my vehicle just started smoking!

Question

my f-150 4.6 liter has 103.000 miles and hasn't ever over heated,it just pulled out a p0171 code and it started smoking yesterday and I cant figure out my problem!i checked oil and water and no sludge in either of them and have good compression.im hoping that its not a valve or oil rings!theres no knock or anything that's obvious.can someone give me an idea or if anyone has had this problem give me some advice?i have twenty five years experience in automotive but cant figure what it could be.it runs very good no misfires or knocks and it has never over heated!thanks hope to get an answer.

Answer 1

check the PCV hoses, they have a elbow on it by the plenum and the firewall

Answer 2

i replaced the pcv and complete line and checked for leaks .

Answer 3

my problem now is the smoke thats comiing out of tail pipe.it doesnt look good and what really gets me is im hoping its not a major problem!