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The differential limit between the cylinders, regarding compression is 14 psi. Anything higher and it could be indicators of piston rings wearing out. Also, some 2011-2013 QX56s were plagued with the timing chain/oil jet issues that Infiniti did recall but unfortunately expired.
 
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To ensure the intake valves are closed, you have to start off with manually turning the crankshaft pulley to TDC. Once you do that, insert a long screwdriver or dowel into cylinder 1 and note the height of it. Insert it to the other cylinders, compare the height and and you'll see differences. An old school method is to leave the screwdriver or dowel in place and while turning the crankshaft pulley, you'll see the screwdriver or dowel rise up (closed) or drop down (open).

To thoroughly clean the intake manifold, spray brake cleaner, throttle body cleaner, etc into the intake ports on top of the intake manifold where the PCV hoses connect to. Also, where the MAP sensor plugs into the rear of the intake manifold. You'll also notice next to the MAP sensor location is another port that is plugged up. Remove that and spray away. There's going to be a lot more residual oil that will drain out from the intake manifold.
 

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@AYCHE, sorry for the confusion about turning the crankshaft. I completely forgot these VK56VD motors are VVEL operated so the intake valves are closed regardless. I just remembered when the first time I did this DIY years ago, I questioned it too and learned afterwards on why the intake AND exhaust valves stay closed at TDC.
 
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Just make sure the crankset pulley is at TDC.

I doubt you damaged anything with the VVEL disconnected. If anything, when you plug everything back in, it'll probably show a DTC for the VVEL since it was disconnected when you had the truck switched on.

Btw, this was a thread I created almost 2-1/2 years ago when I did this DIY GDI cleaning and diagnosing a stubborn P0171/P0300.

 
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