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2009 Silverado Hybrid bucking violently

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My brother and I picked up a 2009 Silverado Hybrid with what was supposed to be a bad motor.

Put a rebuilt motor in along with a new AGM battery and the truck bucks violently after starting the engine and so now I'm trying to figure out what is going on. Going to hook the Tech II up to it again (unfortunately the Tech II card is a 2010 so it's not the latest).

VVT and AFM were deleted using the parts, but they are not programmed out of ecm yet as I was told that as long as I used all the hard parts for deleting those, the computer wouldn't be able to do anything to cam degree, or cause the engine to go into 4-cyl mode in any way (not even fueling).


New engine details:

 I picked up an identical 'core' that wasn't able to start from a local salvage yard (lucky to find a LFA core within 50 miles) and went to town collecting parts to rebuild it, but with some changes, utilizing factory parts and an aftermarket Melling 10295 oil pump.

Parts used for the rebuild (all new or rebuilt):

GM LS3 head gaskets (verified they are the same thickness as LFA gaskets)

GM/FelPro Head bolts

Comp Cams Trunion kit installed in rocker arms (verified the trunion bearings weren't pushed in too tight -seen it where some were put in too tight and the rocker wouldn't pivot, wiping out pushrods, lifters, cam and breaking the tips off the rocker arms themselves)

GM LS7 lifters 

GM LS7 lifter trays

GM LY6 valley cover

GM LS9 camshaft

ARP cam bolts

LS9 4x cam sprocket

rebuilt stock 243 heads

LS9 valve springs

LS2 timing chain

LS3 timing cover (no VVT)

LS2 timing chain dampener

Durabond coated cam bearings (original front cam bearing had a little scoring so I got the new bearings for peace of mind/cheap insurance).

Clevite 77 main and rod bearings (stock sizes as there was no crank/rod damage)

Piston-to-valve clearance was measured and stock pushrods from another engine were used as they were a perfect fit)

New oil pressure barbell

New timing/rear main cover/valve cover/valley cover gaskets

Block was cleaned and checked/honed prior to reassembly

Crank and cam were 'timed' prior to timing set being installed


Is there anything outside of the gas engine (aka in the hybrid system) that could be causing the truck to run so violently? Truck has 142,xxx miles.

 Thanks in advance for any help.

Edited by 007inblack

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