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Discussion Starter #1
Ok guys i am fairly new to the forum i am a gm certifed tech. heres my problem i need to know how many more there are. in the shop i have a 06 lbz with a pulsing vibration at idle easily felt from drivers seat the intensity increases as it warms up i can also make it increase by raising the idle to the 1300-1400 rpm range. good news its not the engine as i have just replaced it per gm engineering fr the dmax plant has instructed me to. i know its not trans due to disconnected converter vibration still there. oh and the best part this was cought on pdi it only has 4 miles on it. any input i can get from owners may help me and gm find the cause of this
thank you.:confused: :confused:
 

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did you replace the entire motor ( damper, flexplate, fan clutch ect)
 

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Have you tried disconnecting the exhaust to see if the vib stays? Sounds like a ground out.
 

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maybe it is the new measaging seats that are new for 06
 

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Discussion Starter #5
yes i replaced all components gm engineering sent me an assemby line engine all cmponents included plug and play the truck has been run without exhaust converter disconnected new mounts eng and trans all #S perfect thought it might be cal issue programmed with 06 lly cal still same swapped ecm from another lbz and reprogrammed all same am scratching my head here area engineer returns for second visit tommorow but im not conviced he has any idea.
 

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Discussion Starter #6
its a 6-12hz vibe at 680 and 1350 rpm ranging from .10 to .75 on the g meter
(eva 2)
 

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I have noticed it on my truck. Never really gave it much thought. It is a pretty rythmic vibration, though. I have noticed the same vibration in a large International with a DT570 we have at work.
 

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Discussion Starter #8
replaced ntire engine (assembly line eng direct from dmax plant) plug n play. ran with no belt converter and exhaust disconnected new monts eng and trans no change in vibration 6-12hz 680 and 1350 rpm .10-.75g's w/eva2. tried diff fuel checked balancer pin new and old eng. tried lly program no change tried new ecm no change theyv'e got me runnin in circlesand the area eng. will be back tommorow for ound two. at this point im into it 55 hours straight plus 9.5 hours or eng swap its not a sold unit thank god but im running out of patiece.
:help: :help: :help: :help: :help: any input is great the area eng said he went to the roseville dealer and checked all of their stock units and found 4 that di the same w/ only 1 at a comparable strength to the one ive got. its extremely noticeable immediatly after start up itll shake the mirrors.
 

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Discussion Starter #9
I have noticed it on my truck. Never really gave it much thought. It is a pretty rythmic vibration, though. I have noticed the same vibration in a large International with a DT570 we have at work.[

when it warmed up does it get worse ? if you raise the rpm at a stop in ark to around 1300-1400 rmp do you feel it again? scale of 1-10 1 very minor 10 -moves your mirrors?? thank you for your reply whats you build date (on the door sticker) ? mileage?
 

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It doesn't shake the mirrors at all. I haven't driven it for a couple of days and, to be honest, I really don't pay much attention to it anyways, so I can't say if it is worse when it is warm or cold. I can say it isn't bad enough to shake the mirrors or rattle anything inside the truck. I just kind of feel a little vibration in the seat is all. It was built 08/05 and the current mileage is a hair over 7k. I'll drive it tomorrow and get back with you on the other stuff I couldn't answer.
 

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I have an 05 LLY and it has a vibration at idle in park. It comes and goes rhythmically. Almost liked a gasser with a big cam. I'm pretty sure mine is from the engine though.
 

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Discussion Starter #12
that sounds exactly like mine i still swear its an engine problem but i would have to be two in a row thanks josh much appreciated
 

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tech :
I would bolt the trans up to the new one and run it , if you havent allready .
Electronic controled engines require a large rotating mass ,(flywheel torque converter)so the engine does not hunt maintaining a specific rpm .
Try it you may like it.

:)
 

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Discussion Starter #14
have done that right now its all together and has been driven newmotor is exactly the same.
 

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shoot in the dark:

EMI from another electrical componant not on the engine as you would have replaced those.

also i had an old mustang with the fluid mounts that would vibrate like heck when i blew one wasn't easy to see but you sure could feel it
 

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did the new motor come with a new injection pump and injectors? Could it be the fuel pressure regulator? can u ramp fule to 160Mpa's? just a thought
 

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Discussion Starter #17
yes it came with all pump injectors and all injectors are programmed correctly
it will ramp to 180 balance rates good.
 

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O yeah i forgot you have to program for each injector! thats just stupid. but realy the only thing it could be is programing or. there is a wire pinched somwhere giving the ECM a wrong reading. Could the FICM have gotten wet when it was PDI'ed or did that come new aswell. Also could someone have put gas in it when PDI'ed. iv seen that happen. stupid sales men
 

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Discussion Starter #19
pooch you should really go look at a new o6 lbz no more ficm and the ecm is no longer delphi it has a bosch pcm and they program each injector to better meter the fuel to make cleaner and more power. and ive drained and refilled tamk w/new fuel no chance of gas in it it had only three gallons in it from the factory. but i tried new anyway in case of poor quality but no such luck.
 

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Well you guys have covered alot of what it could be. I say cracked frame missing frame rivet bad frame cross Allowing a frame harmonic.??
 
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