Horrible Vibration and No Acceleration

[Core2012]

Hey guys,

I have a 2003 6.0 i have been fighting a problem with for 3 months now and cant figure it out. Right after shifting into 2nd threw 5th my truck vibrates horribly only at low rpms after getting back up to about 2000-2200 the shaking mellows out until hitting overdrive then it shakes horribly again, I've replaced u-joints, just replaced my rear end i shreadded my spider gears. I have not had it balanced yet i'm thinking that may be it? Also in 5th and overdrive if I try to accelerate the shaking gets a lot worse and turns into like a hop. I have to let it shift down into third before i can accelerate again. Any ideas?

[twoicebergs]

Since you said it was more RPM specific, my thoughts are towards a bearing in the transmission, torque converter, transfer case or the friction plates. However, after 3 months, I would have expected it to have shown you the money, so to speak.

4x4 or 2wd?

You still need to confirm:

Driveshaft out of balance or bent.
Driveline angle changed recently, new lift kit.
U-joints, yeah I know you said you changed them.
Pinion shaft or bearing.
Wheel/axle bearings.

[Core2012]

I will say too it dose not shake near as bad stock, when its tuned is when the shaking really gets bad. When I blew my rear end out just before Christmas I rebuilt the rear end with Detroit True Traxs, I did not do anything with the pinion. Someone before welded a washer on the longest drive shaft to hold the u-joint in. I had a new end welded on at Lima clutch and joint thinking that would fix it but it hasn't I did not have them balance my drive shaft I'm thinking I should have. It is 4x4 but It hasn't had a front drive shaft since last August. The truck has had a 6.5 inch lift with 37s for a few years now. With the new rear end, u-joints, and end on the drive shaft it hasn't seemed to get better. When I run a 150 hp tune and used its just a small vibration but anything over 150 will really shake the truck. I also but a new carrier bearing on the drive shaft.


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[southend]

Do you have a monitor? Does it idle well?

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[Core2012]

Yes sct livewire ts. Yes it seems to idle okay.


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[southend]

Originally Posted by Core2012

Yes sct livewire ts. Yes it seems to idle okay.


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Not sure how the sct is on pulling codes, it sounds like bad injector(s). Just a thought.

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[twoicebergs]

It does not shake near as bad stock, but when it's tuned, the shaking really gets bad.

That kind of makes me think you have an injector or 2 misfiring under load at higher rpm. The FICM could be part of the problem, intermittent voltage reductions from the unit or the alternator. You can probably check the voltage when it happens with your monitor, but you would need a diagnostic tool like AE to catch the injectors for contribution and balance.

Other known causes of bucking under load with lower rpm are the turbo could be sticking, vanes or actuator. As well, the EGR could be doing the same.

[Karls03]

What's your carrier bearing look like? Pushing it straight down when lifting a truck is the quickest way to destroy one. The carrier bearing needs to be rotated to maintain a straight line through it when lowering it for a lift. Pushing it straight down puts a bind on the input side.

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