate the prob without just changing parts?

Re: isolating vibration [Re: bonefish] #1578873
02/14/14 12:02 PM
02/14/14 12:02 PM
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Crizila Offline
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Vibrations like that ( narrow rpm band and go away on ether side ) are often exhaust system related. I'd start there.


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Re: isolating vibration [Re: Crizila] #1578874
02/14/14 02:09 PM
02/14/14 02:09 PM
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bonefish Offline OP
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Actually, now that ive got my AFR alot better i can actually feel the vibe at cruz.it pulses.i,m wondering is what im feeling is a drone or a vibe.its not horrible but you can feel it.

Re: isolating vibration [Re: bonefish] #1578875
02/14/14 02:20 PM
02/14/14 02:20 PM
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Romeo MI
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Quote:

Actually, now that ive got my AFR alot better i can actually feel the vibe at cruz.it pulses.i,m wondering is what im feeling is a drone or a vibe.its not horrible but you can feel it.




Was it super lean on A/F... might be detonation

Re: isolating vibration [Re: MR_P_BODY] #1578876
02/14/14 02:31 PM
02/14/14 02:31 PM
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bonefish Offline OP
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my AFR meter reads 14. to 14.8 at cruz if i give it a little gas it will read about 12.to 13 till it levels out and you still feel the slight vibe at the richer AFR.

Re: isolating vibration [Re: bonefish] #1578877
02/14/14 02:44 PM
02/14/14 02:44 PM
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Romeo MI
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Quote:

my AFR meter reads 14. to 14.8 at cruz if i give it a little gas it will read about 12.to 13 till it levels out and you still feel the slight vibe at the richer AFR.




You should be fine there..... lets go back to the
beginning of the build ... is the engine balanced,
what balancer, is it a stick or auto, if auto what
flex plate... give us a little info

Re: isolating vibration [Re: MR_P_BODY] #1578878
02/14/14 02:55 PM
02/14/14 02:55 PM
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bonefish Offline OP
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Quote:

Quote:

my AFR meter reads 14. to 14.8 at cruz if i give it a little gas it will read about 12.to 13 till it levels out and you still feel the slight vibe at the richer AFR.




You should be fine there..... lets go back to the
beginning of the build ... is the engine balanced,
what balancer, is it a stick or auto, if auto what
flex plate... give us a little info



yes the engine has been balanced,it has an ATI bal.its an auto,flex plate is(i think)a BM it was on another motor with no vibe.the only change i made to the short block was going fron 13-1 compr.down to 10.2,and it was all rebalenced.

Last edited by bonefish; 02/14/14 02:56 PM.
Re: isolating vibration [Re: bonefish] #1578879
02/14/14 03:04 PM
02/14/14 03:04 PM
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Romeo MI
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A ATI is a quality balancer but have you checked the
zero to TDC... is anything loose(flex plate, conv),
have you checked the flex plate for a crack... I had
one crack years ago that the buzz gave it a small vibration

Re: isolating vibration [Re: bonefish] #1578880
02/14/14 03:37 PM
02/14/14 03:37 PM
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Crizila Offline
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Quote:

Actually, now that ive got my AFR alot better i can actually feel the vibe at cruz.it pulses.i,m wondering is what im feeling is a drone or a vibe.its not horrible but you can feel it.


Try rolling in a fresh set of plugs or gapping the existing a little closer and see if that helps. Assume a Comp test / leak down test has been done and all is good inside ( no weak holes)? Drone / pulsing vibs are usually drive train related?


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Re: isolating vibration [Re: Crizila] #1578881
02/14/14 04:06 PM
02/14/14 04:06 PM
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bonefish Offline OP
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when i put the cam in i checked the bal. its dead on.asfar as cracks i didnt notice any and the plate had a nice ring to it.it does seem to go away if i cruz at 3,500 rpm or higher.

Re: isolating vibration [Re: Crizila] #1578882
02/17/14 09:22 PM
02/17/14 09:22 PM
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bonefish Offline OP
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Quote:

Vibrations like that ( narrow rpm band and go away on ether side ) are often exhaust system related. I'd start there.


well, after chasing my tail on this thing i finally broke down and loosened up my exaust hangers,GUESSWHAT,no more vibration.now to do a mod and it should be fine.sometimes its the simple stuff.THANKS.

Last edited by bonefish; 02/17/14 09:23 PM.






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