Car has trouble starting sometimes and I have also just recently replaced the spark plugs. The problem is when I try to tune the apexi vafc, adjustments made to it does not affect the actual a/f ratio on the dyno as it should. On a side note the 2nd o2 sensor is unplugged and the ecu occassionally throws a code 63. Does the problem lie with the ecu or vafc? Or is it a fuel problem? Sensor? The dyno indicates that the car is running very lean.

 

vafc can only do so much...

not knowing what your actual setup is...
i guess that you will probably need a fuel pressure regulator and larger injectors

 

aem cold air intake, spoon n1 muffler and a hollow cat plus a fuel pressure regulator but i am unsure of its settings

 

get a gauge for the fpr