Nissan Repair: 04 Sentra Cold start problem, fuel pressure gauge, fuel pressure regulator

Question
I've recently checked all sensors,mas,tb-position, crank and cam position. O2 sensor and ectemp.All were within spec. -4 degrees car won't start.Black smoke is visible (over fueled). Plug in block heater and car starts with severe hunting. When engine reaches full operating temperature bucking stops and car runs perfect and is drivable as the day it was purchased.

Answer
Johnny,

If the car is over rich in cold start mode then there is a problem with leaky injectors or a blown fuel pressure regulator.  Get a fuel pressure gauge and hook it up to the fuel rail.  You will need an adapter since they deleted the schrader valve that you used to be able to screw the gauge into.  Check the pressure against specified range.  Get a Haynes Manual or a factory service manual.  The factory one can be obtained by download at nissantechinfo.com  The cost is $20 bucks for an hour worth of download time.  You have to download them in PDF.