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Discussion Starter #1
my 550, has a 6.0 4.88 gears, sct livewire, custom tow tune and 4 inch turbo back. i noticed sometimes when i put it under a hard pull when the converter locks up and boost goes over 25-28 sometimes it will pulse , it has done it twice. both times hard enough it was like i was pumping the pedal. if i let off and let it dump boost pressure and then get back into it , it will quit. any ideas what that is? and the boost psi is not fluctuating , it just stays at 28.89 on the livewire. never goes any higher. and engine temp was 198 the first time and 206 the second time if it means anything.
 

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Kinda sounds like what mine does... which I'm pretty sure is the torque converter clutch.... but if it only does it with a load... then maybe it's related to the hitch or something... I'm just throwing the possible TCC out there...

Are you talking about a LOAD or a load on the engine? Because mine does it anytime I'm rolling on it hard.... it locks, and then kinda pulses...
 

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Discussion Starter #3
when it has done it , it has been under heavy engine load, last night i was in the neighborhood of 25-30k lbs gross
 

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Village Idiot
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Is it only in the lower gears? Sometimes axle wrap with a heavy load will change the pinion angle enough to cause a driveline vibration that feels like that. I wouldn't think it would be as prominent on a 550 but my 350 will do it with a heavy bumper pull style trailer.
 

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DD Assisted
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My buddies truck was doing that same thing. Ended up being a something to do with the egr system. Some kind of sensor if I remember right?:confused: He got it replaced and it runs good now. Good Luck.
 

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Discussion Starter #8
no the way it feels is like motor not tranny, and when i first take off i feel the axle wrap up a little but i always take off easy so it doesen't because i don't like the feeling. it may have something to do with the egr system, as it only happens under high boost, the only thing i didn't know was my EGT at that moment.
 

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no the way it feels is like motor not tranny, and when i first take off i feel the axle wrap up a little but i always take off easy so it doesen't because i don't like the feeling. it may have something to do with the egr system, as it only happens under high boost, the only thing i didn't know was my EGT at that moment.
I had issues goin down the 1/4 mile.

At the top end of the track past the 1000 foot mark the truck would buck.

stock with the issue I ran 18.2 after I unplugged the egr valve and I did a 17.3 non boosted run. :D
 

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AllYourBaseAreBelongToUs
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How accurate is that Livewire? I've heard that as one of the downsides of digital guages, they won't react quick enough to see minor fluctuations such as turbo surge.
 

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Discussion Starter #12
well the gauge on the dash was not bouncing or moving at all. and the livewire seems to read very quickly. and the boost was not jumping around. but on the livewire it NEVER went over 28.89 psi. saber, i do believe the egr system is turned off as i am running one of erics tow tunes.
 
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