if you are using blender there's an option here on the transform menu called backface culling that will make flipped faces transparent allowing you to easily find your wrong directioned faces
went there, done that, nothing was transparent. hmm. the flipped faces dont look flipped either, they react to lighting normally and look fine.
crazy's pickin up the ropes!!
after you find out what faces are inverted you can select them and do recalculate normals on them. or the easier way is to just select your entire model and select recalculate normals
ayyy
alright ill try that.
edit : did it. looks fine in blender, looks fine in my 3d model viewing app, looks the same in p3d
im just gonna assume its p3d