Bad milage, CEL Code P0171

[kd7skx]

Hi all,

So I am trying several nissan fourms to see if I can get any ideas on my trucks problem. I am getting 15 mpg and I know I should be getting in the 20's.

It is a 97 2wd 5speed 4cyl pickup.

So far from suggestions on other sites and googleing I have done this,

Seafoamed oil, put in vacuum lines, and fuel.
New sparks, wires, cap, rotor, oil, air filter, MAF and fuel filter.
I have checked with propane, several times, for vacuum leaks and have not found any.

I am thinking O2 sensor or maybe the temp sensor in the air filter housing now.

Any help or idea would be appreciated. Thanks

[Saudade]

http://www.obd-codes.com/p0171

[kd7skx]

Thanks for the link, already know what the code is and what the definition is. Been trying to track down the culprit.

[346ci]

What is your fuel pressure? Key on engine off should be 43 psi(to prime pump). At Idle should be 34psi.