So I have successfully installed a VQ35HR head onto a VQ37VHR block and timed it. I have noticed that the passenger side bank looks normal regarding the coil packs but the driver side coil packs had a white chalky residue on them. The block that I got the heads from also had o2 sensors missing from the same driver side exhaust manifold as well.. Do you think its the bad o2 sensors that causing that side to build this white chalky residue?