So I have had a nightmare of a car build over the past year. I have a 2006 G35 Coupe 6MT and had the motor rebuilt with upgraded internals and a lot of replacements, all OEM or better. I installed the HKS GT Pro Kit V2 and had it tuned by a tuner with UpRev. I've had these weird issues of super hard deceleration when letting of the pedal, like triple the amount of engine braking I should have. Its so severe that the car is undrivable at low RPMs because of how harsh it transitions from no load and deceleration to acceleration with just a little application of throttle, almost like there's excessive vacuum in the engine and its fighting the car to slow down. I definitely knew something was up but had no idea what could be causing it, and my tuner swears the tune was good since that problem only appeared a month after the car was dyno tuned with all parts and the supercharger installed.

Recently I got my hands on a collection of different android OBD apps and another UpRev interface cable (somehow lost my cable with my tuner license a few years ago). With all of the different programs, I've confirmed that my Bank 2 (driver side) consistently has about 11 degrees more exhaust valve timing than Bank 1. I would expect EVT to be close 0 at low load and rpm, and the Nissan Service Manual says it should be be between -5 to +5. Bank 1 is always in that range at idle, usually about 1 degree, and slowly increases with RPM. Bank 2 always seems to stay around at around 11.5 to 12 degrees at idle, but also increases with RPM identically to Bank 1. Reading the manual and doing research, it appears the exhaust timing is controlled by a magnetic drag damper that sits inside the VTC cover.

I had the shop that built my motor do an inspection to find the oil leak that keep plaguing me and didn't start till after the supercharger install. They found tiny leaks from the valve cover, VTC solenoid (the top mounted intake one), and a moderate one from lower corner of the VTC cover, all on Bank 2 right where the supercharger is mounted.

Is it possible that an oil leak in the VTC cover could be causing that consistent 10 degree difference? Or is it more likely to be something else, like an electrical issue? I kind of doubt the latter since the timing changes consistently with the other bank, so clearly its receiving commands and voltage from the ECU. I also confirmed talking to UpRev that the software does not allow for independent control of variable valve timing between banks, so it shouldn't be a tune issue. Furthermore, what the heck could be causing all of those gaskets to fail on that side when they were brand new, and the valve cover is brand new OEM too? I would think excessive heat from the supercharger could be a possibility, but all of those components are literally designed to have hot engine oil flowing through them already.

I'm about to spend a whole weekend removing the supercharger to address the oil leaks, but debating on buying another VTC cover or just seeing of a new gasket could fix all my issues. Both new and used VTC covers for VQ35DE RevUps are extremely overpriced for what they are.